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Please use this Discussion Thread for the situation in Japan with respect to the Miyagiken-Oki earthquake (9.0 magnitude) and associated 10m tsunami, and its impact on the local nuclear reactors. Here is a précis of the situation as I understand it:
1. There is no credible risk of a serious accident. All reactors responded by insertion of control rods to shut down their nuclear reactions. Thus, power levels in all cases dropped quickly to about 5% of maximum output, and the nuclear chain reaction ceased (i.e., all units are subcritical).
Note: I judge the situation would currently be rated INES Level 4: Accident with local consequences on the international nuclear event scale. Update: This level has been confirmed by WNN (5:50 GMT).
2. The concern is providing emergency cooling water to the reactor cores to remove decay heat from the fuel rods. This residual heat comes from the fission products, and will be persistent, but diminishes rapidly over time (i.e., most decay heat occurs over minutes and hours, with cold shutdown within a few days).
3. At one plant, the 40-year old Fukushima Daiichi (unit #1 opened in 1971), the backup diesel generators supply power to the core cooling system failed (apparently due to damage from the tsunami). This allowed pressure to build up in at least one of the reactors cores to about 50% higher than normal (unit 1), and requires venting of very mildly radioactive steam (contains trace levels of tritium). Some discussion here.
4. The nuclear reactor containments were undamaged by the tsunami or earthquake — these structures are sealed from flooding damage and are seismically isolated.
5. New generators and batteries have been transported to the Daiichi site in to provide power to the pumps. The emergency core cooling systems (ECCS) have been invoked, which follows the principle of defense in depth (however, see point #8, below, and TEPCO updates).
6. There are reports of partial exposure of the fuel at Daiichi unit #1, following coolant evaporation that, for a short time, exceeded inputs from the secondary cooling system. Such exposure can lead to some melting of the metal cladding (the ‘wrapping’ of the fuel rods), or the uranium rods themselves if the exposure is prolonged. This is what is technically referred to as a ‘meltdown’. I am still not clear if this exposure of the fuel assemblies actually happened (some evidence here), nor if any fuel underwent melt (due to decay heat, not a critical nuclear reaction).
7. The plant closest to the earthquake epicentre, Onagawa, stood up remarkably well, although there was a fire in a turbine building on site but not associated with the reactor operations, and therefore was not involved with any radioactive systems.
8. There has been an explosion at Fukushima Daiichi at 16:30 JST (7:30 GMT) on March 12. Note: There is no critical nuclear reaction occurring in any of these reactors, and it CANNOT reinitiate as all neutron-absorbing control rods are grounded. As such, any at a plant site fire would be chemical (e.g., hydrogen) or steam pressure during venting (see point #3).
Quote from WNN on the explosion:
Television cameras trained on the plant captured a dramatic explosion surrounding Fukushima Daiichi 1 at around 6pm. Amid a visible pressure release and a cloud of dust it was not possible to immediately know the extent of any damage. Later television shots showed a naked steel frame remaining at the top of the reactor building. The external building structure does not act as the containment, which is an airtight engineered boundary within.
Chief cabinet secretary Yukio Edano appeared on television to clarify that the explosion had damaged the walls and roof of the reactor building but had not compromised the containment.
Monitoring of Fukushima Daiichi 1 had previously shown an increase in radiation levels detected near to the unit emerging via routes such as the exhaust stack and the discharge canal. These included caesium-137 and iodine-131, Nisa said, noting that levels began to decrease after some time.
Nevertheless the amount of radiation detected at the site boundary reached 500 microSieverts per hour – exceeding a regulatory limit and triggering another set of emergency precautions. It also meant the incident has been rated at Level 4 on the International Nuclear Event Scale (INES) – an ‘accident with local consequences’.
Note: The seawater might be used for spraying within the containment, for additional cooling, rather than injection into the reactor core. That is what comes of too much uncertainty and too little hard information.
Japan Chief Cabinet Secretary Yukio Edano, via Reuters:
We’ve confirmed that the reactor container was not damaged. The explosion didn’t occur inside the reactor container. As such there was no large amount of radiation leakage outside…
Edano said due to the falling level of cooling water, hydrogen was generated and that leaked to the space between the building and the container and the explosion happened when the hydrogen mixed with oxygen there.
(I will edit the above section and provide further updates below, as more information comes to hand)
Some useful links for further information:
Battle to stabilise earthquake reactors (World Nuclear News)
Factbox – Experts comment on explosion at Japan nuclear plant (some excellent and informative quotes)
ANS Nuclear Cafe updates (useful news feed)
How to Cool a Nuclear Reactor (Scientific American interview with Scott Burnell from the NRC)
Nuclear Power Plants and Earthquakes (World Nuclear Association fact sheet)
Tokyo Electric Power Company updates here and here (the plant operators)
Capacity Factor: Some links on the Fukushima Daiichi #1 crisis (with updates)
This is a critical time for science, engineering and facts to trump hype, fear, uncertainty and doubt.
——————————
Updates Below
International Atomic Energy Agency: Japan nuclear plants nearest earthquake safely shut down
TEPCO updates for Fukushima Daiichi (Plant #1) and Daini (Plant #2): 8 am, 13 March
[Nuclear Power Station]
Fukushima Daiichi Nuclear Power Station:Units 1 to 3: shutdown due to earthquake
Units 4 to 6: outage due to regular inspection
* The national government has instructed evacuation for those local residents within 20km radius of the site periphery.
* The value of radioactive material (iodine, etc) is increasing according to the monitoring car at the site (outside of the site). One of the monitoring posts is also indicating higher than normal level.
* Since the amount of radiation at the boundary of the site exceeds the limits, we decide at 4:17PM, Mar 12 and we have reported and/or noticed the government agencies concerned to apply the clause 1 of the Article 15 of the Radiation Disaster Measure at 5PM, Mar 12.
* In addition, a vertical earthquake hit the site and big explosion has happened near the Unit 1 and smoke breaks out around 3:36PM, Mar 12th.
* We started injection of sea water into the reactor core of Unit 1 at 8:20PM, Mar 12 and then boric acid subsequently.
* High Pressure Coolant Injection System of Unit 3 automatically stopped. We endeavored to restart the Reactor Core Isolation Cooling System but failed. Also, we could not confirm the water inflow of Emergency Core Cooling System. As such, we decided at 5.10AM, Mar 12, and we reported and/or noticed the government agencies concerned to apply the clause 1 of the Article 15 of the Radiation Disaster Measure at 5:58AM, Mar 13.
In order to fully secure safety, we operated the vent valve to reduce the pressure of the reactor containment vessels (partial release of air containing radioactive materials) and completed the procedure at 8:41AM, Mar 13,
* We continue endeavoring to secure the safety that all we can do and monitoring the periphery.
Fukushima Daini Nuclear Power Station:
Units 1 to 4: shutdown due to earthquake
* The national government has instructed evacuation for those local residents within 10km radius of the periphery.
* At present, we have decided to prepare implementing measures to reduce the pressure of the reactor containment vessel (partial discharge of air containing radioactive materials) in order to fully secure safety. These measures are considered to be implemented in Units 1, 2 and 3 and accordingly, we have reported and/or noticed the government agencies concerned.
* Unit 3 has been stopped and being “nuclear reactor cooling hot stop” at 12:15PM.
* The operator trapped in the crane operating console of the exhaust stack was transferred to the ground at 5:13PM and confirmed the death at 5:17PM.
Kashiwazaki Kariwa Nuclear Power Station:
Units 1, 5, 6, 7: normal operation
Units 2 to 4: outage due to regular inspection
From Margaret Harding:
Heat from the nuclear fuel rods must be removed by water in a cooling system, but that requires power to run the pumps, align the valves in the pipes and run the instruments. The plant requires a continuous supply of electricity even after the reactor stops generating power.
With the steam-driven pump in operation, pressure valves on the reactor vessel would open automatically as pressure rose too high, or could be opened by operators. “It’s not like they have a breach; there’s no broken pipe venting steam,” said Margaret E. Harding, a nuclear safety consultant who managed a team at General Electric, the reactors’ designer, that analyzed pressure buildup in reactor containments.
“You’re getting pops of release valves for minutes, not hours, that take pressure back down”
Japanese authorities have informed the IAEA’s Incident and Emergency Centre (IEC) that today’s earthquake and tsunami have cut the supply of off-site power to the Fukushima Daiichi nuclear power plant. In addition, diesel generators intended to provide back-up electricity to the plant’s cooling system were disabled by tsunami flooding, and efforts to restore the diesel generators are continuing.
At Fukushima Daiichi, officials have declared a nuclear emergency situation, and at the nearby Fukushima Daini nuclear power plant, officials have declared a heightened alert condition.
Japanese authorities say there has so far been no release of radiation from any of the nuclear power plants affected by today’s earthquake and aftershocks.
Tsunamis and nuclear power plants:
Large undersea earthquakes often cause tsunamis – pressure waves which travel very rapidly across oceans and become massive waves over ten metres high when they reach shallow water, then washing well inland. The December 2004 tsunamis following a magnitude 9 earthquake in Indonesia reached the west coast of India and affected the Kalpakkam nuclear power plant near Madras/Chennai. When very abnormal water levels were detected in the cooling water intake, the plant shut down automatically. It was restarted six days later.
Even for a nuclear plant situated very close to sea level, the robust sealed containment structure around the reactor itself would prevent any damage to the nuclear part from a tsunami, though other parts of the plant might be damaged. No radiological hazard would be likely.
World Nuclear News updates (updated 11:44 pm GMT):
Attention is focused on the Fukushima Daiichi and Daini nuclear power plants as Japan struggles to cope in the aftermath of its worst earthquake in recorded history. An explosion on site did not damage containment. Sea water injection continues after a tsunami warning.
Three of Fukushima Daiichi’s six reactors were in operation when yesterday’s quake hit, at which point they shut down automatically and commenced removal of residual heat with the help of emergency diesel generators. These suddenly stopped about an hour later, and this has been put down to tsunami flooding by the International Atomic Energy Agency (IAEA).
The loss of the diesels led the plant owners Tokyo Electric Power Company (Tepco) to immediately notify the government of a technical emergency situation, which allows officials to take additional precautionary measures.
For many hours the primary focus of work at the site was to connect enough portable power modules to fully replace the diesels and enable the full operation of cooling systems.
Pressure and releases
Without enough power for cooling systems, decay heat from the reactor cores of units 1, 2 and 3 has gradually reduced coolant water levels through evaporation. The consequent increase in pressure in the coolant circuit can be managed via pressure release valves. However, this leads to an increase in pressure within the reactor building containment. Tepco has said that the pressure within the containment of Fukushima Daiichi 1 has reached around 840 kPa, compared to reference levels of 400 kPa.
The company has decided to manage this “for those units that cannot confirm certain levels of water injection” by means of a controlled release of air and water vapour to the atmosphere. Because this water has been through the reactor core, this would inevitably mean a certain release of radiation. The IAEA said this would be filtered to retain radiation within the containment. Tepco has confirmed it was in the process of relieving pressure at unit 1 while preparing to do the same for units 2 and 3.
Explosion
Television cameras trained on the plant captured a dramatic explosion surrounding unit 1 at around 6pm. Amid a visible pressure release and a cloud of dust it was not possible to immediately know the extent of any damage. Later television shots showed a naked steel frame remaining at the top of the reactor building. The external building structure does not act as the containment, which is an airtight engineered boundary within.
Chief cabinet secretary Yukio Edano appeared on television to clarify that the explosion had damaged the walls and roof of the reactor building but had not compromised the containment.
Monitoring of Fukushima Daiichi 1 had previously shown an increase in radiation levels detected emerging from the plant via routes such as the exhaust stack and the discharge canal. Tepco have said that the amount of radioactive material such as iodine it is detecting have been increasing. The amount of radiation at the site boundary now exceeds a regulatory limit triggering another set of emergency precautions. It also meant the incident has been rated at Level 4 on the International Nuclear Event Scale (INES) – an ‘accident with local consequences’.
To protect the public from potential health effects of radioactive isotopes of iodine that could potentially be released, authorities are preparing to distribute tablets of non-radioactive potassium-iodide. This is quickly taken up by the body and its presence prevents the take-up of iodine should people be exposed to it.
Over the last several hours evacuation orders for local residents have been incrementally increased and now cover people living within 20 kilometres of the power plant.
Seawater injection
The injection of seawater into the building started at 8.20pm and this is planned to be followed by addition of boric acid, which is used to inhibit nuclear reactions. Tepco had to put the operation on hold for a time when another tsunami was predicted, but work recommenced after the all-clear.
Raised temperatures
Meanwhile at adjacent Fukushima Daini, where four reactors have been shut down safely since the earthquake hit, Tepco has notified government of another emergency status.
Unit 1′s reactor core isolation cooling system had been operating normally, and this was later supplemented by a separate make-up water condensate system. However, the latter was lost at 5.32am local time when its suppression chamber reached 100ºC. This led Tepco to notify government of another technical emergency situation.
Tepco has announced it has decided to prepare for controlled releases to ease pressure in the containments of all four units at Fukushima Daini.
A three kilometre evacuation is in progress, with residents in a zone out to ten kilometres given notice of potential expansion.
Workers
A seriously injured worker was trapped within Fukushima Daiichi unit 1 in the crane operating console of the exhaust stack and is now confirmed to have died. Four workers were injured by the explosion at the same reactor and have been taken to hospital. A contractor was found unconscious and taken to hospital.
Two workers of a ‘cooperative firm’ were injured, said Tepco; one with a broken bone.
At Fukushima Daiini unit 3 one worker received a radiation dose of 106 mSv. This is comparable to levels deemed acceptable in emergency situations by some national nuclear safety regulators.
The whereabout of two Tepco workers remains unknown.
There are a number of comments on the ‘An informed public is key to nuclear acceptance’ thread which probably should be transfered here.
(Ed: Unfortunately I do not have the ability to transfer comments across threads, people will have to repost manually)
I left a couple of questions on the appropriately named thread ‘An informed public is key to nuclear acceptance’ , and was asked to repost them here.
(and these are serious questions, so please don’t laugh them off):
1. I noticed that they “lost” the diesel backup units about the same time the tsunami hit the plant locations. Is it possible the debris from the tsunami jammed the cooling pump filters and intakes? What good would the backup electric system be, if the cooling water supply is blocked? It seems that they should have an alternative emergency cooling system in place.
2. These nuclear accidents makes nuclear plants look extremely fallible.
If one of these reactors melt down, what is the estimate for the eventual death toll, both from initial overexposure and eventually due to higher death rates due to higher radioactive levels in air, soils, and water? I would guess nuclear proponents would have these estimates at their fingertips, perhaps as a function of the amount of radioactive material released. Can one of these reactors release as much radioactive material as Chernobyl?
3. Are these reactors finished? Do you think they will run again?
4. Do the owners carry insurance to cover the financial costs associated with a failure? If the Gulf Coast oil spill caused over $50 B in damages, what is the likely financial damages if one of the reactors melts down? Roughly the same cost?
I will look for your answers to these questions.
Paul, thanks, at this stage here are my responses:
1. The generators went out after a hour or so, so I doubt they were flooded. But I don’t know the full situation.
2. No, quite the opposite. They have just performed robustly in the face of the worst earthquake ever to strike the Japanese islands.
The risk of meltdown is extremely small, and the death toll from any such accident, even if it occurred, will be zero. There will be no breach of containment and no release of radioactivity beyond, at the very most, some venting of mildly radioactive steam to relieve pressure. Those spreading FUD at the moment will be the ones left with egg on their faces.
I am happy to be quoted forever after on the above if I am wrong… but I won’t be.
3. The only reactor that has a small probability of being ‘finished’ is FD unit 1. And I doubt that, but it may be offline for a year or more.
4 Yes, they are insured. No, the costs won’t be $50 billion, more like <<$1 billion depending on what needs to be repaired, and this will all be on-site work.
There are also a few related comments on Open Thread 9, but there seems little point in copying those, or even linking, on this thread.
I have a couple of questions for people on this thread (and these are serious questions, so please don’t laugh them off):
1. I noticed that they “lost” the diesel backup units about the same time the tsunami hit the plant locations. Is it possible the debris from the tsunami jammed the cooling pump filters and intakes? What good would the backup electric system be, if the cooling water supply is blocked? It seems that they should have an alternative emergency cooling system in place.
I believe the main function of the diesel generators would be to keep the coolant water within the reactor itself circulating. Nor do I know of any mention of debris blocking the inlets for the secondary coolant flow. Sounds like you’re making stuff up.
2. These nuclear accidents makes nuclear plants look extremely fallible.
No one seems to have died yet. Apparently over a hundred people died in the oil refinery blaze in Tokyo when the earthquake struck. There also seem to be rather a lot of natgas fires burning away. This was one of the largest earthquakes in history, and most of the nuclear facilities are fine. The way they’ve performed is a tribute to the design work which has gone into them. A massive earthquake of this sort is just about the worst natural disaster you could throw at a fixed structure, and the Japanese nuclear fleet has come through it with remarkably few problems. I don’t see how that translates into ‘extremely fallible’.
If one of these reactors melt down, what is the estimate for the eventual death toll, both from initial overexposure and eventually due to higher death rates due to higher radioactive levels in air, soils, and water? I would guess nuclear proponents would have these estimates at their fingertips, perhaps as a function of the amount of radioactive material released.
Pretty much zero. As in the case of the meltdown at Three Mile Island, a meltdown would be most unlikely to result in the release of any significant quantity of radiation.
Can one of these reactors release as much radioactive material as Chernobyl?
Not by accident.
3. Are these reactors finished? Do you think they will run again?
The reactors are most likely OK, although I understand there is extensive damage to some parts of the rest of the plant. It will take time to repair it all.
4. Do the owners carry insurance to cover the financial costs associated with a failure? If the Gulf Coast oil spill caused over $50 B in damages, what is the likely financial damages if one of the reactors melts down? Roughly the same cost?
I’m not sure what the insurance arrangement for NPPs is in Japan, but any damages are likely to be limited to those of the plant itself. There shouldn’t be any external damage to be claimed on.
barry: nice job here.
I did not know that they had not invoked the ECCS.
There’s something I don’t understand. Why were they not invoked? why ship in new portable electricity sources? can eccs work without offsite electricity or diesel generator backup?
GM, the situation is not serious enough to warrant release of the ECCS. By bringing in the portable generators, they can supplement the power to the secondary system pumps and avoid a lot of later complications in the post-event cleanup/maintenance. Note that boiling water reactors like this can maintain some pump action without electricity, by using steam from the residual reactor heat to turn a turbine. Quite a neat system actually.
The US news outlets are having a field-day trying to out do each other in hyperbole over these reactors. The two worse so far has been physicist Michio Kaku [ad hom deleted] saying that these reactors were a “Chernobyl waiting to happen” and that they where on the verge of going into a “China Syndrome meltdown,” at any moment, and a CNN reporter talking about the situation at Fukushima Daini Nuclear Power Station, against a backdrop of the burning Cosmo oil refinery in Ichihara city, near Tokyo.
These are such obvious cases of bias, that I am near apoplexy.
@Barry
“Press Release (Mar 12,2011)
Plant Status of Fukushima Daini Nuclear Power Station (as of 5AM March 12th )”
I found that a few minutes ago and fed it into MY home, aus.politics. As one would assume, the eco-warriors are having a hissy fit.
I’m very disappointed in Kaku — I’ve always been impressed with his ability to communicate future technology like, nanotech, robots, space science, etc. Sad.
The two worse so far has been physicist Michio Kaku [ad hom deleted]saying that these reactors were… …on the verge of going into a “China Syndrome meltdown,” at any moment…
Given the location, shouldn’t that be an “America Syndrome”?
I’m about to go into Channel 9 TV studios to talk about the nuclear plant/earthquake situation at 5:30pm tonight (AEDT). Will also be on the Ch9 morning show at 8:15am tomorrow (different interview).
Here are a couple of good ones!
http://www.reuters.com/article/2011/03/12/us-japan-quake-nuclear-us-analysis-idUSTRE72B04C20110312
Snap analysis: Japan may have hours to prevent nuclear meltdown
As I understand it they also have batteries for pumping coolant.
Some of the comments I have seen around blogs and social media demonstrate the level of ignorance that exists. A wave of high speed H2O caused by nature kills probably over 1000 people and you get comments like “the biggest concern regarding this earth quake is those nuclear reactors”. I’ve been doing my bit to try and set people straight.
Obviously getting these reactors back online as quick as possible is going to be important for the general rebuilding effort. From the perspective of energy security there will potentialy be some lessons to be learnt. But much bigger lessons regarding oil refineries.
On a separate matter what do people make of the claims that the recent earthquake activity has been brought on by higher than usual turbulence in the sun. Presumably the mechanism proposed has something to do with some form of gravity impulse hitting the earth but I’m not sure how credible this idea is.
The battery-driven system apparently lasts for 8 hours, giving a lot of leeway. Some useful links here.
EVACUATE DENVER!!!!
If you live in Chernobyl the total radiation dose you get each year is 390 millirem. That’s natural plus residual from the accident and fire. In Denver, Colorado, the natural dose is over 1000 millirem/year. Denver gets more than 2.56 times as much radiation as Chernobyl! But Denver has a low cancer rate.
Calculate your annual radiation dose:
http://www.ans.org/pi/resources/dosechart/
Average American gets 361 millirems/year. Smokers add 280 millirems/year from lead210. Radon accounts for 200 mrem/year.
http://www.doh.wa.gov/ehp/rp/factsheets/factsheets-htm/fs10bkvsman.htm
http://www.nrc.gov/about-nrc/radiation/around-us/doses-daily-lives.html
Although radiation may cause cancers at high doses and high dose rates, currently there are no data to unequivocally establish the occurrence of cancer following exposure to low doses and dose rates — below about 10,000 mrem (100 mSv). Those people living in areas having high levels of background radiation — above 1,000 mrem (10 mSv) per year- such as Denver, Colorado have shown no adverse biological effects.
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bio-effects-radiation.html
Calculations based on data from NCRP reports show that the average level of natural background radiation (NBR) in Rocky Mountain states is 3.2 times that in Gulf Coast states. However, data from the American Cancer Society show that age-adjusted overall cancer death in Gulf Coast states is actually 1.26 times higher than in Rocky Mountain states. The difference from proportionality is a factor of 4.0. This is a clear negative correlation of NBR with overall cancer death. It is also shown that, comparing 3 Rocky Mountain states and 3 Gulf Coast states, there is a strong negative correlation of estimated lung cancer mortality with natural radon levels (factors of 5.7 to 7.5).
http://www.ncbi.nlm.nih.gov/pubmed/9753369
IAEA alert log:
Fuel rod was exposed 90cm above the water inside the reactor core at 11:40AM. Now water for fire-fighting being injected. Fukushima No. 1 NP
Nuclear plant safety committee confirmed reactor core now exposed 1.7meter above water, speculating now fuel rod has started to melt.
#Nuclear plant safety committee detected cesium, a substance that is not normally detected unless, according to an expert, fuel rod melts.
http://twitter.com/Touruma
No idea how true it is.
I hope that Twitter story is from a rumormonger, and I hope someone runs the source down and posts a followup.
The news from the official site is bad enough:
(From the update at the first link posted earlier)
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
“the company’s monitoring of Fukushima Daiichi 1 has separately shown an increase in radiation levels detected emerging from the plant via routes such as the exhaust stack and the discharge canal.
Over the last several hours evacuation orders for local residents have been incrementally increased and now cover people living within ten kilometres of the power plant.
Raised temperatures
Meanwhile at adjacent Fukushima Daini, where four reactors have been shut down safely since the earthquake hit, Tepco has notified government of another emergency status.
Unit 1′s reactor core isolation cooling system had been operating normally, and this was later supplemented by a separate make-up water condensate system. However, the latter was lost at 5.32am local time when its suppression chamber reached 100ºC. This led Tepco to notify government of another technical emergency situation.
Tepco has announced it will soon begin controlled releases to ease pressure in the containments of units 1, 2 3 and 4 at Fukushima Daini.
Higher sun turbulence and gravity effects have nothing whatsoever to do with the movement of lithospheric plates They have and will always continue to move. The stresses in the rocks build up and eventually movement occurs along the plate boundary or along an associated fault. The longer it takes for the movement to occur, the greater the ultimate movement and hence the greater the magnitude of the quake. In 1906, displacement along the San Andreas Fault measured 21feet. No wonder the city fell down and then burned. Following the Christchurch earthquake it was a pretty safe bet that there would be some other movement along the same plate boundary elsewhere. That’s what seems to have happened in Japan.
I”m calling horseshit on that “Twitter” story posted just above (Twitter itself is overcapacity now, but Google found the string posted above). It’s found at one site only, not counting this one — it’s from a self-described “UFO conspiracy fringe” site that may be an elaborate parody, it’s hard to tell. You can see it:
http://www.godlikeproductions.com/forum1/message1388942/pg32
0548: The plant’s operator, the Tokyo Electric Power Company, tells AFP: “We believe the reactor is not melting down or cracking. We are trying to raise the water level.”
http://www.bbc.co.uk/news/world-middle-east-12307698
I suppose the twitter thing was BS.
It sounded like it to me, though a temporary drop in water level was plausible
“1. I noticed that they “lost” the diesel backup units about the same time the tsunami hit the plant locations. Is it possible the debris from the tsunami jammed the cooling pump filters and intakes? What good would the backup electric system be, if the cooling water supply is blocked? It seems that they should have an alternative emergency cooling system in place.”
You’re thinking of the tertiary cooling system, the heatsink for the heat engine, which exchanges waste heat from the turbine out to seawater.
This is completely different from the water that actually cools the reactor, and these reactor cooling systems aren’t dependent on drawing water in from an outside source.
Yeah, and something’s definitely not good at “Fukushima Daiichi 1″ — the few Google hits on that plus “discharge canal” don’t explain what that means.
Here’s an earlier problem report-with diagram of the cooling system-that mentions but again doesn’t identify the “discharge canal” as an improper failure mode:
http://www2.jnes.go.jp/atom-db/en/trouble/individ/power/f/f20060811/news.html
The second diagram in that document does show a “discharge canal” common to all the reactors — it’s meant to carry away water from storm drains.
I did a search on the ‘exposed fuel rods’ and the story only comes up on tweets,[ad hom deleted] our friends at CNNGo said this…
http://www.cnngo.com/tokyo/life/quake-leaves-tokyo-ites-stranded-546457
“The top issue on everyone’s mind as of Saturday afternoon involves the Fukushima #1 Nuclear Reactor, which is reportedly leaking radioactive material in a situation highly suggestive of a meltdown. The dangerous conditions preclude direct observation, and citizens are anxiously awaiting further reports.
According to NHK, the state news channel, one of the reactor’s fuel rod bundles has cracked, and the tips exposed by some 50 – 90 cm due to evaporation of the cooling pond. The surrounding area has subsequently been evacuated to a distance of 10 km”
BWHAHAHAHAHAHAAAAAAAAAAA!
That was a good trick! Getting the cooling ponds INSIDE the reactors!
Paul, do you have a link to any of those press releases?
BTW, if the fuel partially melts, that’s a completely different situation to a containment breach.
You’re thinking of the tertiary cooling system, the heatsink for the heat engine, which exchanges waste heat from the turbine out to seawater.
Strictly speaking, I believe BWRs don’t have a tertiary loop. The primary loop in a BWR drives the turbine directly, so the secondary loop is the one which draws on the heat sink.
Interesting that the Japanese nuclear authorities continue to talk about possibilities that the pundits on this site have already dismissed.
I don’t dismiss the possibility of a Three Mile Island-style meltdown if they’re unable to provide proper cooling. Given the containment in these reactors, I very much doubt the possibility of a Chernobyl-style release.
Paul, what press release, where? Link or description please?
Google News does not find what you posted. The top hit for regular Google quoting from what you posted is the same UFO/conspiracy site I mentioned above — now at the top of the first page of hits so it’s getting propagated wildly. The second hit is the Huffington Post, home of the anti-vaccine wackywoo and other nitwittery.
So two crap sources and no news sources.
What source are you relying on? Why do you trust it to be giving good information? What is your source quoting from? Pointers, links, please.
“Trust, but verify.”
Reposting what I posted last night in the earlier thread: Here are diagrams of the various reactor types in use: http://www.ansn-jp.org/jneslibrary/npp2.pdf
Details here -if you can figure out which type is being discussed; these plants have several different designs. I _think_ the big problem is the Fukushima I-1 model, judging by the date in the timeline.
That had a simple single-loop cooling system — the one where when the condensate water pool hits 100C (starts to boil) then it’s no longer cooling the primary loop.
Another part of this doc says the condensate pools were using sea water. I don’t find a diagram of that.
“After driving a turbine, the steam is converted into water with a condenser (cooled by sea water in Japan), and pumped into the reactor vessel with feedwater pumps. A part of the water is sent into the reactor vessel after being pressurized with recirculation pumps installed outside of the vessel and fed into the reactor core from the bottom part of the reactor vessel with jet pumps.
Inside of a BWR reactor pressure vessel (RPV), feedwater enters through nozzles high on the vessel, well above the top of the nuclear fuel assemblies (these nuclear fuel assemblies constitute the “core”) but below the water level. The feedwater is pumped into the RPV from the condensers located underneath the low pressure turbines and after going through feedwater heaters that raise its temperature using extraction steam from various turbine stages.
The feedwater enters into the downcomer region and combines with water exiting the water separators. The feedwater subcools the saturated water from the steam separators. This water now flows down the downcomer region, which is separated from the core by a tall shroud. The water then goes through either jet pumps or reactor internal pumps that provide additional pumping power (hydraulic head). The water now makes a 180 degree turn and moves up through the lower core plate into the nuclear core where the fuel elements heat the water. When the flow moves out of the core through the upper core plate, about 12–15% of the volume of the flow is saturated steam….”
Several sources including Reuter.
Here is a Dow Jones version:
http://e.nikkei.com/e/fr/tnks/Nni20110312D12JF421.htm
Here is a MarketWatch commentary:
March 12, 2011, 12:42 a.m. EST
Japan warns of meltdown at quake-hit plant: Kyodo
TOKYO (MarketWatch) — Japanese nuclear authorities warned of a meltdown Saturday of the core of a nuclear reactor at a plant in Fukushima operated by Tokyo Electric Power Corp. /quotes/comstock/64e!9501 (JP:9501 2,121, -32.00, -1.49%) , also known as Tepco, according to Kyodo News. Authorities said that there was a high possibility that nuclear fuel rods at the reactor of Tepco’s Daiichi plant may be melting or have melted, Reuters reported, citing Jiji news. The Daiichi No. 1 nuclear reactor is about 240 kilometers (150 miles) north of Tokyo. Friday’s 8.9-magnitude earthquake damaged the plant’s cooling mechanism, leading to overheating that reportedly damaged the fuel rods in the reactor’s core.
Not saying it’s correct, but here’s sources for Paul’s stories
http://www.vancouversun.com/Quake+nuke+plant+meltdown+Japan+media/4427671/story.html
“Kyodo News agency said radioactive caesium had been detected near Fukushima plant, citing the Japanese nuclear safety commission.”
http://www.channelnewsasia.com/stories/afp_asiapacific/view/1116036/1/.html
“Japan’s nuclear authorities warned Saturday that quake-hit atomic plant Fukushima No. 1, about 250 kilometres (160 miles) northeast of Tokyo, “may be experiencing a nuclear meltdown”, media said.”
link for MarketWatch story:
http://www.marketwatch.com/story/japan-warns-of-meltdown-at-quake-hit-plant-kyodo-2011-03-12
Just caught Barry on WIN News. It went OK then senior newsman Peter Harvey chimed in with an upbeat assessment ridiculing the Chernobyl comparison. Let’s hope it falls well short of TMI.
Now officials claim cesium has been detected, indicating some fuel rods have melted.
Just saw Barry’s appearance on channel 9. What a cool, level headed, sensible response to questions on the situation. Exceptionally well done.
Just saw Barry on the TV interview. He put the scare stories to bed pretty comprehensively. The newsreaders definitely thought so too. His analogy of the amount of radiation that anyone would receive standing outside the reactor for 100 days being equal to one chest x-ray was brilliant and put it in real perspective for anyone listening who was worried about the situation. He didn’t have much air time but also managed to convey that the evacuation of the areas was merely following procedural protocol arounf nuclear power plants and not indicative of a probable catastrophe.
A bit more from that same ansn-jp.org document:
“(2) Heat transfer and power control
The heat generated in fuel rods is transferred to the reactor coolant. The magnitude of heat transferred according to the temperature difference between the heat transfer surface and the coolant has been obtained in many experiments. Since the heat transfer decreases in the transition film-boiling region in which the boiling becomes violent that could cause a burnout of fuel cladding tube, the heat transfer in the nucleate-boiling region is utilized in BWR. Therefore, the reactor operation limits are imposed on BWRs not to approach to the transition film-boiling region during normal operation and abnormal operational transients….”
…
… In contrast to the pressurized water reactors that utilize a primary and secondary loop, in civilian BWRs the steam going to the turbine that powers the electrical generator is produced in the reactor core rather than in steam generators or heat exchangers. There is just a single circuit in a civilian BWR in which the water is at lower pressure (about 75 times atmospheric pressure) compared to a PWR so that it boils in the core at about 285°C. The reactor is designed to operate with steam comprising 12 to 15% of the volume of the two-phase coolant flow (the “void fraction”) in the top part of the core, resulting in less moderation, lower neutron efficiency and lower power density than in the bottom part of the core….
…
… Changing (increasing or decreasing) the flow of water through the core is the normal and convenient method for controlling power. When operating on the so-called “100% rod line,” power may be varied from approximately 70% to 100% of rated power by changing the reactor recirculation flow by varying the speed of the recirculation pumps. As flow of water through the core is increased, steam bubbles (“voids”) are more quickly removed from the core, the amount of liquid water in the core increases, neutron moderation increases, more neutrons are slowed down to be absorbed by the fuel, and reactor power increases. As flow of water through the core is decreased, steam voids remain longer in the core, the amount of liquid water in the core decreases, neutron moderation decreases, fewer neutrons are slowed down to be absorbed by the fuel, and reactor power decreases.
Steam produced in the reactor core passes through steam separators and dryer plates above the core and then directly to the turbine, which is part of the reactor circuit. Because the water around the core of a reactor is always contaminated with traces of radionuclides, the turbine must be shielded during normal operation, and radiological protection must be provided during maintenance. Most of the radioactivity in the water is very short-lived (mostly N-16, with a 7 second half life), so the turbine hall can be entered soon after the reactor is shut down.”
NYT puts a name on the quotes:
http://www.nytimes.com/2011/03/13/world/asia/13nuclear.html
“Ryohei Shiomi, an official with Japan’s nuclear safety commission, said that a meltdown was possible at one of the two Daiichi reactors, The Associated Press reported. Japanese television reported that the country’s Nuclear and Industry Safety Agency said it had detected cesium near one of those reactors.
Naoto Sekimura, a professor at Tokyo University, told NHK, Japan’s public broadcaster, that “only a small portion of the fuel has been melted….”
——-
No press release at the TEPCO site, here’s the page to check for their news releases:
http://www.tepco.co.jp/en/press/corp-com/release/index-e.html
PaulK2
There are a lot of ifs in the report you linked
“Hideyuki Ban, the co-director of Citizens’ Nuclear Information Center, said, “The Japanese government’s Nuclear and Industrial Safety Agency has said that if the water level can be raised to cover the fuel rods, they can keep the situation under control, but if the water cannot cover the fuel, the damage will become more severe, and that means radioactive materials will be released.”
“If damage expands, cesium or other radioactive materials may be released not only inside the containment dome but also into the environment,” he said.”
This seems to have produced misquoting on some other sites to the point where cesium HAS been released. Surely you know how a story changes as it passes from mouth to mouth. Let’s wait for official confirmation by the appropriate authorities shall we?
Wikipedia’s
http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant
got the info needed to identify the model of the reactor:
Fukushima I – 1 BWR March 26, 1971 460 MW
So that does seem to be the very earliest design described in that PDF I linked above.
And if you look at the footnotes to the Wikipedia article, if you can read Japanese, they actually cite sources for the stories and link to them. Good.
This info: “During the afternoon of March 12, the Nuclear and Industrial Safety Agency announced that part of a cesium rod appeared to have melted, but the NHK reported that the rest of the fuel had cooled and there was no reason for alarm.[24]”
This source:
http://www3.nhk.or.jp/news/html/20110312/t10014623511000.html
“part of a cesium rod” has to be someone’s mangled translation — can anyone improve on that?
If cesium has been detected in the coolant water, then the integrity of at least some of the fuel rods has been breached. Given the information that the coolant is only covering the bottom 2/3 of the fuel rods, it shouldn’t take long for the structural integrity of the top portion of the fuel rods to fail.
If the fuel rods fail and fall, will the control rods still be able to control the reactor?
Now this from Business Week — which I doubt makes sense:
http://www.businessweek.com/news/2011-03-12/japan-reactor-rods-may-have-started-to-melt-agency-says.html
“Tokyo Electric earlier said …. Temperatures in the control room rose to higher than 100 Celsius (212 Fahrenheit), said Naoki Tsunoda, a company spokesman.”
Hard to believe that’s right. 100 C is the temperature given earlier as a problem for the condensing water pool. But the control room??
Can’t be right. That’s nightmare material.
I’m beginning to wonder if some of these contradictory and nonsensical reports aren’t the result of hasty and botched translation.
> Given the information that the coolant is only
> covering the bottom 2/3 of the fuel rods
Given that? By whom? Where? “Press releases say” is not a source. Sources, man, give us your sources. Otherwise you’re just copypasting stories and that makes everyone dumber.
Take the “100 C” report above. What’s boiling temperature? Look before that for the “evaporation of the cooling pond” — now that makes sense, and it is indeed on the path to a major failure.
Could happen. But they had not triggered the last-ditch emergency cooling system — at last report.
There’s nothing about this in any press release file I can find. If it’s true, someone will know where the story started.
Ask who says and where you can check.
> botched translation
You bet. [ad hom deleted]Plus the honestly fearful who don’t know how to look stuff up.
Seriously, if you read Japanese, please look at the Japanese sources that Wikipedia cites and help us out — heck, help Wikipedia out with better translations.
Suspending venting due to high radiation level in the vented gases:
Venting air from reactor container suspended
The operation at Fukushima No.1 plant to lower pressure of the containment vessel has been suspended due to high radiation levels at the site.
http://www3.nhk.or.jp/daily/english/12_38.html
Pressure of the reactor container is rising as its cooling system became dysfunctional due to a blackout and power generator breakdown. This has raised concern about possible damage to the container.
The power station’s operator, Tokyo Electric Power Company, began to vent air from the reactor container at 9AM on Saturday.
Under the plan, 2 valves close to the container would be opened manually, but radiation level on the second valve was found higher than expected.
The operation has been suspended because of the possibility that workers could be exposed to radiation. The utility is reportedly studying how to open the valve by replacing workers at a short interval, or using electric remote control.
The Nuclear and Industrial Safety Agency says if radioactive substance is released in the air, safety of residents evacuated beyond a 10-kilometer radius from the No.1 reactor will be ensured.
Saturday, March 12, 2011 13:09 +0900 (JST)
Ok, thank you Paul K2, that’s …. damned scary.
And from a real source with more cites attached.
Bad news. But real news. Much appreciated.
Paul, the reactor is already subcritical and the control rods are home. NOTHING will restart the reaction now.
I just wrote this in response to a friend who said this via email:
1. The reactors shut off in the event of a situation like this – control rods are dropped. Power levels drop to about 5%.
2. The plant is then no longer generating electricity and requires and external source such as a diesel generator to provide power to pumps.
3. The tsunami seems to have damaged the diesel generators, so they had to fly in some new backup power units.
4. The meltdown risk is if too much steam is vented from the primary circuit such that the fuel rods are exposed. This may have happened for a short time, leading to some melt of the clad (due to decay heat from the fission
products) but nothing is confirmed at this stage (i.e. nothing from TEPCO).
5. AP1000 has additional systems to make this less likely.
6. Such a potential situation (fuel melt due to loss of coolant via venting) could not happen in the IFR as the fuel would remain passively cooled by the sodium.
I missed Barry. Bummer. Turned on the 17:30 news (in Brisbane) and I just got a reference. Ziggy got a good few minutes and spoke well on the performance of the safety systems.
Dow Jones is source for information on 1/3 of fuel rods exposed (I posted link earlier):
Saturday, March 12, 2011
Nuclear Authorities: Nuclear Reactor Facing Threat Of Meltdown
TOKYO (Dow Jones)-Japanese nuclear authorities said Saturday afternoon the Fukushima Daiichi No. 1 nuclear reactor was experiencing the threat of a meltdown after Friday’s massive earthquake damaged the cooling system and that outside water was being poured into the reactor to cool it down.
“If the water level remains at this level, the reactor core might be damaged, but we are now pouring water into the reactor to prevent it from happening,” a spokesman for Tokyo Electric Power Co. (9501) told Dow Jones Newswires. TEPCO is the owner of the plant, which is located 150 miles, or 240 kilometers, away from Tokyo.
A portion of the reactor’s fuel rods, which create heat through a nuclear reaction, have become exposed due to the cooling-system failure. The spokesman for TEPCO said 1.5 meters of the 4.5 meter long fuel rods were potentially exposed.
Loss of cooling water resulted in a near meltdown of the Three Mile Island reactor in Pennsylvania in 1979, the worst nuclear incident in U.S. history.
If coolant isn’t restored, extreme heat can melt through the reactor vessel and result in a radioactive release. Reactors have containment domes to catch any release. But there is always the chance that an earthquake could create cracks or other breaches in that containment system.
Hideyuki Ban, the co-director of Citizens’ Nuclear Information Center, said, “The Japanese government’s Nuclear and Industrial Safety Agency has said that if the water level can be raised to cover the fuel rods, they can keep the situation under control, but if the water cannot cover the fuel, the damage will become more severe, and that means radioactive materials will be released.”
“If damage expands, cesium or other radioactive materials may be released not only inside the containment dome but also into the environment,” he said.
My wife, Sonomi, is from Tokyo by the way. For people who’ve been asking me about whether her immediate family are okay — yes, as far as we know everyone is fine, thank goodness.
Update from TEPCO:
Remember that there are two Fukushima nuclear power stations. Daini and Daiichi.
“All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.
Unit 1(Shut down)
– Reactor has been shut down and steam in reactor has been cooled by isolation condenser, but it is now stopped. Because pressure level in reactor containment vessel is increasing, following the national government instruction, we are implementing a measure to reduce the pressure of the reactor containment vessels in order to fully secure safety.
Reactor water level is decreasing, we will continue injecting water step by step.
http://www.tepco.co.jp/en/press/corp-com/release/11031219-e.html “
Thanks Barry for bypassing the “Major Media” with their [ad hom deleted] such as Michio Kaku.
Speaking as a professional scientist, I support DV8XL’s assessment of Kaku. Much as I love the documentaries on the Discovery channels, I cringe when they feature Kaku [ad hom deleted].
When the dust settles, I expect your credibility will shine compared to the likes of him.
Interesting image:
http://uvdiv.blogspot.com/2011/03/some-links-on-fukushima-daiichi-1.html
Whoops….
CH9 just got a LOT worse. 18:30 news.
“Frantically trying to avoid a catastrophic MELT DOWN”.
“RADIATION levels over 1000 times over the SAFE threshold”
“PEOPLE evacuated as DEADLY RADIOACTIVE GAS is vented into the atmosphere”
Sheesh…..
Quite amazing,[ad hom deleted] who appear out of the woodwork in a situation like this. I saw the same thing on The Oil Drum when the Deepwater Horizon exploded.
Most of the comments then were complete and utter crap.This Japan earthquake is the same sort of situation only we have the antinuclear propagandists trying to cash in.
Kiddies,why not just let the situation clarify and then draw conclusions. It seems to me that the Japanese reactors are in competent hands,even in an emergency like this.
A lot of updates have now been made to the top post, people may wish to re-read this for a further summary of the situation.
To answer some disputes in this thread
There are two parts of the Fukushima plant, separated by a few miles. Daiichi (1) has 6 reactors (three were out for maintenance), and Daini (2) has 4.
Fukushima Daiichi #1 (first phase, first reactor) is a GE BWR/3. IAEA publishes a table of these things:
http://www-pub.iaea.org/MTCD/publications/PDF/CNPP2010_CD/pages/AnnexII/tables/table2.htm
I think it has a Mark 1 containment (should double check this)
Reputable sources are reporting cesium detected outdoors, e.g. the NY Times:
http://www.nytimes.com/2011/03/13/world/asia/13nuclear.html?_r=1&hp=&pagewanted=all
(But I do not believe (though I am no expert) that fuel must melt for cesium to be released — I think fuel rod rupture is enough.)
The claims of 100 °C control room temperatures are obvious mistranslations. If you cross-check with TEPCO press releases, that temperature probably refers to the pressure supression vessel.
Reports that fuel rods were exposed are scattered and seem unreliable.
http://e.nikkei.com/e/fr/tnks/Nni20110312D12JF423.htm
“…said one observer”
I presume the reports of an “explosion” were from this:
http://www.twitvid.com/LICNU
If you can’t view the video then it looks like a large amount of steam (or grey gas for that matter) coming near or at the reactor.
0:48
???
YouTube content removed Scott, as ‘spam/ scam / commercially deceptive content’.
If it is an explosion at the plant, it’s going to have happened to a secondary or tertiary system, not the reactor containment building.
I retract part of my comment, this seems solid:
“The agency said there was a strong possibility that the small amount of radioactive cesium monitors detected was caused by the melting of a fuel rod at the plant, adding that engineers were continuing to cool the fuel rods by pumping water around them.”
http://www.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclear/
Also, some kind of explosion just happened.
The plant owner, TEPCO, reports an explosion at Fukishima with worker injuries, as the Fukishima nuclear accident continues.
It was not a spam / scam or commercially deceptive content. The same footage has been repeated over and over again on BBC live.
http://www.bbc.co.uk/news/world-middle-east-12307698
The building around reactor 1 exploded. Watch BBC.
I’ve linked to the BBC story/video as point 8 in the top post.
What caused the explosion is the question. I hope it’s not hydrogen gas, because we can all see the implications of that happening…
The head of the finnish regulatory agency STUK has just commented the situation in Japan and he thinks this will be the worst nuclear accident after Chernobyl. He says there was a hydrogen explosion and since the reactor is so old the containment building is insufficient [unsubstatiated personal opinion deleted] The rescue effort will continue for months.
Unfortunately as with Christchurch structure collapses the Fukushima nuclear has become critical as well as the ‘quake releasing 8,000 times the energy of Christchurch shallow event; generation of damage seems to be continuing and any knowledge of structures would tell one that is a bad situation. 7.2 6.6 last night UK time 8.9 and many small events continuing.Our thoughts with Japan nuclear and safety officers. Mike
..Futhermore Mr Laaksonen (head of stuk) strongly criticized the insufficient planning with respect to the loss of grid power to run the cooling. He felt that this was a weakness that japanese were well aware of, but had not yet tackled. He also mentioned that USA has several old nuclear power plants with similar weaknesses.
The lack of information coming out of the Fukishima-Daiichi plant is worrisome. It may indicate the command structure at the facility has been decimated. At this point it is unlikely that the plant control systems and personnel are still intact.
Since the coolant systems seemed to be under manual control prior to the accident, how the plant will be controlled at this point is highly questionable.
@ Jani-Petri Martikainen
How absurd is this situation? How long the cooling system (via turbine spin down) could run with loss of power was exactly the experiment they were running at Chernobyl!
Why is it the issue hasn’t been addressed comprehensively at every single NPP?
@esquilax
My thoughts exactly. Modern NPP:s are designed so that even core meltdown can be controlled (to some extent), but why all old NPPs have not been upgraded to better standards is absurd.
esquilax,
The cooling system at no western nuclear plant is ran by the turbines spinning down. i.e. this failure has NOTHING to do with Chernobyl. The cooling systems can be ran for 8 hours on batteries (which is what they did ), off-site power or diesel generators.
@Scott While you are correct, that is is not similar to Chernobyl, the faith put on the diesel generators has been proven faulty. What I understood is that the NPP was not properly setup to quickly switch to off-site generators when osite ones failed.
Can someone explain in simple terms what these statements mean;
a ‘nationwide atomic alert’ + “The plant is experiencing a nuclear meltdown”
http://economictimes.indiatimes.com/news/politics/nation/latest-news-of-japan-fukushima-nuclear-reactor-explodes-leading-to-radiation-leakage/articleshow/7686232.cms
Agreed.
And if it is true that hydrogen caused the explosion, then why didn’t the recombiners work?
Now is the time to be trumpeting the remarkable success of nuclear power in the face of natural disaster. Such survival in the face of this most savage event, such temporary faults! Nuclear has survived its most severe test yet, confounding its naysayers and pleasing its designers.
Every hysterical assertion could be countered by referring to the much greater damage done to its rival power sources. Ask what is the condition of the brickwork around coal-fired power stations, or the railways supplying them with coal? How intact are the pipelines supplying methane to factories and homes of a hundred million people? What would be the condition of rooftop glass-covered solar panels? Where would the offshore wind turbines be now? Would the prised-open fractures of the geothermal source stay open enough to continue to supply steam?
The context of widespread damage to other structures and processes does represent a major challenge to the Japanese response. Consider for example, damage to industrial brickwork including factories, offices and homes, rupturing of pipelines including water and sewerage, the breaking of landline communications and damage to roadwork. As far as toxicity is concerned, consider the spills throughout the chemical engineering plants across Japan. They have plenty to worry about already.
However, by the time the Japanese people begin what must be a massive recovery programme, it will be nuclear energy first back on deck to power the heavy lifting.
Umm, this is where the hysteria on twitter has got to:
http://i.imgur.com/bvXcG.jpg
Let’s hope so Roger.
Understandably there is a lot of confusion going on with the various news sources misinterpreting opinions as facts…
So, more likely explosion was to do with a secondary structure than hydrogen related? I’ve seen nothing solid to the contrary at this stage, only speculation.
Roger Clifton: I don’t think you have to be a nuclear hater to realise that the industry is pretty unique in its potential for disastrous consequences should something go badly wrong. If a wind farm is destroyed, then that’s a loss to the grid and presumably the government or company that put them up. But it won’t result in a great many wind turbine-related deaths. Ditto for solar and wave — though not so much for coal or oil.
Now, in this case the great hope is that the Japanese authorities have things under control, and that the design of the reactors and the safety planning stands up. And there’s an awful lot of hysteria out there.
That doesn’t negate basic concerns about nuclear energy.
News coming in indicates that this was an ignition of hydrogen, which caused the explosion and collapse of the roof of the outer reactor building. I strongly suspect that the steel reactor vessel remains intact, which is good news. This is an older design, where the containment is fully internal , rather than being part of the external building shell. Look at the diagram I’ve included in the top post (via Capacity Factor), and you can get a better idea of what I mean.
“World Nuclear Association comms dir says blast due to hydrogen igniting, may not necessarily have caused radiation leakage”
from twitter. Any confirmation?
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
It’s difficult to tell exactly what’s happening in the explosion vid. It seems to me as if the explosion may have been centred on the turbine hall rather than the reactor containment building.
Of course, in a BWR, the primary coolant loop connects both of these.
The Japanese authorities have extended the evacuation zone to 20km.
Latest Alert from Stratfor – yikes.
http://www.stratfor.com/analysis/20110312-red-alert-nuclear-meltdown-quake-damaged-japanese-plant
@Barry
Let’s hope your hunch is right. But I am still worried. I regard our regulatory agency STUK highly.They are not anti-nuclear crazies and know what they are talking about.
just read a colleques update. More than 1000mSv/hour reported outsite Daiichi.
That’s micro, not millisieverts. I’ve not seen this confirmed.
Are we sure that the exposure is 1 Sv/hour?
The 50/30 LD is 4-5 Sv ‘in a short period’.
24 Sv/pd is a HUGE amount of exposure. You could consider that 98/30 LD.
I suspect the Hydrogen explosion is tied to attempting to vent the containment using Reactor Building Ventilation. Possibly a duct rupture.
Also if they had containment hyrdrogen recominers they likely did not have power to operate them. The video sure appears to be a Reactor Building explosion. Turbine structure would be the lower height building.
Thanks and well done Barry. Much attention given to controlled venting from nuclear power stations. Acrid plumes of smoke from burning oil refineries does not seem to raise eyebrows. Nuclear is still a sexy hazard, quite clearly. Keep the facts coming, we need them.
Honestly, anyone claiming “victory” from any side of the argument on this less than 48 hours after the earthquake is just plain silly. Anyone who claims they know exactly what has happened and will happen from here is either guessing, lying, or both.
right, mea culpa. not Sv/hour of course. Sorry.
http://www.bbc.co.uk/news/world-asia-pacific-12720219
Good explanation of what has happened here. I also just heard on the live feed from BBC news that the radiation levels have come down around the reactor and there is no serious problem.
Here is the report from the BBC website:
“Government spokesman says the nuclear reactor container at the Fukushima-Daiichi plant has not been damaged, and the level of radiation has dropped following the explosion earlier on Saturday, AFP reports.”
CNN confirming venting of containment was in progress prior to explosion… Confirms my idea that it was a hydrogen explosion due to venting that destroyed the reactor building.
Latest report
http://www.abc.net.au/news/stories/2011/03/12/3162554.htm?section=justin
I’m not convinced the explosion was centred on the reactor building. From what I can make out, it looks as if the explosion starts behind the squarish containment building, and much of the cloud emerged from where the turbine hall would be.
I could be wrong, and it may well have been a hydrogen explosion in any case.
Is it confirmed that the reactor building was destroyed? It seems largely intact in the video even after the explosion.
http://i.imgur.com/CckjP.jpg
To me, it looks like only the top metal shroud bit may of been destroyed.
Boy, did I pick the wrong time to come back to the discussion on NP.
Even though a series of aging NPPs survived a massive earthquake, even though no serious amount of radiation was released, and no one will be killed, i’m worried this might be the end. People may simply read headlines like ‘Is this another Chernobyl’ and their views on nuclear power may be seriously tainted, all over the world.
From what I can see in the pictures, similar reactor designs and reports. It is the reactor building. If it was just the interface (steam tunnel) it would be only the side back towards the lower building.
Lets just hope they can continue to inject what they can and the containment was not damaged.
Need power to flood up the containment using ECCS pumps (large volume) and/or initiate suppression pool cooling to allow SRV flow cooling to be become effective again. It takes alot of water if they must flood the containment for cooling.
I’d say if rad levels are dropping, the contaiment is likely still in tact with some fuel failure having occurred.
I doubt it Huw. When the dust settles, people will realise how well the Japanese reactors — even the 40 year old one — stood up to this incredibly energetic earthquake event. Meanwhile, China, India, Korea etc. will keep building lots of reactors. Those who don’t, well, they’ll continue to be utterly wedded to burning fossil fuels with essentially no other options. There’s this old thing called ‘reality’ that never goes away, despite how annoying it can be to some, at times.
I get a NHK feed and watched the press conference from Tokyo Electric.
1) It was a combination of steam and hydrogen that caused the explosion. What we saw wasn’t a building but a steel frame with concrete panels.
2) Nuclear container was not damaged
3) Both the radiation level and pressure inside container at reactor 1 have been steadily decreasing since the explosion.
4) Level was 1,015 microverts at the time of explosion, they been measuring the levels regularly and had dropped to 800 by 5 pm, and 600 by 7 pm.
5) They are going to let in sea water to help cool reactor 1 down.
Assuming the steel pressure vessel is intact, you’ve still got to dump residual heat from the core for a while yet. Are there still systems available for this after the explosion?
OK, what em1ss said.
Barry, I seriously hope your right. I’m just hoping this wont impact any new build plans in Europe where there arn’t any major fault lines. I’m pretty sure there’s none in Australia either.
Did anyone read that comment by Walt Patterson on the BBC article ‘This is starting to look a lot like Chernobyl’ – WHAT?! Which Chernobyl were you looking at?
Don’t forget that if the reactor escapes without releasing a huge amount of radiation, then it will be forever proven that even a 40 year old reactor can survive an 8.9 earthquake followed by a massive tsunami. It’s not the end of the world.
More here: http://news.yahoo.com/s/ap/as_japan_earthquake
I have experience with GE BWRs, emergency operating and severe accident management procedures. Though not site specific to there, they are likely very similar.
Something interesting from a friend of mine, who’s a professor of geophysics:
The recent Japanese earthquake was a very large one, large enough to be listed in the top 10 in the past century. See:
http://www.infoplease.com/ipa/A0763403.html
The largest event we ever recorded was the 1960 M9.5 or 9.6 Chilean earthquake. The 1964 Good Friday event in Alaska was quite a bit smaller at 9.2.
At the risk on sounding pedantic, I have to indicate that magnitude is a terrible way to measure the size of an earthquake. The Body wave magnitude “saturates” at about 7.5, because the wavelengths of the seismic waves used for that (1 hz P waves) is only about 10 km , so that the amplitudes are controlled by the first 10-20 km of rupture. The surface wave magnitude is based on 20 sec period Rayleigh waves, and is sensitive to a much larger portion of the initial rupture. It saturates around 8.5. After that one has to go to free oscillations of the planet (first observed in 1960), and the gravest modes have periods of 10 minutes to one hour. that will yield a very good estimate of the so-called “moment” of the earthquake. the magnitudes listed in the site above are scaled form moment estimates.
The problem is that P-waves take about 20 minutes to travel to distant seismic stations, so in the first hour after an event, magnitude estimates tend to be low. After a couple of hours, surface waves have been recorded and analyzed, and the magnitude estimate goes up if the event was big. After a couple of days, free oscillations have been recorded (they will be recorded for several weeks) and a much better magnitude becomes available…. and it can be much larger. However, this does not help with tsunami warnings, of course.
Another issue is that amplitude-based scales are not very good at telling the story. For each unit step in magnitude, the energy of the event changes by a factor of 30. So a M9.6 event is 30 times more energetic than a M8.6 event. But the number of event drops by a footer of 10 for each increase of on unit in magnitude. Thus it is practically impossible to implement a scheme to “relieve stress” by triggering numerous events of acceptable size. It would take 27,000 M5.6 events to equate a M8.6 one, yet only 1,000 occur in nature.
It is now possible to use continuously recording GPS stations to get an estimation of the static displacement (zero-frequency) in real time. This is not yet done operationally, unfortunately.
look at the solutions derived by Europeans for this event at http://igscb.jpl.nasa.gov/pipermail/igsmail/2011/006350.html
This offers great promise for tsunami warnings and immediate reaction to very large events.
Finally, the problems with reactor safety require knowing the actual spectrum of the vibrations. Large structures can be damaged by relatively “low” frequency shaking, while pipes, etc may have resonances at much higher frequencies. Even a relatively small event can be very dangerous, of course, if it is close enough and pumps much energy into critical frequencies. A big difference with large events is that the shaking duration is much longer so that fatigue issues become important.
I’m adding my name to this group to monitor how this event will affect the NRC approval time process time for STP 3 and 4 which has already been delayed 18 months to review a redesign that was initiated because of an NRC concern about terrorism. That concern led to an increased thickness of the containment vessel. However the NRC said that the increased weight causes an earthquake problem and wants the extra 18 months to review the new design change. Now that the earthquake and tsunami have happened we are likely to see even more delays. This is reminiscent of delays in the 1980′s. I thought we were past that problem but apparently not.
AP update confirms reactor building.
http://hosted.ap.org/dynamic/stories/A/AS_JAPAN_EARTHQUAKE?SITE=AP&SECTION=HOME&TEMPLATE=DEFAULT&CTIME=2011-03-12-03-29-13
Japan Chief Cabinet Secretary Yukio Edano:
http://www.reuters.com/article/2011/03/12/japan-quake-reactor-idAFTKZ00680620110312
They are going to flood the reactor containment with seawater!
You flood it with whatever you can if you can’t re-establish cooling to the suppression pool and ultimately the reactor….
“Edano said it would take about five to 10 hours to fill the reactor core with sea water and around 10 days to complete the process.”
What process will take the 10 days? Decay heat to reduce?
Likely using portable pumps for the seawater with limited capacity. If the core stays covered and they keep adding water it will be cooled.
Pump ideally to vessel and open an SRV to containment. Increases size of pool volume for those that understand pool boiling calculations.
While this is going on I’m sure they will try and get power back to use the larger volume ECCS pumps if not damaged to move water and establish real cooling.
Covering the damaged fuel also allows for some scrubbing of the fission product gases that you must vent while flooding.
i have posted on Nuclear Green a very preliminary assessment of the some nuclear safety issues posed by the Fukushima Dai-ichi explosion, and the possibility of further safety related events. Some recent reactor designs, notably the AP-1000, are likely to have survived the earthquake with passive cooling systems in tact. Other designs are more questionable. Among potential Generation IV reactor designs, Molten Salt Reactors are likely to perform very well in similar situations.
http://nucleargreen.blogspot.com/2011/03/nuclear-safety-and-fukushima-dai-ichi.html
OMG, I almost can not believe what I just read. Please comment on this article. She can not be allowed to get away with this level of distortion!
http://www.cnduk.org/index.php/kate-hudson-s-blog/fukushima-another-chernobyl-1008.html
Decay heat will start dropping after about 3 days from the shutdown and be easily manable after about a week.
Cesnium and Iodine are fission product gases and indicate fuel cladding failure of some degree. Facts are the levels are dropping as venting is stopped so that’s good. Levels don’t appear to be that of gross cladding failure.
Iodine is bad as it concentrates in your thyroid which is why they dispense Iodine tablets. Try to saturate the thyroid with non radioactive Iodine so you don’t load up the activated Iodine.
esquilax please settle down with the histrionics and could you try to be a little more mature?
Not only are the radiation and pressure slowly decreasing the container is intact. They did deal with the heat issue by venting the steam.
And now they’re using sea water to help it cool as well.
in the reuters article, there was mention of boric acid to prevent criticality.
I thought a criticality accident was ruled out with water moderated reactors. is there a failure to distinguish criticality accidents (chernobyl, right?) from LOCAs?
Nikkiei, they vented the containment to prevent containment failure due to overpressure. Once they lost suppression capability due to temperature of the suppression pool, containment pressure had to follow temperature. It is better to release a small amount of gas to relieve pressure, than fail the containment and release forever….
I’m not sure why they are borating, unless possibly some control rods failed to insert. Failure of more than one to insert would by standard procedure require boration to ensure shutdown margin when fully cooled down worst case. Or they are just overkilling by borating.
Don’t confuse the fact that a voided core, loss of moderator will shutdown the reaction but with certain fuel damage. You want to keep the fuel covered and cool to limit fuel damage. Voiding the core is the ultimate poison but will melt the fuel too.
[…] goes into meltdown. If you’re feeling super-nervous about the situation, please check out the Brave New Climate blog, which dispels fact versus fiction about the relevant nuclear […]
As a professional physicist, I am stunned by two things about this thread. The first is the degree of complacency exhibited by nuclear proponents, [unsubstantiated personal opinion deleted]Complacency in designers of any critical system is a very bad thing. The second is the [unsubstantiated personal opinion deleted] eminating from those apparently against next gen nuclear and the rush to sensationalism. As an independent I have been stunned to see nuclear plant operations so ‘easily’ compromised and the situation progress to a hydrogen explosion. None of that is normal and should not occur in the current situation. Tsunami and large eathquakes were design requirements and the plants have not met those requirements. if next gen nuclear is to be acepted then the industry and its experts need to put the complacency away and operate/design instead with a healthy dread for nuclear fission. We expect nothing less of you.
Source: http://blogs.aljazeera.net/live/asia/live-blog-japan-earthquake
The operator of the Fukushima nuclear power plant, Tokyo Electric Power Co, will fill the leaking reactor with sea water to cool it down and reduce pressure in the unit, a government spokesman says. Cabinet secretary Yukio Edano said:
The nuclear reactor is surrounded by a steel reactor container, which is then surrounded by a concrete building.
The concrete building collapsed. We found out that the reactor container inside didn’t explode.
Authorities earlier warned of a reactor meltdown at the reactor, damaged when a massive earthquake and tsunami struck the northeast coast, but said the risk of radiation contamination was small.
We’ve confirmed that the reactor container was not damaged. The explosion didn’t occur inside the reactor container. As such there was no large amount of radiation leakage outside.
At this point, there has been no major change to the level of radiation leakage outside, so we’d like everyone to respond calmly.
We’ve decided to fill the reactor container with sea water. Trade minister Kaieda has instructed us to do so. By doing this, we will use boric acid to prevent criticality.
It is expected to take between five and ten hours to fill the reactor core with sea water – and around ten days to complete the process.
Edano said due to the falling level of cooling water, hydrogen was generated and that leaked to the space between the building and the container and the explosion happened when the hydrogen mixed with oxygen there.
Factbox – Experts comment on explosion at Japan nuclear plant (some excellent and informative quotes): http://goo.gl/XknbV
If this is truely a Mark 1 Containment (Torus) they likely had a direct vent from the Torus to the stack. This was a mod to the Mark 1 Containments. If my memory is correct it went to the stack via the Reactor Building ventilation system.
That would have been the way they would have tried to reduce Containment/Torus pressure once the Torus temperature got too high to condense steam from the SRVs. As they did this the H2 concentration would have risen that they were venting.
Mixed this with Reactor Building ventilation to form an explosive concentration. Without power available they likely didn’t have Reactor Building ventilation fans operating. Fans in service would have provided large volumes of air dilution of the H2 concentration. Bad situation and ultimately what likely caused the explosion.
I am not complacent about the seriousness of this event. But, they seem to be handling it text book for severe accident management. When the details emerge I’m sure they are dealing with things way beyond the design basis of the plant (station blackout + > DBA earthquake + > design Tsunami)
Can anyone speculate as to the hazard of the spent fuel pool, which as I read it was inside the concrete structure that collapsed?
Today’s Top Stories From Nuclear Townhall:
• Pressure In Fukushima Daiichi Reactor Said To Be Decreasing
• Japanese Official Says Pumping System Caused Collapse At Nuclear Plant
• TEPCO Confirms Venting Of Unit 1, ‘Reactor Not Affected’ By Explosion
• Japan To Fill Leaking Nuclear Reactor With Sea Water
• Serious Damage Unlikely To Nuclear Reactor Container
• Japanese Authorities: Explosion Did Not Occur At Fukushima Reactor
• Building Collapse, Smoke At Daiichi #1 Complex
• Japan Orders Evacuation Near 2nd Nuclear Plant
• How To Help Japan Earthquake Relief
• Japan Works To Stabilize Reactors In Wake Of Earth Shock
While I am definitively a supporter of Nuclear Power in general, Fukushima is an example of the [ad hom deleted]
of nuclear safety officials. The apparent failure of the Mark I BWR containment is not surprising, as multiple studies support the idea that a Mark I is woefully inadequate for even a DBA LOCA (look at NUREG-1150, something like 90% prob of containment failure). This has been known since the 80s, the fact that NRC keeps on re-licensing Mark I containment plants is simply unforgivable. I am truly worried that with the integrity of the drywell compromised and a apparent core melt beginning, there could be radiation release well beyond design basis.
IF it was damaged and spent fuel pool level lost, RAD levels would be sky high. That’s all I can speculate on that. There are no reports of extreme RAD levels, yet….
As long as they can keep level in the pool even without a secondary containment structure (Rx Building and it’s ventillation system), it’s not good, but it still should protect the public.
what’s DBA, James?
g
Design Basis Accident
James I haven’t seen a report that the containment failed. Please link if you have.
Let’s see how long the hysteria will last this time.
US went over to coal and gas after Three Mile Island. After Chernobyl, the rest of the world made the same.
If there is going to be an environmental disaster caused by Japans accident, this is how it will happen – more fossil fuels.
The question is, ultimately, what else was damaged in the failure of the drywell? Vital components of the ECCS (emergency core cooling system), including HPCI, LPCI and RCIC are located in the drywell, and most likely, inoperable. They could also be losing cooling water inventory via a break through the main steam line, although depending on the location of the MSLIV, they might be ok. One also has to wonder if the integrity of the suppression pool (torus) is ok, because if the drywell failed, it is highly likely that the torus is damaged. This is very dangerous, because the supression pool ventilation network, which directly connects to the primary containment, which means the primary containment is essentially connected to the atmosphere! Also it is highly likely that normal reactor pressure control is severely limited because of the destruction of the torus. Ultimately, Fukushima is in a beyond-DBA LOCA and has already began a core melt, and the radiation release will most likely be in excess of three mile island, considering the loss of containment. If they dont get reactor cooling under control (which right now is now trivial task), they could be looking at a severe core melt with penetration of the RPV.
I linked to the cabinet minister saying that the concrete building collapsed (many other sources are saying the same thing):
http://www.reuters.com/article/2011/03/12/japan-quake-reactor-idAFTKZ00680620110312
He is also quoted as saying the radiation levels did not increase post-explosion (in other links, I think they are supposed to have decreased). And the Mark I containment’s spent fuel pool is on the top level.
So how to reconcile this?
I stand by my statement. I judge it would currently be rated INES Level 4: Accident with local consequences or lower on the international nuclear event scale.
A serious accident is Level 6 or 7. As such, my statement was quantitatively precise and correct.
They’ve already started pumping in seawater.
http://online.wsj.com/article/SB10001424052748703597804576194123030511478.html
@em1ss, In order to understand the Fukushima accident, you have to understand the basics of a Mark I BWR containment. A Mark I containment has two containments, the primary containment and the secondary containment (which, I, incorrectly, but commonly refer to as the drywell). The primary containment surrounds the reactor pressure vessel (RPV) and has a torus shaped supression pool. The secondary containment (also known as reactor building) surrounds the primary containment and contains the ECCS and spent fuel pools, from what I can tell from the news reports, this is what has failed in the explosion and it most likely damaged the torus as well.
I know TEPCO claims they are pumping in seawater, but how? through what systems? I would be shocked if either HPCI and LPCI are operable
I understood that Edano’s statement ruled this out? They concluded there was no break in containment, because there was no increase in radioactivity outside… (right?)
The radiation levels outside the plant are reading 100 millirem an hour and increasing! Fission products have also been detected, including cs-137. which indicates damage to the fuel.
James: please link to the article that says 100 mrem/hr and increasing.
Was this before or after the building collapse?
alright my mistake, I admit it, I apologize. The rad levels outside are reading 7 mrem an hour not a hundred. Obviously, big diffrence, but still a signifcant leak of radiation (1000 times normal) .
http://today.msnbc.msn.com/id/42025882/ns/world_news-asiapacific/
Actually I was right:
“According to the Fukushima prefectural government, the hourly radiation from the plant reached 1,015 microsievert [0.1015 rem] – an amount equivalent to that allowable for ordinary people in one year.”
http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant (citation there)
[…] daños en el edificio contenedor interior durante la explosión. Otro repaso a los hechos: Japanese nuclear reactors and the 11 March 2011 earthquake en Brave New […]
Sorry about the confusion
the 105 millirem an hours is after the explosion
Half right, I think. The level seems to be decreasing, not increasing:
Edano said the radiation around the Fukushima Dai-ichi plant had not risen after the blast, but had in fact decreased.
http://news.yahoo.com/s/ap/as_japan_earthquake
James, my first SRO certification was on a Mark 1 containment. I fully understand the Torus and the Drywell Primary Containment. The Torus is similar to the Suppression pool used on later GE BWR designs.
The safety issue is total size for a Mark 1 containment and ultimately heat removal capability. Hence why most Mark 1 plants are relatively small in thermal capacity.
Secondary Containment is as you said the Reactor Building and it’s associated ventilation boundaries. Should anything leak out of primary containment it would be monitored via Reactor Building ventilation prior to release from the stack or isolated from release upon detection.
Also best I can tell, this plant does not have RCIC, it has an isolation condenser similar to the one I am familiar with. It likely only had dedicated HPCI, LPCI and Core Spray Systems. Auto Depressurization System (ADS) via SRVs to permit LPCI and Core Spray injection.
It is indeterminate if all the ECCS systems failed except ADS due to the Station Blackout caused by Emergency Diesels failing.
ADS is the system that would have required batteries to allow cycling of SRVs to lower vessel pressure. Battery capacity is typically 4 hours to support ADS and Emergency Diesel Starts.
All I have read in print was vessel makeup was by injecting fire water post Station Blackout.
I still ask for a link that states the primary containment, essentially the Drywell and/or the Torus for a Mark 1 containment failed.
With regards to venting from the torus with failed fuel, you have to over ride the ventilation isolation interlocks for abnormal radiation levels. But venting to lower pressure protects the contaiment from failing and releasing forever. Best I can tell that is what they were doing, which is text book.
@em1ss: I was not trying to assert that the primary containment failed, but that the secondary containmnet failed (I idiotically referred to the secondary containment as a drywell, which, I know refers to the primary containment) and this, due to the design of the mark I BWR with the torus being outside of the drywell, could have damaged the torus, resulting in leakage from the primary containment ( primary containment -> damaged torus -> leak). I am just speculating that the torus is damaged, but the japanese gov seems not willing to confirm or deny that even the primary containmnet is intact, all they are willing to to say is that the RPV is still intact. sorry about the confusion
The question, ultimately, is the torus intact? And is rx pressure low enough to allow LPCI activation (they now have offsite power via external diesels)
Barry, correct classificiation according to the INES scale is not the point.
The point is that if you evacuate 40,000 people from a 10km radius that is correctly perceived to mean that a serious accident HAS happened and that the authorities believe there is a credible risk that something much worse COULD happen.
If no significant numbers of people had to be evacuated the “usual suspects” would of course still make the usual noise with the usual effect.
But because 40,000 people DID have to be evacuated, the repercussions ARE much more serious. (I am deliberately not saying WILL or MIGHT be but ARE).
People don’t want industries that require disruptive evacuations. They WILL demand still greater regulaton and safety. So any strategy of getting LCOE for nuclear below coal by easing regulation and “excessive” safety just got considerably less plausible.
Granted immediate tasks countering alarmist rumours are more pressing. But you will need to reflect on this later.
Even if everyone hear unanimously agrees its INES level 4 or less serious and even if that becomes the official conclusion, the consequences of having to evacuate 40,000 people ARE that achieving an immediate rollout becomes that much harder and proposing massive R&D that includes nuclear as well as other technologies and provides for nuclear research and training institutes and plants becomes that much more attractive an alternative strategy.
James link that they have the portable diesels connected and to what?
I am not sure they brought anything bigger than to keep the batteries charged yet. That would be a small towable dc diesel like some US plants have purchased for Station Blackout to extend ADS availability. A diesel to run ECCS type pumps would be quite large.
Correction, small capacity AC portable diesel to power the battery chargers.
I can give you the TEPCO press release which argues that external AC power is availble.
http://www.tepco.co.jp/en/press/corp-com/release/11031221-e.html
Multiple news reports have said that they brought in some sort of emergency power generation, presumably diesels. Your right about the power requirement regarding ECCS (quite significant) and also wouldn’t it be a little complicated to connect the external power up to the emergency power trains? They seem to be cooling mainly thorugh the isolation condenser and Make-up Water Condensate System, which is relatively low volume right? All of this seems to indicate they still have a high rx pressure…
I suspect the evacuation may be tied to the failed Fuel Cladding, Reactor Building (Secondary Containment), Spent Fuel Pool exposure to the atmosphere, and/or dual units struggling with cooling due to Emergency Diesel failures. There is always some judgement call with Protective Action Recommendations (evacuation distance and shelter distance), one you can’t win either way after the fact.
The question is, if they have external power availbe, why didnt they run the reactor building vent fans as well as vent the reactor building to the stack to reduce H2 concentration (I dont think Mark I have H2 ingnitors, only Mark III do) before they blew the whole building, as well as run LPCI and core spray.
News releases are usually colored a bit as we all know. One plant I know has little hand carried honda ac generators and inverters to keep the SRVs available by damage control procedures. Along with a slightly larger towable to charge the batteries and air start systems to allow emergency diesel restarts.
They are also having problems with the ADS considering the suppression pool temp is above 100C.
BBC reports an explosion.
NHK:
Explosion heard at quake-hit reactor
The Nuclear and Industrial Safety Agency is trying to confirm a report that an explosion occurred at a nuclear power station in quake-hit Fukushima Prefecture.
The agency said on Saturday that a person at the Fukushima Number One nuclear station reported that an explosion was heard and smoke was seen near one of the reactors at around 4PM.
The power station operator Tokyo Electric Power Company told the agency that 4 people were injured.
Video of the reactor in question shows the outer wall of the building that houses the reactor has disappeared.
Prefectural authorities say the power company informed them that the ceiling of the building collapsed after an explosion.
http://www3.nhk.or.jp/daily/english/12_50.html
James Krellenstein,
The TEPCO press release you linked was for Fukushima Daini. The reactor in question is at Fukushima Daiichi. Nothing on the TEPCO website, as far as I can see, indicates that external power is available at Daiichi.
I mean it has been over a day, you don’t think they got the diesels up and running? What about the condensate make up system, doesnt that require safety AC? Second of all, if they are truly in a station blackout, and already have core damage, what is the plan to get the core covered?
@Scott
Your right… I guess they are in a true station blackout, that is not good….
I don’t think they had power to run the ventilation fans. Hence why I question the reports about diesels brought in.
They would likely need a 3-5 MW diesel to support ECCS pump loads and ventilation, just one train of ECCS too typically. We’re talking a big diesel and big cable tie ins via the ECCS off site tranformer sources likely. Railroad car sized. The rail system is a mess now too.
Too soon to be available even now let alone prior to the explosion by my judgement. Better chance of restoring off site power, but don’t know the scope of that damage either.
“officials say the explosion was not a nuclear explosion” -NPR. John Hamilton being interviewed: “very strong blast … looked like the building that houses the reactor … as workers were trying to add water … that can cause hydrogen …”
“nothing they did seemed to be enough to keep the core under control …. extended the evacuation …. out to 12 miles away”
“the containment structure … did not go in the explosion and the radioactive material is inside that…. they are going to flood the core with seawater … they are also going to put in boric acid ….”
“Situation of power source to recover water injection function at the Station.
-Cable from electric power generating cars are under connecting work (as of 11:00, March 12).
”
http://www.nisa.meti.go.jp/english/files/en20110312-4.pdf
Not sure what happened after. That was before the explosion.
The core was being kept covered by fire water by last report I read. Standard text book severe accident response. Which could be a diesel fire pump. Diesel pumps are easier to aquire than the size Diesel Generator required to use installed ECCS or non ECCS pumps.
Your right, I guess we can conclude that the plant is in a total station blackout, and as Scott rightly, pointed out, TEPCO has said nothing about external power being available to Fukushima Daichi. THis is way beyond DBA.
I guess rx pressure is low enough to allow the core to be covered by fire pumps? where did you read about the fire pumps?
Just asking, does everyone here understand that Hydrogen is a normal byproduct of fission in a BWR, even through decay heat…. It slows with the reactor shutdown, but doesn’t go away for awhile. Adding water doesn’t produce hydrogen alone….the fission in the core does.
I always read news reports with some skepticism. For example, “It wasn’t a fire. It was a spontaneous exothermic reaction resulting in heat and smoke.” That was a classic news release I saw once.
Yes I understand that H2 production is normal through radiolysis
That was early this morning, the fire water makeup. They were switching straight to Sea Water later this morning, which would be the fire back up source I would presume. Meaning they likely used their available clean fire source or would and want to keep some available in case another fire breaks out on site.
The Hydrogen comment was meant to say the explaination for the explosion is still suspect…. Adding water created hydrogen…..
Is the core covered?
But how did the H2 leak out of the system? through the SRVs?
and if the H2 concentration was high enough in the secondary containment to explode, isn’t it likely that the h2 concentration in the primary containment is also really high
Old steel with 40 years of neutron embrittlement has to be a current concern, the hope would be I think that the temperature change is slow enough that there’s not a shock that fractures anything important. The reason for adding borate would have to be to anticipate a possible collapse of the fuel to the bottom of the structure producing a hot spot that would be less well flooded with water, the ‘China Syndrome’ configuration.
Above are my amateur guesses both.
Much appreciate the people who’ve posted with real experience and knowledge and pointers and pictures.
I read in link above that radiation is 1000 microsieverts/hour at one of the plants.
that’s 100 mrem/hour at the plant site.
doesn’t sound too good.
what happened to stories about reduced radiation? B.S? wrong?
And is isn’t a pretty good sign if there is signifcant H2 production while the rx is scrammed, that there is a steam interaction with the fuel rods, i.e. a zirconium catalyzed radiolysis like what we saw in TMI?
Based on reports of Radiation releases and Rad Levels… I’d bet on yes. But that could change quick. As time passes they gain time to respond to failures, decay heat lowers. Until now they have been floating at the boiling point in the core it seems.
If they get sea water injection to the core that will cool them down and establish a time to boil should injection be lost. Pump water in, relieve it to the Torus until containment flood up is achieved. This will cool the core and the Torus.
This unit despite indicated minor fuel damage is likely off line forever. Just based on age and the Reactor Building damage alone.
@ Hank Robert:
Even if there was a core melt, and there was a “hot spot”, there we be no worries about fission, because in a LWR, water is required as a neutron moderator and with no water, no fission!
Yeah the rx is definetly gone. Once they pump seawater in, it is toast.
I, to be honest, am skeptical that the reactor pressure is low enough yet to inject seawater.
They had only decay heat removal via SRVs available to the Torus, until the Torus became to hot to suppress the steam. All that Hydrogen produced is in containment and the Torus. The MSIVs were closed.
They had to vent the Torus to prevent over pressurization and primary containment failure. Yes Zirc Water could contribute, but the gaseous releases while venting don’t support that amount of clad damage yet.
Stepping back, the cautionary lesson here ought to be associated with the warnings about (1) sea level rise over the next 50-100 years raising the baseline against which a storm surge/tsunami will rise, worst case; and (2) a big solar flare taking down the electrical grid across a continent or worldwide, again at least the worst case from the 1800s telegraph era (do we have paleo evidence for anything worse than that?)
It sounds like these two Japanese plants were prepared for one or two plants at a time to need emergency cooling, with quick return of external AC power.
We have a small example of what would happen if the whole grid went down across a larger area because of a major flare (where it might take a year or more to replace transformers).
Sounds to me like it’s time to recommend collaborative designs to go with (Gen4) fission plants — large solar collector fields, and pumped water, hot salt heat, or compressed air geological power storage; put together in a way that each such design site would have redundant power available while all went well, and _still_ have a large stable power supply onsite for the worst case loss-of-grid accident.
And that whole system needs to be built well, well above the anticipated worst case height of a tsunami on top of a high tide during a storm surge after a century of sea level rise.
Barry, it’s time to throttle the economists and get the public health and safety design people involved in building the next generation of power systems.
Greg, where did you read the 100 mr/hr on site?
So they vented the torus to the secondary containment or through the stack (I thought direct torus vent system vented to the stack)? I would be worried about a possible H2 explosion in the primary containment.
The US grid is in complete neglect with deregulation in some areas and not in others. Stability is the worst I’ve ever seen it and that should be addressed post this event for sure.
I am relying on memory here, but the modification for the Mark 1 Torus direct vent was still via Reactor Building Ventilation as a monitored release.
> water as a moderator
The worry would be a collapse to create a ‘bowl of hot stuff’ at the bottom of the building in an area that’s already flooded with water. Or rather, worst case would be that then breaking through to the water table — the whole plant is on flat ground and is at sea level, the ground under must be saturated with water by now just from the pumping.
Yes, once an area heats up enough to boil, the steam won’t slow neutrons down, so you’d get worst case something that would heat, then cool, then heat — as long as water could get back into the material.
I could be wrong on that, it may have gone right to the stack….
Wikipedia tells me that tepco is reporting a reading of 385.8 microsievarts (38.5 millirem) per hour at the plant gate
http://www3.nhk.or.jp/daily/english/12_51.html
I read it here, the 1000 microsieverts/hour.
gm
It is not really important whether DTVS vents to the rx building or to the stack… the real important issure is if there is a combustible mix of h2 and o2 in the primary containment
http://online.wsj.com/article/SB10001424052748703555404576195700301455480.html?mod=WSJ_hp_LEFTTopStories
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
“authorities are preparing to distribute tablets of non-radioactive potassium-iodide. This is quickly taken up by the body and its presence prevents the take-up of iodine should people be exposed to it.
…
Seawater injection
The injection of seawater into the building started at 8.20pm and this is planned to be followed by addition of boric acid, which is used to inhibit nuclear reactions. However, Tepco reported at 10.15pm that a new tsunami warning has caused this to be suspended temporarily….”
——
CDC on potassium iodide:
http://www.bt.cdc.gov/radiation/ki.asp
Actually James it is important. If it went to the stack via Reactor Building Ventilation it would have been diluted had the fans been running. Ie. non explosive concentration, despite the high concentration being vented.
but we know that was not the case, right? cause we saw a hydrogen explosion in the secondary containment, right?
i meant to say, it is not important as of now…
Folks the 1,015 microsievert was a reading taken right after the explosion around 3:30 pm in Japan.
Consequent measurements taken after showed a significant drops of radiation level. Also that the pressure within the Canister was deceasing on it’s own as well.
If I had to take a guess on the cause of the explosion, I’ll take a leakage of the hydrogen turbine coolant (used to cool the generator, same as with any coal plant) as my guess – not hydrogen from within the reactor coolant.
Now that I think about it and reflect on the Company media posts. What’s between the Containment and the atmosphere? The Reactor Building walls. The media spin doctors could call that the space between primary containment and concrete walls (Rx Building walls ie secondary containment).
Thanks Nikkei.
are there more links, updated, that corroborate the reduction? I have seen some, but not updated.
if it was the hydrogen turbine coolant, we would have seen the explosion in the turbine building, not in the rx building.
This is not good news.
http://www3.nhk.or.jp/daily/english/12_57.html
“… Fukushima Prefecture says 3 patients at a hospital near the damaged nuclear power plant have been exposed to radiation.
The hospital is located in Futaba Town about 3 kilometers north of the Fukushima Number One Nuclear Power Plant. It is within the designated evacuation area of 10 kilometers around the quake-damaged plant.
The 3 were chosen randomly for radiation testing from 90 patients and staff who were waiting for airlift by helicopter at a nearby high school on Saturday afternoon. The prefectural government says the 3 need decontamination to remove the radioactivity. They have not shown any reaction or physical symptoms of the radioactivity yet.
Sunday, March 13, 2011 00:58 +0900 (JST)”
Luke that would have destroyed the turbine building, which appears to be intact. Not blown the walls off the Reactor Building. I was hoping that too early on until the pictures were clearer.
Reactor Building Ventilation is part of secondary containment….
I know that, so are you hypothesizing that the explosion occured due to the lack of fans in the 2nd containment (which prevented the h2 from being diluted) during the direct torus vent?
No explanation from Tepco, just a description:
http://www.tepco.co.jp/en/press/corp-com/release/11031225-e.html
“Press Release (Mar 12,2011)
White smoke around the Fukushima Daiichi Nuclear Power Station Unit 1
Today at approximately 3:36PM, a big quake occurred and there was a big sound around the Unit 1 and white smoke….
We are presently checking on the site situation of each plant and effect of discharged radioactive materials.”
just FYI: containment pressure is at about 840 kPa.
Exactly, If I remember the modification vent path correctly….
If that was so… why would the explosion not travel back into the primary containment?
maybe it did and the containment withstood it?
Or maybe the area or part of the building ventilation that blew was actually isolated from the main vent path, but leaking slightly. That would explain why the torus vent path is reported as still in tact.
Any word out there on the spent fuel pool?
Nothing on the Spent Fuel Pool that I can find anyways…
So i looked up the NRC doc describing the DTVS, it is ADAMS accesion no. ml031140220. The DTVS directly vents to the stack via an 8″ pipe that bypasses the standby gas treatment system
Gregory Meyerson
I got that news directly from a press conference off of NHK tv.
Yukio Edano said they were taking regular measurements of radioactivity starting at the time of the explosion. I’ve got an earlier post describing the the amounts and at what time. He also stated the the pressure inside the reactor was decreasing as well. This is also where I heard the use of sea water.
Here’s a link to the press conference that I saw which has a basic description in English:
http://www3.nhk.or.jp/daily/english/12_56.html
[…] daños en el edificio contenedor interior durante la explosión. Otro repaso a los hechos: Japanese nuclear reactors and the 11 March 2011 earthquake en Brave New […]
Thanks James, I was wrong then maybe there is some truth to the pumping cause they reported.
no problem em1ss, i wish you were right though, because this is now even weirder…
Had to be some voided system they were using to inject I guess…
May I ask some more stupid questions (in relatively layman terms)?
Although the fission of uranium has stopped, thermal energy from the decay of the materials in the fuel rods must be removed by circulating coolant water through the reactor. The presence of cesium and iodine compounds in the steam released from the containment building shows that the fuel rods have failed (either split or melted) and any coolant water sent into the reactor will absorb radioactive material.
1. Is it true that the coolant water circulation loop at this plant has only one eventual heat sink, the circulation of ocean water to cool the coolant water? From the absence of cooling towers, I am assuming that this is the case.
2. Is it true that the presence of radioactive materials in the steam vented from the containment building means that both the fuel rods have failed contaminating the coolant water system, AND that the earthquake has created leaks in the coolant water circulation system, such that radioactive material and hydrogen accumulated in the containment building, and this accounts for vent of radioactive materials?
3. The explosion seems to have been caused by hydrogen buildup in the containment building and systems. If the coolant water circulation is continued, as it must to remove decay heat from the reactor, does this mean there will continue to be leakage of the radioactive coolant water?
4. The presence of significant radiation at the plant perimeter, and the fact that three people randomly selected from an evacuation zone showed high levels of radioactive exposure, means that radioactive material is dispersing through the environment around the plant. If the coolant water circulation in the plant continues, as it must to remove decay heat, won’t the leakage of radioactive material continue, give the failure of the containment systems?
5. Does the fact that the operators are now planning to flood the reactor with seawater, mean that seawater will be circulated through the reactor? But any seawater circulated through the reactor will need to be discharged to effectively remove heat from the reactor?
6. So instead of circulating coolant water and suffering radioactive releases from leaks in the coolant water and containment system, they have elected to circulate large amounts of seawater through the reactor, which will be contaminated with radioactive material and the radioactive seawater will be dumped in the ocean? So instead of vent releases to the air, authorities are electing to try and minimize vent releases by circulating seawater and contaminating the ocean instead?
7. Can the seawater circulated in this manner be contaminated with plutonium?
I would appreciate any answers from the nuclear experts on this thread.
I have family and friends in Japan and am finding it very frustrating to find news and information from credible sources in English. I came across this site and it has helped enormously – THANK YOU! I have seen so many conflicting reports on TV and on the internet – from meltdown is imminent to risk is low….what do you think of “expert” interviews like this
I’m assuming that they’re talking about something like spraying seawater into the containment, to cool it, bring pressure down, and to help scrub out any gaseous radioactive contamination if it’s present.
I don’t think they would actually put seawater into the reactor coolant system – that’s nuts. It seems completely pointless and unnecessary, and it will basically completely write off the reactor.
Ok, it appears from this account, that they aren’t circulating seawater through the reactor, but using seawater to deliver boric acid into the reactor containment, however the wording in this statement seems vague.
Sea water used for cooling down the reactor
The Tokyo Electric Power Company is using sea water as an emergency coolant in its quake-damaged reactor at Fukushima Number One Power Plant.
The massive earthquake on Friday caused a breakdown of cooling systems that could cause temperatures in the reactor to rise to uncontrollable levels.
Chief Cabinet Secretary Yukio Edano disclosed on Saturday that the company is pouring sea water into the containment vessel of the reactor. Sea water is readily available as the plant is close to the sea.
Edano said the company is mixing boric acid with the water to help absorb neutrons to slow nuclear fission.
Edano added that government’s Nuclear and Industrial Safety Agency has endorsed the procedure.
Self-Defense Force troops, who are actually in charge of the cooling process, are using pump trucks and other methods to inject the sea water. They say the work started on Saturday evening will be completed on early Sunday.
> seawater to deliver boric acid into the reactor
> containment
Guessing — would the logic here be to surround the actual reactor vessel, to fill the concrete building shell with boric acid solution? So if the reactor vessel steel doesn’t shatter, it’d cool down, and if the steel does shatter and the fuel structure collapses into the bottom of the building, it’d be falling into the boric acid solution.
What’s the possibility they are flooding it in preparation for the core breaching the RPV?
http://e.nikkei.com/e/fr/tnks/Nni20110312D12JFF03.htm
I have a question about containment domes.
Was the thing that gave way at the daichhi nuclear plant a containment dome or is it as barry suggested that the CD is internal?
second, if the answer is the former, is this the sort of dome that jets cannot penetrate, as in the you tube videos?
Look back in the thread here for diagrams of the structure. This is a relatively small steel bottle (containment) inside a concrete structure (building). There is no “dome” — this is a 40-year-old design.
All the info is earlier in the thread.
______
On the fuel rod damage, here is a link with a translation giving the original Japanese source:
http://mrzine.monthlyreview.org/2011/fukushima120311.html
http://www.nisa.meti.go.jp/english/index.html
scott’s link indicates the reactor began melting down.
if the meltdown caused the explosion, and containment was not breached, how would this happen exactly?
Hydrogen from zirconium oxidation at high temperatures vents to outer building; explodes. They announced prior to explosion they’d be doing some venting to reduce pressure. That’s my guess.
thanks hank.
gm
Tepco seems way behind, their latest press release still says:
“Indication from monitoring posts installed at the site boundary did not show any difference from ordinary level. No radiation impact to the external environment has been confirmed. We will continue to monitor in detail the possibility of radioactive material being discharged from exhaust stack or discharge canal.”
Last night I recall a problem with opening vents — one vent was too radioactive to get a worker to it. Has that been updated anywhere? I wondered if this is why they had hydrogen building up-perhaps they weren’t able to vent enough of it out fast enough? But I haven’t seen mention of that problem at all today.
“According to technical documents translated by Aileen Mioko Smith of Green Action in Japan, if the coolant level dropped to the top of the active fuel rods in the core, damage to the core would begin about 40 minutes later, and damage to the reactor vessel would occur 90 minutes after that.”
http://mrzine.monthlyreview.org/2011/ucs110311.html
It seems that this is a classical example of cascading failure.
The nuclear engineers on this site are quick to point out the ‘strengths’ of each defensive layer. However, the reality of catastrophic situations is that they tend to reveal the ‘weakness’ of each layer.
‘Defense in depth’ is predicated on the idea that the probability of each layer being simultaneously or near simultaneously defeated is improbable. However, as most seiges of castles showed, and most cascading failure events as well, there is a relatively high probability that a chaotic, uncontrolled situation will defeat each layer in turn – given enough time.
The nuclear engineers will now jump on the time element and say that the reactor going cold means ‘time is on the nuclear operators side’. However, that logic only applies for a near steady state scenario.
Disaster is simply a combination of factors waiting to align. Over time, a chaotic system will test the system repeatedly – the permutations multiply and eventually nature finds the key to complete failure. Simply put, all man-made systems are eventually destroyed by nature because chaos is kinda hard to model against.
To relate how mistaken the nuclear engineers are, it’s obvious that this earthquake was not a ’10,000′ year event – it just makes the top 10 list of the last century. The reactors structure may have been able to withstand the forces of an even larger earthquake, but the reactor ‘system’ couldn’t withstand the external failures caused by the earthquake.
If everything went ‘according to plan’, this reactor should still be operating. Now the question is: how good are the plans for dealing with the failure of the nuclear operations plan?
By the way, I like nuclear more than coal…but renewables more than all.
according to the nisa documents linked by hank, radiation release increased in a 5-6 hour period from .7 to 5.1 at main gate and .7 to 2.7 (in microsieverts) at observation post.
that’s a lot lower than 1015.
I don’t know what these numbers relation is supposed to be.
P.S. A chaotic system may sometimes give you the result you hope for…but that’s not exactly a good way to ‘plan’.
It’s not clear how many plants are in trouble now. Is there a map showing Fukushima 1 and 2? Separate evacuation zones declared? I’m seeing only fragmentary stuff in translation:
Evacuation area around Fukushima No.2 expanded
http://www.nhk.or.jp/daily/english/politics.xml
NHK WORLD English
… The prefectural government of Fukushima has … expanded the evacuation area around Fukushima Number 1 Power Station from … kilometer radius around the Number 2 Power Station. …
http://www.nhk.or.jp/daily/english/society.html
http://uvdiv.blogspot.com/2011/03/where-is-spent-fuel-now.html
Where is the spent fuel now?
The spent fuel pool is on the top floor of the reactor building (assuming this is the same layout):
GE Mark I BWR containment [Magdi Ragheb, U. Illinois at Urbana-Champaign]
Luke – Where we are today, I wouldn’t put any money on a restart of Fukushima Daiichi reactor 1. If filling the reactor vessel with seawater is needed to stabilize the decay heat, that’s what they should do.
http://www.newscientist.com/blogs/shortsharpscience/2011/03/massive-explosion-rips-through.html
Current latest NISA release with the ‘microsieverts’ measurements is:
http://www.nisa.meti.go.jp/english/files/en20110312-4.pdf
—-
From 04:00, March 12 by the measurement of radioactive materials in the surrounding area of the power station using monitoring cars. (As of 09:40, March12)
It was confirmed that radioactivity was increased compared to the one at 04:00, March 12.
MP6 (near the main gate) 0.07microSv/h ->5.1 micro Sv/h (04:00, March12->09:10, March 12)
MP8 (observation platform) 0.07microSv/h ->2.9 micro Sv/h (04:00, March 12->09:40, March 12)
NOTE where the decimal points are; I’m _guessing_ that 0.07microSv/h is the baseline (anyone know?)
OK, I understand that given the reactor’s age they will probably write it off.
“Because the plant went into operation in 1971 and is due for decommissioning, the decision was taken by Tepco to flood it with seawater containing boric acid to kill the nuclear reaction.”
This boric acid business doesn’t make any sense. The control rods are all in, the reactor is fully subcritical. Why are we talking about emergency addition of boric acid? There shouldn’t be any kind of criticality issue at all, from my understanding.
@Hank Roberts
The English news releases are going to be slow to update. Tokyo Electric, the Prime Minister, and Chief Cabinet Secretary Yukio Edano have all had numerous press conferences on national tv in Japan.
The info is out there but there’s only fragments of what they said in English. Kind of sad, you think CNN would have someone watching NHK to translate what was said.
Luke, you can get a whole lot of heat out of the fuel rods for four days or so after a proper shutdown. If the cooling water system has failed (did the ECCS ever get used, anyone know??) then the fuel rod assembly is going to continue to get worse. If the control rods fall out — if the structure falls apart — the fuel rods can end up in a random pile along with the rest of the structure. That could put hot stuff together in a way that lets the heat increase enough to melt the steel. So they want the boric acid solution all around to catch the pieces that could fall through the bottom of the steel containment.
That’s an amateur guess only. Wait for someone who knows better for a better answer.
I’m still not clear if the boric acid is going into the concrete building _around_ the steel bottle, or if they’re actually pumping it into the bottle so it floods the reactor core. Anyone got a pointer to better info? Those are very different tactics.
NYT:
“The blast, apparently caused by a sharp buildup of pressure or of hydrogen when the reactor’s cooling system failed after the quake, destroyed the concrete structure surrounding the reactor but did not collapse the critical steel container inside, they said. They said that raised the chances they could continue cooling the core, and prevent the release of large amounts of radioactive material and avoid a full core meltdown at the plant.
…
Tokyo Electric Power … plans to fill the reactor with seawater to cool it down and reduce pressure. The process would take five to 10 hours, Mr. Edano said, expressing confidence that the operation could “prevent criticality.”
The company also said its workers also added boric acid to the containment vessel on Saturday night to poison the nuclear chain reaction.
——-
http://www.nytimes.com/2011/03/13/world/asia/13nuclear.html?_r=1&hp=&adxnnl=1&adxnnlx=1299960040-FXxZ1eYct1HY/+40l2dlLg
Oops. Here’s another radiation figure — this in “rem”
1 rem=0.01 Sv
“Fukushima – Home Page Promo – March 2011UPDATE AS OF 12:30 P.M. EST, SATURDAY, MARCH 12:
… Tokyo Electric Power Co., reported that radiation levels next to the Unit 1 machine building had increased from 0.007 rem per hour to .67 rem per hour.”
This helps explain — the boric acid apparently is being pumped both into the steel bottle-reactor core and also around it.
http://www.npr.org/blogs/thetwo-way/2011/03/12/134486565/at-crippled-japanese-nuclear-plant-last-ditch-effort-to-prevent-meltdown?ft=1&f=1001
Linda Wertheimer speaks with NPR’s Jon Hamilton
“On Weekend Edition, Jon told host Linda Wertheimer that the plan to flood the core with seawater and boric acid may be unprecedented and will effectively destroy the power plant. If the plan fails and the core does meltdown, Jon said the only thing left to do will be to “seal it up with concrete. You sort of entomb it.”
And it would be the containment structure that would be entombed — hopefully with any radioactive material still inside. In theory, NPR’s Science Desk tells us, if there was a meltdown that destroyed the steel and ceramic around the fuel rods the containment structure would still be able to prevent any material from being released into the environment…. At Three Mile Island in Pennsylvania, the containment structure prevented a disaster when part of the core melted during a 1979 accident.
The situation likely won’t be resolved quickly. According to Japan’s Kyodo News:
“The top government spokesman said Tokyo Electric Power has begun operations to fill the reactor with sea water and pour in boric acid to prevent an occurrence of criticality, noting it may take several hours to inject water into the reactor. In addition, it will take about 10 days to fill the container with sea water, he said.”
Discussion about what happens when a core starts to melt make comparisons to Three Mile Island — which was a different design, with a large containment building — domed top — around the whole reactor bottle and associated equipment.
“Because adequate cooling was not available, the nuclear fuel overheated to the point at which the zirconium cladding (the long metal tubes which hold the nuclear fuel pellets) ruptured and the fuel pellets began to melt. It was later found that about one-half of the core melted during the early stages of the accident. Although the TMI-2 plant suffered a severe core meltdown, the most dangerous kind of nuclear power accident, it did not produce the worst-case consequences that reactor experts had long feared. In a worst-case accident, the melting of nuclear fuel would lead to a breach of the walls of the containment building and release massive quantities of radiation to the environment. But this did not occur as a result of the three Mile Island accident.”
It may help to compare the TMI building to the pictures above in this thread of the BWR-3 (Fukushima-1 is a BWR-3 according to the references given earlier).
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html#tmiview
This may be reassuring. While the diagrams above show a “spent fuel pool” located immediately next to the top of the reactor bottle — that’s not longterm storage, it’s a handling point for refueling operations.
Here is a description from late 2010 of the site and an assessment of its spent fuel storage — shows the building (though not where the building is on the site). Spent fuel is in dry casks, sealed and air-cooled. I don’t know what if anything would have been in the pool at the top of the reactor building and haven’t seen any pictures since the explosion to know what that situation is. But most of the spent fuel should have been well away from that. What the tsunami did to the storage is an open question though. How much water did hit the site?
——
Integrity Inspection of Dry Storage Casks and Spent Fuels… Storage Status of Spent Fuel at Fukushima-Daiichi NPS. ➢ Approx. 700 spent fuel assemblies are generated every year. ⇨Stored in spent fuel pools / dry …
http://criepi.denken.or.jp/result/event/seminar/2010/issf/…/6-1_powerpoint.pdf
This may be the same document:
http://www-ns.iaea.org/downloads/rw/conferences/spentfuel2010/sessions/session-ten-b/session-10b-japan-1.ppt.
Oh lord, the sea water is a last ditch effort? What is it about American news outlets that need to make everything overly dramatic.
> last ditch
> last ditch
Seemed appropriate to me.
“Last ditch” is an idiom in US English, often used describing football for example. It comes from trench warfare-World War 1 or even earlier: the last line holding back the enemy advance, well inside the perimeter that was thought defensible.
They’re using “last ditch” for an action beyond the planned “layered defense in depth” steps. Those were reversible and could have recovered the plant in condition it could be salvaged. Once the building exploded, that was pretty much not going to happen.
(One of those steps was the Emergency Core Cooling System-did that even get tried before the building explosion? I would guess from the video, which showed big chunks being thrown a long way through the air, that they may have lost the pipes and valves outside the steel bottle then.)
Can you suggest another step after filling the plant with sea water and boron? That’s been reported as not something that was one of their layered plan steps.
If that works, the bottle stays intact, the whole area cools off below boiling, the radiation decays away, they pump the contaminated water through filters and demineralizers to concentrate the waste, and they eventually clean it up.
If that fails — if they don’t get the core cold and it ends up breaching the bottle — what’s to do except entombment of the whole site?
Damn.
Sat Mar 12, 2011 4:17pm EST
(Reuters) – A quake-hit Japanese nuclear plant reeling from an explosion at one of its reactors has also lost its emergency cooling system at another reactor, Japan’s nuclear power safety agency said on Sunday.
The emergency cooling system is no longer functioning at the No.3 reactor at Tokyo Electric Power Co’s Fukushima Daiichi nuclear power facility, requiring the facility to urgently secure a means to supply water to the reactor, an official of the Japan Nuclear and Industrial Safety Agency told a news conference.
Another idiom:
http://abcnews.go.com/International/japan-fukushima-nuclear-power-plant-explosion-workers-injured-radiation/story?id=13120888
“Flooding the containment vessel with sea water mixed with boron instead of fresh water is an unusual measure, according to Robert Alvarez, a senior scholar at the Institute for Policy Studies, who described it as a “Hail Mary pass” but a necessary step to keep the reactor core covered and the containment vessel cool.”
—————
http://www3.nhk.or.jp/daily/english/12_34.html
updated at 18:16 UTC, Mar. 12
A nuclear emergency has been declared at Fukushima No.2 nuclear plant …. This follows Friday’s emergency declaration for Fukushima No.1 nuclear plant ….
… the pressure control system is not functioning at the plant’s 3 reactors….
Map showing Fukushima No. 1 site, No. 2 site, and radius of evacuation orders for both. The larger radius encompasses the smaller one — complete overlap.
http://www3.nhk.or.jp/daily/english/update/images/12_54_v_s.jpg
http://www.japantoday.com/category/national/view/explosion-heard-at-fukushima-nuclear-plant-4-injured-tepco
[…] Ten of Japan’s 55 nuclear reactors have been shut down due to the tragic 11 March earthquake. There is no serious health or safety risk from any of these plants. However, if your information is coming from the daily media, especially television, it may appear that a “Chernobyl incident” is underway in Japan. For accurate, timely information and discussion I recommend Prof. Barry Brook’s BraveNewClimate website. […]
Firstly, far more megawatts of renewable power could be generated per pound/dollar spent on nuclear, Consider, for example, the new epr reactor, Olkiluoto 3, in Finland. Already costing over 6 billion euros, it is set to provide 1600 Mwatts of electricity.Compare that with about 3.5 million for a 2 Mwatt wind turbine. 1600 Mwatts would then cost about 3 billion euros,and even before you take into account the economies of scale that result from upscaling from a single 2Mwatt turbine. That’s also before you factor in the cost of decommissioning and waste management.
We urgenrly need to stop wasting our finite capital on fission energy.
Secondly, although nuclear power is less emissive than fossil fuels, it still requires huge fossil fueled machinery to extract it, and then further energy is required to transport it to where it is needed. As a means of combatting carbon emissions, it’s only the second worst of many evils. Nuclear power stations themselves too require a huge amount of resources to build and operate.
Thirdly, uranium itself is finite. To replace fossil fuels with nuclear would bring forward “peak uranium” to a point in the very near future.
I’ve heard it argued, by James Lovelock and others, that Nuclear power is essential to provide a reliable energy source while a transition to renewable sources takes place, but nuclear power plants take over a decade to plan and construct and activate. We need cuts in emission NOW, not 15 years down the line. Also, see my first point. If the same capacity can be constructed quicker, greener and for a fraction of the cost going for renewables now, what on earth is the point of going nuclear?
hey paul:
You’re new here. Glad you showed up. I think all of your arguments are incorrect but don’t have the energy to go into details. The section at BNC on renewable energy is excellent and you should spend some time reading all the articles, along with much of the response. Everyone of your points is addressed in great detail.
It would be nice if what you said was true; but I don’t think it is.
Meanwhile, I’m feeling depressed. I have spent several years studying the energy/ecology crises as a fairly intelligent non expert.
And even though I think we have to go with gen three and four nuclear, I’m at the moment less than optimistic.
Maybe it’ll look different in the morning.
btw, I thought the point way above thread about Defense in depth not handling multiple problems at once is a good point. Course, with passive safety, we wouldn’t be in this pickle.
///Course, with passive safety, we wouldn’t be in this pickle.////
Yeah, agreed.
Right now I’m hoping we can invent the super-cheap battery to make renewables an option, because I’m losing confidence that we can overcome the ‘nukes aren’t safe’ argument.
Last night the world watched a nuclear housing container building explode. It’s NOT a good look! Unless they can comprehensively show that the core is safe and this is not another Chernobyl, we’re done. Where’s Peter Lang with his “Older, cheaper, Nastier Nukes to save a few bucks!” now when these older cheaper nukes have blown up in his face?
We either need to show that nothing ‘really bad’ happened here, or that the new technologies WILL NOT do this.
And if we can’t… then I don’t have much hope that we’re going to get through global warming and peak oil with our civilisation intact.
Paul
Sure (if you say so)you can build 1600Mwatts of wind power but you fail to mention the capacity factor. What happens when the wind isn’t blowing? You need back-up power, probably gas-fired(fossil fuel) to ensure continuity of supply. How much will that cost?
As to peak uranium, it is a myth when you consider that new IFR reactors can burn nearly 100% of the fuel and also use once through uranium(waste) as a fuel source. – then there is uranium from sea water.
Obviously you need to educate yourself and this blog gives you all the information you need if you are genuinely interested in the facts and not the hyperbole. Read the posts on renewables and nuclear and learn something useful.
Please, guys, don’t refight the big issues in this topic.
This is a topic specifically for Japan earthquake news.
EN
You are overreacting. According to reports it was the building next to the nuclear housing building exploded and the walls of that building collapsed as a result. The containment vessel is untouched. The IAEA have rated the occurence as a Level 4 incident (Barry predicted that several hours ago) which is less than Three Mile Island, which we all know was not a problem.
Quote: “Consider, for example, the new epr reactor, Olkiluoto 3, in Finland. Already costing over 6 billion euros, it is set to provide 1600 Mwatts of electricity.Compare that with about 3.5 million for a 2 Mwatt wind turbine. 1600 Mwatts would then cost about 3 billion euros,and even before you take into account the economies of scale that result from upscaling from a single 2Mwatt turbine. That’s also before you factor in the cost of decommissioning and waste management.”
Sounds good until you understand that 2Mwatts is only 17% of the time whereas the nuclear plants works 93% of the time.
When you starting match the Mwatt output and the capacity factor you have to have thousands of networked windmill across vast regions using thousands of miles of transmission lines that requires more energy input that you get from the life time of the windmill. And you kills birds and endangered bats.
The only “renewables” worth talking about are large hydroelectric (destroyed in earthquake) and geothermal (indirect nuclear). Greenies oppose those along with nukes because they work.
The greens only believe systems that deliver a negative rate of energy return on investment.
“Unless they can comprehensively show that the core is safe and this is not another Chernobyl, we’re done. ”
Either that is propaganda or you’re just caving into it. Coal has killed and polluted and will kill and pollute far, far more than nuclear has and ever will. (see
http://frankwarner.typepad.com/free_frank_warner/2006/01/us_coal_mining_.html). Correct me if I’m wrong, but wind power disrupts the environment and is unreliable, AKA not cost-effective. Solar is ridiculously expensive and requires a lot of water.
One 40 year old reactor melts down thanks to a double natural disaster on one of the most active spots along the “Ring of Fire”, and now “we’re done”? Are we supposed to go back to horse and buggies, or what??
don’t feed the trolls
I think EN has a very serious point, and should be taken seriously. Ms Perps I think you missed his point.
The point I think EN is making is that even though the consequences of this accident are not extreme, the public will not see it that way. Media hysteria and all that.
EN I really agree with your last point. God, if your up there, you may have screwed our last serious hope of saving the planet.
I don’t see the ramifications of this as damaging at all to nuclear power’s prospects. First, it won’t make a jot of difference to the plans of China, India, South Korea etc. Second, a level-headed analysis after the event will underscore the point that even in the most extreme of situations, with a well beyond design basis event, a 40-year old reactor held up to the most trying circumstances nature could throw at it. It will also point to further improvements that can be made to BWR management and emergency response. Finally, it will provide a great conversation starter for talking intelligently to people about nuclear safety. Remember folks, a large-scale future expansion of nuclear power is inevitable in the long run, and vital in the medium-term if we are to move away from our 80% reliance of fossil fuels today. No amount of hype or FUD can change that basic reality.
Hank did you seriously just try to explain to me what last ditch means?
FINALLY: a clear image of the damage to Unit 1 after the explosion:
http://graphics8.nytimes.com/images/2011/03/13/world/13nuclear2/13nuclear2-popup.jpg
http://www.nytimes.com/2011/03/13/world/asia/13nuclear.html?hp
“TOKYO — Japanese officials took the extraordinary step on Saturday of flooding a crippled nuclear reactor with seawater in a last-ditch effort to avoid a nuclear meltdown ….
… The Japanese Nuclear and Industrial safety agency said as many as 160 people may have been exposed to radiation around the plant, and Japanese news media said three workers at the facility were suffering from full-on radiation sickness.
…
… Olli Heinonen, the former chief inspector for the I.A.E.A., and now a visiting scholar at Harvard, said on Saturday…. “Now, every hour they gain in keeping the reactor cooling down is crucial,” he said.
But he was also concerned about the presence of spent nuclear fuel in a pool inside the same reactor building. The pool, too, needs to remain full of water, to suppress gamma radiation and prevent the old fuel from melting. If the spent fuel is also exposed — and so far there are only sketchy reports about the condition of that building — it could also pose a significant risk to the workers trying to prevent a meltdown in the core….”
Well said Barry. I second that!
FINALLY: a clear image of the damage to Unit 1 after the explosion:
Yep. Definately the reactor building, not the turbine building. My previous guess was wrong.
BBC reports say:
#
2318: US nuclear experts warn that pumping sea water to cool a quake-hit Japanese nuclear reactor is an “act of desperation” that may foreshadow a Chernobyl-like disaster, AFP reports. “The situation has become desperate enough that they apparently don’t have the capability to deliver fresh water or plain water to cool the reactor and stabilise it, and now, in an act of desperation, are having to resort to diverting and using sea water,” said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies.
#
2326: The Japanese cabinet secretary, Yukio Edano, has been speaking on state TV. He said the third reactor at the Fukushima No. I plant was in danger but attempts were under way for a controlled release of air.
Hank
“three workers at the facility were suffering from full-on radiation sickness.”
Let’s get a bit of perspective here- over 100 people have been injured /killed in the oil and gas fires. Not forgetting the hundreds/thousands killed by the quake/tsunami. 10,000 missing from one town which has been wiped out.
Click through for details on design of reactors:
http://www.insc.anl.gov/cgi-bin/sql_interface?view=rx_list&country=all&type=all&status=all&plant=fukushima_daiichi
NHK TV Press conference
Reactor 1
Currently pumping in sea water. Radiation levels haven’t risen.
Reactor 3
Currently using back up pump to inject water, and venting out air.
PaulK2
“The situation has become desperate enough that they apparently don’t have the capability to deliver fresh water or plain water to cool the reactor and stabilise it, and now, in an act of desperation, are having to resort to diverting and using sea water,” said Robert Alvarez, WHO WORKS ON NUCLEAR DISARMAMENT at the Institute for Policy Studies.”
Well, given his job and therefore his bias, he would say that wouldn’t he.
“Japan’s nuclear safety agency reported an emergency at a second reactor Sunday in the same complex … Nuclear and Industrial Safety Agency told the Associated Press early Sunday that the cooling system had malfunctioned at Unit 3 of the Fukushima Daiichi nuclear plant. Officials said they were informed of the emergency by Tokyo Electric …”
http://www.latimes.com/news/nationworld/world/la-fgw-japan-quake-reactor-20110313,0,3933329.story
Ms Perps; No, it was the reactor building that had an explosion, but the Mark I BWRs have a crane area superstructure on top of the main concrete building. That area was wrecked; whether and how far the damage extends into the rest of the building is not clear, but that structure has clearly not been destroyed or even reduced significantly. The spent fuel pool for example should be fine, and the characteristics of the damage suggest to me that the explosion was actually in the crane area rather than coming up from deeper in the building.
[…] Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake Please use this Discussion Thread for the situation in Japan with respect to the Miyagiken-Oki earthquake (8.9 […] […]
Barry,
I agree that those countries making evidence-based decisions (China, India, S Korea, …) will continue unabated.
I fear though that the massive negative publicity of this event in Japan will be reinforced in perpetuity by the anti-nuke crowd, thus making nukes of any kind un-touchable, politically, in EU, North America, Aus, etc.
Unfortunately the anti-nuke crowd will do everything they can to taint by association newer designs – Gen IV, MSR, LFTR, etc.. A massive set-back.
Update here:
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
The ‘naked steel frame’ visible in the post-explosion pictures appears to be the framework shown here at the top: http://www.world-nuclear-news.org/uploadedImages/wnn/Images/bwr%20cutaway.jpg
“Later television shots showed a naked steel frame remaining at the top of the reactor building.”
Same image earlier here: http://i.imgur.com/CckjP.jpg — so it’s clearer now that the concrete structure around the reactor is still in place — it’s this metal framework holding thin walls and roof that blew off, leaving the bare grid showing.
That grid held the walls and roof around the space above the top of the reactor bottle — the space around the crane and work area used to move fuel rods, and above the pool used to hold used fuel rods which is to the side of the reactor bottle.
Los Angeles Times
March 12, 2011, 3:52 p.m.
http://www.latimes.com/news/nationworld/world/la-fgw-japan-quake-meltdown-20110312,0,2889362.story
“… a government official told CNN Sunday morning Japan time.
“There is a possibility, we see the possibility of a meltdown,” said Toshihiro Bannai, director of the international affairs office of Japan’s Nuclear and Industrial Safety, in a telephone interview with CNN from the agency’s Tokyo headquarters. “At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility.”
Bannai said engineers have been unable to get close enough to the reactor’s core to know what’s going on, and that he based his conclusion on radioactive cesium and iodine measured in the air near the plant Saturday night….”
Quick note to say hi. I’m new and absolutely grateful for the sort of balanced discussion going on here.
Best
Luke
“Already costing over 6 billion euros, it is set to provide 1600 Mwatts of electricity.Compare that with about 3.5 million for a 2 Mwatt wind turbine. 1600 Mwatts would then cost about 3 billion euros,and even before you take into account the economies of scale that result from upscaling from a single 2Mwatt turbine.”
According to your own numbers Olkiluoto-3 is a steal compared to wind, even though it’s a first-of-a-kind plant in a nation with limited experience.
With an industry typical 80-90% capacity factor the nuclear plant generates 1.3-1.4 GW on average; that’s $4.2-4.8 per watt of average power.
1600 MW of wind turbines with an industry typical 20-30% capacity factor generate 0.3-0.5 GW of average power. That’s $6-9/W of average power, not counting the cost of building powerlines to remote areas that are only used some of the time(due to the abyssmal capacity factor of wind) and not counting the difficulties of integrating a non-dispatchable power source into the grid(storage is keeps being suggested, but what happens in the real world tends to be sucking on a big fat gas pipe courtesy of Russia).
http://www.reuters.com/article/2011/03/12/us-japan-quake-tepco-radiation-idUSTRE72B3PJ20110312
Sat Mar 12, 2011 5:51pm EST
(Reuters) – Tokyo Electric Power Co (9501.T) has begun preparation to release radioactive steam from a second reactor at its quake-struck Fukushima Daiichi nuclear power facility, a spokesman said on Sunday.
The TEPCO spokesman said preparation work for the release began at 7:30 a.m. (5:30 p.m. EST).
An official from Japan’s nuclear safety watchdog said earlier on Sunday that it had received a report from Japan’s largest power producer at 5:10 a.m. that the facility’s No. 3 reactor had completely lost its emergency cooling function.
—-
On the No. 1 plant:
http://www.reuters.com/article/2011/03/12/us-japan-quake-iaea-idUSTRE72B3C520110312
Sat Mar 12, 2011 4:33pm EST
(Reuters) – Japan told the U.N. atomic watchdog there was an initial increase in radioactivity around a quake-hit nuclear plant on Saturday but levels “have been observed to lessen in recent hours,” the Vienna-based agency said.
The International Atomic Energy Agency (IAEA) said it had also been informed by Japanese authorities that Saturday’s explosion at the Fukushima Daiichi plant occurred outside the primary containment vessel, not inside.
“The plant operator, Tokyo Electric Power Company (TEPCO), has confirmed that the integrity of the primary containment vessel remains intact,” it said in a statement that is likely to be seen as positive for efforts to contain the damage.
…
The government insisted radiation levels were low, saying the blast had not affected the reactor core container.
…. Workers pumped sea water into the reactor to cool it.
“As a countermeasure to limit damage to the reactor core, TEPCO proposed that sea water mixed with boron be injected into the primary containment vessel,” the IAEA said.
“This measure was approved by Japan’s Nuclear and Industrial Safety Agency (NISA) and the injection procedure began at 20:20 local Japan time.”
Paul, on 13 March 2011 at 8:53 AM — That’s off topic for this highly focused thread. Take it to Open Thread 9. Thank you.
Not a Nuclear Expert, but knowledgable and will try to answer your questions.
1. Is it true that the coolant water circulation loop at this plant has only one eventual heat sink, the circulation of ocean water to cool the coolant water?
Yes – There is no cooling tower so the normal heat sink is ocean. But there also is some type of pond that is shared on site by layouts I have seen. This pond may just be water storage though for normal emergency injection, discharge dilution or firewater.
2. Is it true that the presence of radioactive materials in the steam vented from the containment building means that both the fuel rods have failed contaminating the coolant water system, AND that the earthquake has created leaks in the coolant water circulation system, such that radioactive material and hydrogen accumulated in the containment building, and this accounts for vent of radioactive materials?
The Cesnium and Iodine detected are normal fission product gases which can’t normally be detected of significance without zirconium fuel cladding damage too some degree (cracks, pinholes etc). Cesnium and Iodine levels can also be used to predict level of fuel failure (actual pellets inside clad). They would be present to some level even without fuel pellet failure and released at some level upon clad leakage. The fuel rods are designed for some normal fission product gas buildup inside the fuel rod cladding over fuel life without overpressurizing the fuel rod.
First of all the in Mark 1 Containment design the Primary Containment consists of a steel lined drywell and the attached steel lined Torus (suppression chamber). The fission product gases (Cesnium and Iodine) and hydrogen are released from the vessel to the containment during opening of reactor Safety Relief Valves (SRVs) to control reactor pressure. The Steam from the SRVs is directed to the Torus (suppression chamber) below water level and suppressed (quenched) for as long as the Torus temperature stayed below boiling. Discharging the steam below water level also scrubs some of the fission product gasses.
Reaching 100 C Torus temperature was significant in that it meant Torus suppression capability was ultimately lost to suppress the steam from the reactor SRVs. This means cooling of the reactor was being lost via this method.
From that point on any reliefs opened would rapidly pressurize the Torus (containment) requiring containment venting to the release stack to lower Torus pressure and prevent Primary Containment failure due to overpressurization.
Primary Containment failure would mean continuous release from Primary Containment to Secondary Containment (the Reactor Building). As we know the Reactor Building is not entact, so there is no secondary containment boundary left.
There is no indication of an actual vessel or primary coolant system leak yet reported. The fact that the reactor was repressurizing in between SRV openings is a good gross indicator of that. Vessel level was only being lost due to steam release via SRVs.
The fission product gas levels measured during release indicate at most only minor fuel pellet damage and some definite fuel clad damage. Remember there is fission product gas buildup inside the fuel rod clad do to normal operation.
3. The explosion seems to have been caused by hydrogen buildup in the containment building and systems. If the coolant water circulation is continued, as it must to remove decay heat from the reactor, does this mean there will continue to be leakage of the radioactive coolant water?
The explosion in the Secondary Contaiment (Reactor Building) was due to Hydrogen. It is unclear how this occurred during attempts to pump water into the vessel as reported.
As explained above, there is no report of or indication of a primary system coolant leak or leak in the reactor vessel pressure boundary.
Once the containment is flooded heat transfer is from the core to the Salt Water and then radiant through the primary containment steel liner to what’s left of the Reactor Building. You can also feed and bleed, add and remove water to increase cooling. But the volume of water once the containment is full should suffice as decay heat declines over time.
They are injecting salt water via containment spray system which will quench any steam in the containment air space during injection, rapidly lowering containment pressure until all the steam is gone.
This minimizes necessary contaiment venting. But some venting will still be required to permit the volume of saltwater being injected to displace the containment air space.
4. The presence of significant radiation at the plant perimeter, and the fact that three people randomly selected from an evacuation zone showed high levels of radioactive exposure, means that radioactive material is dispersing through the environment around the plant. If the coolant water circulation in the plant continues, as it must to remove decay heat, won’t the leakage of radioactive material continue, give the failure of the containment systems?
The only containment failures based on reports are fuel clad leakage and reactor building secondary containment. Only reported releases are fission product gases due to containment venting operations.
The reported radiaton levels are not that high to indicate fuel failure.
Loss of walls in the reactor building would reduce shielding which would increase rad levels external above normal. Flooding the containment will increase shielding via water from the source the reactor core. Water is better than concrete at shielding.
5. Does the fact that the operators are now planning to flood the reactor with seawater, mean that seawater will be circulated through the reactor? But any seawater circulated through the reactor will need to be discharged to effectively remove heat from the reactor?
See the explaination above of why you flood containment for heat removal. Passing through the core would cool the core faster if you kept an SRV open. But this method would also move alot more radioactive particulate contamination from the core into the containment. See above why containment spray is being used to lower containment pressure too.
6. So instead of circulating coolant water and suffering radioactive releases from leaks in the coolant water and containment system, they have elected to circulate large amounts of seawater through the reactor, which will be contaminated with radioactive material and the radioactive seawater will be dumped in the ocean? So instead of vent releases to the air, authorities are electing to try and minimize vent releases by circulating seawater and contaminating the ocean instead?
No coolant is being circulated back to the ocean using the methods as reported.
7. Can the seawater circulated in this manner be contaminated with plutonium?
If there is fuel pellet damage and clad damage there could be some fission product plutonium detectable in the coolant. Plutonium is a fission product of uranium and always present in spent fuel. As already stated no coolant (salt water) is being circulated back to the environment.
I would appreciate any answers from the nuclear experts on this thread.
Just a small correction, the FP gas in question would have been Xenon, which later decayed to Cesium
correct barry, but they usually report the cesium levels….
I am not an expert, just reading, but I think this
> As we know the Reactor Building is not entact,
>so there is no secondary containment boundary left.
is wrong. Look at the pictures e.g. in Barry’s post above at http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/#comment-113954
The primary containment is a steel bottle around the core — the tall cylinder. That sits inside a concrete secondary containment (like a short fat bowling pin shape) that’s cast concrete — part of the building concrete but sealed and capped.
Those are not pressure vessels, not meant to hold in a high pressure (this is a boiling water reactor not a pressurized water reactor). They did have a vent system that would have led vented material through a filter system.
That apparently failed and the gas was apparently vented into the building, maybe because of the problem reported last night of one of two valves being inaccessible because of radiation levels (anyone hear more on that?).
The rest of the building (including the thin top walls and roof that blew off) is not a containment vessel in this design, and not sealed — it was just closed enough to hold in enough hydrogen gas to have an explosion, but that blew up and outward stripping away the walls and roof leaving the steel frame exposed.
Both of those as far as we know are intact and being flooded now with sea water and borate. Both of those would have been protected from building up too much pressure inside, by releasing steam/air pressure and hydrogen/oxygen gas by opening valves.
I haven’t seen mention of circulating the sea water/boron solution, just pumping it in (taking up to ten days to fill the outside containment). It will take maybe three or four days for the fuel rods to cool down to where there’s less urgency. My guess — just a guess — is the water/boron is intended to be left in place and topped up for a while rather than circulated — with some boiling away, and some release of steam and radiation from the vents.
If there were a working cooling pump system and a working cooling pond as a way of cooling water on the loop pumped through the reactor, they’d be using that and removing heat that way — and that’s not happening.
They are not out of the woods and home yet with this unit, but following the industry established severe accident procedures seems to be working. Effectively protecting the public. This event is way beyond design basis as previosly discussed.
The real concern now is the spent fuel pool which is likely exposed due to the Reactor building wall failures.
The actual spent fuel pool walls are typically steel lined and significantly greater thickness concrete than the external building walls so structurally it is likely ok. The reactor building typically has blow out panels for a steam leak. Failure of actual walls indicates the magnitude of the hydrogen explosion beyond the analyzed pressurization from a steam leak.
As long as they can maintain level in the pool no increase in rad levels should occur. If they lose level though, rad levels will rise dramatically on site and at the site boundary. Keep an eye out for significant rad level changes or actual reports of spent fuel pool status.
Hank, the primary containment in a Mark 1 design is the torus and drywell. Secondary containment is the reactor building and it’s ventilation systems. Read the whole thread this has been previously established.
As far as normal ECCS pumping methods, they are in a station blackout and all electrical ECCS systems except for ADS (using SRVs) are unavailable.
So how does hydrogen from the Zr+ water get out of the reactor vessel and theru secondary containment to blow up between the secondary and skin of the building …?
Hank also regarding spent fuel. It is normally first removed from the vessel and stored in the spent fuel pool for several years of decay. Then it is loaded into casks and placed into dry fuel storage vaults on a pad.
Using seawater is not a “hail mary pass”, to use the American football term, but it certainly is the absolutely last choice.
Nimitz-class A4W reactors have that capability, for use IF water cannot be circulated through the loop(s) and heat removed through the steam generators AND reserve feedwater has run out AND potable water is running out AND the core still needs to be covered, THEN blanking plates can be removed AND large couplings installed AND valves opened to allow firemain water (seawater) to flow through the Rx and into the RX compartment.
Afterwards, you remove the fuel and then replace everything that was touched by seawater, because the corrosion issues both inside and outside the primary piping. It would be much less expensive to simply take the whole mess and put it on a barge to Hanford where the rest of the decommissioned submarine RX compartments sit and then rebuild the plant, than it would be to clean and try to inspect everything.
Hi Ms Perps and any (like Matt) that seem to think I’m an anti-nuclear troll, Huw’s got my back. Yes, I remain convinced that nukes are the only way to solve global warming and peak oil with today’s technology. I’m not talking about my own personal reaction but the *public* reaction.
They saw a ‘nuclear building’ explode. Add Addinal’s description of geiger counters sniffing babies, and that will settle it for many. They won’t care about Level 4 distinctions. People are often just too busy to look into these details. Most people I meet are not ‘bloggers’ and don’t really care about energy and sustainability issues. They’re sucking down beer as they watch the sport, and worrying how much this carbon tax is going to cost them. I get the impression that maybe 20% or 30% of the people I meet actually believe climate change is all a greenie power grab, and the tax confirms it. Their views on energy issues are decided for them by carefully crafted 10 word sound-bytes from anti-nuke activists. Or, as I was saying earlier, from spectacular visual events like this Japanese ‘nuclear thing exploding!’
It all depends on how the media handle it from here. The media LOVE a disaster, and hate Barry’s approach of level headed analysis. Boo, hiss, boring! It doesn’t make for a 10 word sound byte or snappy headline! Careful analysis might one day get explored on a show like Catalyst, but will Channel 7 or 9 or 10 run it? I don’t think so.
As Addinall said:
///I am afraid the media and the usual culprits from the Dark Greens are not letting go of this.///
What kind of ‘analysis’ do we see of these matters on Neighbours or Home and Away? Sadly, that’s the kind of media penetration we’re after.
So unless we see headlines like “INDESTRUCTIBLE Japanese Core proves nuclear safety” I think the media ‘fallout’ will settle the case for many.
“KEVIN RUDD has called for urgent briefings from Japan on the threat posed by an explosion at a nuclear plant and said Australia had offered Tokyo atomic expertise.”
Now THAT was genuinely FUNNY!
> containment
You’re right, em1ss, thank you.
Here’s a picture identifying Fukushima Daiichi 1 as you describe: http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
Larger: http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
from http://www.nei.org/howitworks/boiling-water-reactor-design
So in these terms, the secondary containment blew off. But in this PWR-2 design, the building doesn’t really “contain” -it’s not air tight in this old design.
In a newer design the secondary containment would be a sealed building, often with the typical dome, giving an actual second layer of real containment.
I was thinking of the reactor pressure vessel as a “containment” — it’s not, although it is a closed container.
> spent fuel
When used rods are first removed, I think they are temporarily put in the water tank container in the reactor building itself, up near the top of the reactor under the crane; I and others had earlier confused with the “spent fuel pool” but is only a brief holding area (no idea if it had any fuel rods in it as of this time-some bloggers out there were speculating that fuel rods stored there would be exposed after the explosion)
The “spent fuel pool” is pictured in the powerpoint file I linked above (session-10b-japan-1.ppt), described as “A large-scale pool 12m x 29m x 11m(depth) fuels more than 19-month
cooling”; used to cool rods down; and after that there’s the dry cask storage.
The reactor performed as designed to the earthquake, the emergency diesel generator was not designed to run under water. Thus for the want of a nail……..
The pool basin Spent Nuclear Fuel inventory for the Vermont Yankee BWR Mark I reactor which went on line in 1969 and it is about 690 MTHM containing ~75.6 Mega Ci, predominantly Cs-137 and Sr. 90.
Ah, there was a better description in the doc I linked long ago, only yesterday: “the reactor building, which doubles as a secondary containment….”
http://www.ansn-jp.org/jneslibrary/npp2.pdf
“The primary containment vessel encloses the reactor pressure vessel, other primary components and piping. … The containment is a reinforced concrete containment vessel (RCCV) with a leak tight steel lining. The containment is surrounded by the reactor building, which doubles as a secondary containment. A negative pressure is maintained in the reactor building to direct any radioactive release from the containment to a gas treatment system. The reactor building and the containment are integrated to improve the seismic response of the building and the containment are integrated to improve the seismic response of the building without additional increase in the size and load bearing capability of the walls….”
Er, this one that’s got the worst problems is a “BWR-3″ design — from the same npp2.pdf file, showing the timeline of development:
“7×7 type fuel development (high power density and long fuel rod) Fukushima I-1 (BWR-3)”
I don’t see a mention of this morning’s ‘Sunrise’ TV program which seemed to give a balanced view. A couple of journos talked about the role of containment vessels and the problems with coal as an alternative. They interviewed anti-establishment economics academic Steve Keen who predicted the 2008 GFC when others failed to see it coming. Keen argued the case for thorium reactors.
When the dust settles it will be interesting to compare nuclear harm with that of natural forces, several injuries vs thousands of deaths. Not good enough apparently.
John Newlands, on 13 March 2011 at 1:01 PM — GFC?
Argh: “http://discussions.latimes.com/20/lanews/la-sci-japan-quake-sixth-reactor-20110313/10″ says “Fukushima No. 1, also known as Fukushima Daiichi, which was disabled by an explosion overnight that destroyed the building housing the reactor and the backup cooling system.”
Way wrong. Very confused. I got a comment in pointing to
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
which has pictures making clear that the reactor building just lost its top, but look how easily confusion arises about what’s what
Quoting from the World Nuclear News page:
“Later television shots showed a naked steel frame remaining at the top of the reactor building. The external building structure does not act as the containment, which is an airtight engineered boundary within….”
and
“Chief cabinet secretary Yukio Edano appeared on television to clarify that the explosion had damaged the walls and roof of the reactor building but had not compromised the containment.”
—-
Bottom line — there’s no “secondary containment” now and no negative air pressure because the building’s lost its top. Might as well refer to “the containment” if you’re pointing people to descriptions to clarify what’s there.
http://www.tepco.co.jp/en/press/corp-com/release/11031304-e.html
* High Pressure Coolant Injection System of Unit 3 automatically stopped. We endeavored to restart the Reactor Core Isolation Cooling System but failed. Also, we could not confirm the water inflow of Emergency Core Cooling System. … reported … at 5:58AM, Mar 13.
In order to fully secure safety, we operated the vent valve to reduce the
pressure of the reactor containment vessels (partial release of air
containing radioactive materials) and completed the procedure at 8:41AM,
Mar 13,
Unit 1 is a GE BWR 3 with Mark 1 Containment. Major concern with a Mark 1 Containment is primary containment volume size and heat removal capacity via the torus. Secondary Containment remains the same in all BWR 3-6 designs as reactor building and it’s ventilation systems.
Hence why they modified the Mark 1 Containment (Torus vs Suppression chamber) design to provide an over pressure vent capability directly from the Torus to the exhaust stack. That vent would contain fission product gas along with hydrogen. The vent is not connected to the Reactor Building (secondary Containment) ventilation system like newer BWR designs. Specifically it is not passed though the Standby Gas system first prior to release.
Fission product barriers (protect the public) and estimated status based on reports are as follows:
Fuel Pellet – indeterminate without specific coolant sample results but fission product gasses do not indicate gross fuel failure
Fuel Clad – leakage is indicated due to Fission Product gasses present on venting. Any clad leakage would result in an increase though even if minor. Plants operate with leaking fuel rod clad on pins. They just suppress the power near that bundle.
Reactor vessel and coolant system – no indication of failure yet reported.
Primary Containment – Torus and Drywell – no indication of failure yet reported.
Secondary Containment – Reactor Building and Ventilation systems – failed, walls gone due to hydrogen explosion. Why protecting the vessel and primary containment is so important.
James and I chased this out to earlier today. I had an SRO cert on a similar design.
I am concerned about the spent fuel pool status. They must keep it full, re-establish cooling and ventilation boundaries to the environment.
This unit is likely finished operationally in my opinion. No return from direct seawater flooding of the containment.
Hank HPCI loss is predictable based on decay heat lowering. HPCI can only run at a certain steam pressure, RCIC can run lower but still requires boiling.
Quite. What has this earthquake taught us? That it’s much, much risker to choose to live next to the ocean than it is to live next to a nuclear power station. But I wonder whether that message will ever get through.
Hi all,
being in a career-change etc I don’t have time to read the ins and outs of every single media report on this, so I’m hoping Barry can summarise the gist of it all above when I come back to this topic in a week or so?
Thanks all for your tireless work on this.
Where did the cesium and iodine come from ? does that not indicate fuel failure ?
Daini Unit 3 is in a safe, cold shutdown, according to Japanese officials (despite some earlier unfounded reports).
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
Hank Roberts, on 13 March 2011 at 1:13 PM — The explosion seems to have just removed the sheet metal walls and roof of the penthouse. The concrete ‘secondary containment’ still ovbiously has walls; I doubt the concrete roof was damaged.
Sidd, read the thread. Cesnium and Iodine are normal fission product gases that build up inside the fuel rod during operation. Any fuel clad leakage and they leak out. Operating SRVs (Safety Relief Valves) from the Reactor to the Torus puts them in Containment. Venting the Contaiment puts them out the stack to the atmosphere. Key is level observed, high gross fuel failure, low fuel clad leakage.
DB GFC = global financial crisis = ‘financial meltdown’
My point about the [ad hom deleted]economist is that he appears to have an eerie sixth sense so people take notice. He says thorium is the way to go.
Top post updated with latest news.
Well said Barry. Living near a nuclear plant is safer than most other industrial sites.
Dave, not knowing the specific design but working off typical designs. The upper level of a BWR Reactor Building is not as hardened a concrete structure and would fail first on an internal explosion. The lower levels and ECCS rooms would be significantly hardened structurally.
Barry,
In a battle between facts and emotions, emotions wins every time, and no matter what the facts are this is huge blow for the nuclear insutry here (and probably around the world). It might be safer to live near a nuclrar power station than the ocean, but people will now be even more scared of nuclear power.
Hawkmon, yes, that is a real possibility, as least in some places. In which case, Australia will keep on burning coal and gas. Still, the global picture is of much bigger importance from a climate change mitigation perspective, and in that context, I see no significant alteration of the current trajectory.
Meanwhile, a few hundred kilometres away, we have this:
Cosmo Oil refinery fire
“In a battle between facts and emotions, emotions wins every time, and no matter what the facts are this is huge blow for the nuclear insutry here (and probably around the world). It might be safer to live near a nuclrar power station than the ocean, but people will now be even more scared of nuclear power.”
The first thing we must understand is that what we are going to be told by statements made [ ad hom deleted]about what the public’s opinion on this matter is unlikely to be true. As I have pointed out here before, public opinion on nuclear energy is a function of public understanding, and it is not by any means uniform. We are going to see interviews, and sound bites by individuals identified as spokespersons for antinuclear groups with impressive sounding names, that will claim to be speaking for the majority. The reality is that these groups are most often little more than one or two people, a web page, and a P.O. box. They are however always available to the media for a quick statement, having cultivated reporters in their area to that end.
I was stunned to see an absolute nobody from the Toronto area being tooted as an expert on nuclear matters, interviewed on the CBC National News. [ad hom deleted] as he called for the closure of all nuclear power stations in Canada in the wake of what was occurring in Japan. However I must say that I was pleased to also see that Discovery Canada sent a senior reporter to ask intelligent questions to the head of Bruce Power about the incident, and its implications for Canadian nuclear plants. This interview was broadcast on Daily Planet, Discovery’s nightly science news show.
The lesson here is that we need to have our own spokespeople available to meet with the media on demand. Barry Brook has already positioned himself as the pronuclear go-to guy down there, but we need more credible people to take up this mantel in other countries.
Agreed DV8. I have done a dozen TV and radio interviews so far, and talked to various newspaper journos. Most, rather than being irked by my ‘just the facts’ approached, seemed quite relieved and probed me quite a bit with sensible questions. But my few short segments are being overwhelmed by the huge amount of hysteria being generated elsewhere, by both those who are being deliberately deceptive to suit their own ends, and those who just plain don’t know better. This is a tough battle ahead, for reality to trump hype and we need as many troops on the ground as possible. This is the time to sell the truth and push nuclear power forward as a rational solution, rather than be put on the back foot for another decade.
Sorry Barry, I definitely can’t help as a spokesman, company rules for now. Until I retire at least. 29 years of nuclear power operations, 2 years combined gas turbine and likely 5-7 to go.
It will be a shame if the media turns this into a major disaster and sets back what needs to be done world wide to divorce ourselves from fossil fuels and their effects on the environment.
Google Earth is acquiring imagery and has mapped the evacuation zones:
http://maps.google.com/maps/ms?vps=2&jsv=322a&ie=UTF8&msa=0&output=nl&msid=216710817486487714534.00049e3c98b2d448
David, the top of the primary containment is shown in the picture — it’s the hatch used by the fuel loading crane — labeled here: http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
great image hank, notice how the upper structure of the Reactor building is not hardened…. It clearly shows how a hydrogen explosion pressurization would result in the damage that occurred.
Good to have your comments anyway em1ss, very much appreciated.
Talking of beyond design basis, the earthquake is now considered to be the largest earthquake within the boundaries of the North American and Pacific tectonic plates in 1,200 years (unverified).
When you see people refer to “Unit 3″ and they’re confused — refer them to the press release and point out how similar the names are.
Daiichi Unit 3 has a cooling system failure now;
Daini Units 1-4 are venting to reduce pressure;
Daini Unit 3 has a “hot stop” (whatever that is):
http://www.tepco.co.jp/en/press/corp-com/release/11031304-e.html
Fukushima Daiichi Nuclear Power Station:
* High Pressure Coolant Injection System of Unit 3 automatically stopped. We endeavored to restart ….”
…
Fukushima Daini Nuclear Power Station:
Units 1 to 4: shutdown due to earthquake …
* At present, we have decided to prepare implementing measures to reduce the pressure of the reactor containment vessel (partial discharge of air containing radioactive materials) in order to fully secure safety. These measures are considered to be implemented in Units 1, 2 and 3 ….
* Unit 3 has been stopped and being “nuclear reactor cooling hot stop” at 12:15PM.
Thinking out loud here but Hydrogen is lighter than air, without power for Reactor Building Ventilation is it possible it collected in the upper levels near the refuel floor. Possibly they were trying to make up to the fuel pool by some type of temporaty injection and caused the explosion?
Hank Roberts, on 13 March 2011 at 2:05 PM — Thanks, I hadn’t noticed that detail.
Here I am on the Today show (Ch 9 TV) talking about Fukushima situation, Japan: http://video.au.msn.com/watch/video/explosion-fear/xqk4in1
Good job Barry.
Grrr, nuclear spokesman Joseph Cirincione from Ploughshare Funds…. Think they have an agenda?
http://www.ploughshares.org/
Thanks for the great discussion everyone. It’s been a refreshing change from the rest of the news I’ve been reading online.
I am curious what the worst case scenario is now? If the plant is off and cooling down, what is important about getting it to cool faster (e.g. pumping in sea water)? If it doesn’t cool down faster will something occur?
I suppose I am just wondering if it is still possible (if everything went wrong from here on out) that we will end up with a large uninhabitable zone like Chernobyl?
New update from World Nuclear News
Barry – you were superb on Channel 9 this morning. I’m posting the video of you around facebook and on blogs.
http://video.au.msn.com/watch/video/explosion-fear/xqk4in1
Can anyone reconcile the IAEA page Barry posted just above: 0235 CET, 13 March 2011 — which now says: “CORRECTED An earlier version of this release incorrectly described pressure venting actions at Units 1, 2, and 4 at the Fukushima Daini nuclear power plant. Venting did not occur at these units.
Japanese authorities have informed the IAEA that Units 1, 2, and 4 at the Fukushima Daini retain off-site power. Daini Unit 3 is in a safe, cold shutdown”
compared to the press release from TEPCO (Mar 13,2011) quoted above, that’s contradictory on all those points?
Anyone know what a “hot stop” is? I find it mentioned but not defined in one reactor transient problem report. Nothing else.
I don’t subscribe to addinall’s brand of [ad hom deleted]fatalism. Like abundant snowfall due to increased water vapor, this is a teaching moment. Please correct me if I’m wrong, but loss of coolant flow is not a serious problem with liquid sodium reactors, right? This is a very good opportunity to point out the advantages of FBR designs.
I believe the problem with liquid sodium reactors is the activity issue with a loss of coolant accident. Sodium becomes highly activated when used as a coolant. At least that was the problem years ago.
http://en.wikipedia.org/wiki/Liquid_metal_cooled_reactor
The Australian Greens leader Bob Brown and the Australian Conservation Foundation nuclear spokesman Dave Sweeney decide that this incident provides a good opportunity to rip into the nuclear power option.
http://www.abc.net.au/news/stories/2011/03/13/3162740.htm
Hypocritical given that Bob Brown thought immigration policy discussion was inappropriate immediately after the Christmas island shipwreck.
The problem with nukes seems to be the element of risk associated with it. The procedures established call for evacuation nearby. Currently though the risk of major environmental radiation pollution looks small – the practical effect of evacuating 200,000 people is HUGE.
So, I’d never-ever want to live near a nuke plant – not because of radiation risk but because of evacuation risk. I already live in an earthquake zone – don’t want to tag along another risk.
So government instructions are now mentioned in the latest TEPCO press release:
Press Release (Mar 13,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 9am March 13th)
All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.
Unit 1 (Shut down)
– Reactor has been shut down. However, the unit is under inspection due to the explosive sound and white smoke that was confirmed after the big quake occurred at 3:36PM.
– We have been injecting sea water and boric acid which absorbs neutron into the reactor core.
Unit 2(Shut down)
– Reactor has been shut down and Reactor Core Isolation Cooling System has been injecting water to the reactor. Current reactor water level is lower than normal level, but the water level is steady. After fully securing safety, we are preparing to implement a measure to reduce the pressure of the reactor containment vessels under the instruction of the national government.
Unit 3(Shut down)
– Reactor has been shut down. However, High Pressure Core Injection System has been automatically shut down and water injection to the reactor is currently interrupted. We are examining alternative way to inject water.
Also, following the instruction by the government and with fully securing safety, steps to lowering the pressure of reactor containment vessel has been taken. Spraying in order to lower pressure level within the reactor containment vessel has been cancelled….
http://www.scientificamerican.com/article.cfm?id=fukushima-core&page=2
Nuclear Experts Explain Worst-Case Scenario at Fukushima Power Plant
Here are some links showing why I am concerned about the spent fuel pool. Based on the latest photos this area has to be exposed and a complete mess. This is typically the upper most level in a BWR Reactor Building.
http://www.nucleartourist.com/images/rflg-fl1.jpg
http://www.nucleartourist.com/images/rflg-fl2.jpg
Additionally this may be part of the smoking gun for the hydrogen explosion as reported during injection.
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0933/sec3/195.html
I’m on comment restrictions at John Quiggins blog. So if somebody else wants to take on the anti-nuke comments there that would be a good thing:-
http://johnquiggin.com/index.php/archives/2011/03/12/earthquaketsunami-in-japan
@Barry, calm and reassuring on Channel 9 thanks. And hat tip to em1ss for sharing your knowhow.
@Barry. Good video.
Here is a REALLY BAD article that has just popped up on the Australian.
http://www.theaustralian.com.au/more-bodies-found-as-japans-nuclear-crisis-worsens/story-fn84naht-1226020635376
“JAPAN battled a feared meltdown of two reactors at a quake-hit nuclear plant, as the full horror of the disaster emerged on the ravaged northeast coast, with thousands feared dead.”
Hmmmm. Implies causation. And the rest of the article never once tries to separate the two.
Read it. It is quite ill-making.
NEI and NRC have merged to form the “NEIRC”, according to New York Times editors:
http://www.nytimes.com/interactive/2011/03/12/world/asia/the-explosion-at-the-japanese-reactor.html?ref=asia
Hey everyone.
I am just trying to get back up to date on what is going on. I found a pic on wikipedia, of the reactor building post:
http://upload.wikimedia.org/wikipedia/en/9/9b/2011-03-12_1800_NHK_S%C5%8Dg%C5%8D_channel_news_program_screen_shot.jpg
It looks like the only thing left is the top of the drywell. Does anyone have data on the intergrity of the spent fuel pools, it looks like everything at the reactorfueling level is gone, with only thing being the “socket” of the drywell
I am also very scared of a H2 bubble in the top of the drywell, it seems likely that a H2 bubble has formed and probably cant be vented via Direct Torus vent.
em1ss, I need your expert consult:
if they drainded the spent fuel pool, what is the time to zirconium combustion? Can you give a update on the state of the reactor and cooling?
NHK press conference
Some interesting news about Reactor 3.
1. They noticed water level had declined at 9:05 am so they lowered pressure the pressure and then started injecting water fresh water by use of a pump.
2. Trouble occurred with the pump which required them to seawater.
3. Injecting seawater was unstable in the beginning and the water level went lower and core was not fully cover by water and not fully cooled. But only for a short time.
4. They soon stabilized it and brought the water level back up and the fuel core was completely covered.
5. Part of the core within the reactor is deforming because of they were exposed outside water. But it wasn’t long enough for it to melt.
6. Afterwards, huge amount of Hydrogen was generated because of the exposed fuel core. And they observed that to have collected in the upper part of the container.
7. They believe the hydrogen that caused the explosion of reactor 1 was generated in the same manner. And collected in the upper part of the outer container as well.
8. There wasn’t an explosion this time because the ventilation was functioning in reactor 3. Ventilation wasn’t working in reactor 1.
9. Noted that when decision to use seawater was made, it’s also understood that the reactor would never be used again. The, seawater cools the reactor but it becomes extremely difficult to
10. Sounds like they might use seawater on all of the reactors and close the entire plant.
The cores in Reactors 1 and 3 both spend some time uncovered. And the core in reactor 1 is damaged but they don’t know the extent of it of the damage.
Also at 1pm there was a radiation reading of 1557 microsvrs. It’s equivalent to 3 stomach xrays.
It had dropped to 184 by 2pm and it’s current at 15.
I definitely got the feeling the worst of it is over now.
> It looks like the only thing left is the
> top of the drywell.
That’s well above the top of the fuel pool. Look earlier in this thread, at the picture:
http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
You can see the deep pool to the right of the reactor bottle. It’s way below the level that blew off. There’s a yellow bar across the top of it, and little rectangles at the bottom that must represent fuel, deep down under the water level.
That’s assuming the water’s still there — but that would be hard to miss.
Still, it’s a shame everyone’s guessing. I started writing yesterday in the older topic titled “An informed public is key to acceptance of nuclear energy” — hoping this would happen.
It’s not happening very well. Way too much opportunity lost to actually explain how things work, how they’re put together, how these designs have changed since 40 years ago — and as Barry notes, how this 40-year-old design held together in a quake far above its design maximum.
Crisis/opportunity.
A better diagram showing the location of the fuel storage pool, labeled in this diagram. I think this is a repeat posted earlier:
https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf
from
http://uvdiv.blogspot.com/2011/03/some-links-on-fukushima-daiichi-1.html
The fuel in the early stages of this incident and the 3 Mile Island incident does not melt. Early in the incident when the fuel is standing in the steam environment the temperature raises to 800 – 900 oC. At these temperatures, the protective black oxide film on the zircalloy tubing is lost by dissolving into the base metal. Then rapid corrosion with formation of thick white oxide flakes occurs and the tubes can crumble in minutes.
pg 450 of http://books.google.com/books?id=gikdjXLfsVEC&pg=PA77&lpg=PA77&dq=zirconium+oxide+diffusion&source=bl&ots=Y2kLvpaTZc&sig=GfRnQCdgpcAMK39UrgWD2-V2fhU&hl=en&ei=22x8TaXBFMf4rAHd6oHMBQ&sa=X&oi=book_result&ct=result&resnum=10&sqi=2&ved=0CFIQ6AEwCQ#v=onepage&q=zirconium%20oxide%20diffusion&f=false
The crumbled fuel drops to the bottom of the reactor vessel and you should have boric acid present as the configuration at the bottom of the reactor vessel is not controlled by geometry or even have control rod poison present. Late in the event, all the water will boil off around the mixed zirconium and uranium oxides and the hot oxides can proceed to melt with the adjoining steel vessel. Three Mile Island melted assorted metal devices that were through the oxide mass. It did not get to melting the pressure vessel before they quenched it.
So now, we have stubs of zirc clad fuel standing up with zirc oxide and fuel pellets scattered around, between and below the stubs.
The hydrogen accumulation is unit 3 is a concern, and must be relieved in a controlled manner. It’s too early to say much more on this. Overall, there are some salient lessons to be learned from this event for BWRs, and for the siting of backup generation in older reactor sites at sea level, which don’t include passive emergency cooling systems like Gen III designs.
This article from the BBC gives a sensible and accurate analysis of the current situation. I wish the Australian media showed the same restraint and application to truth rather than innuendo,
http://www.bbc.co.uk/news/world-12723092
http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm
Aerial pictures Fukushima nuclear plant, before & after tsunami.
[…] Posts Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquakeAn informed public is key to acceptance of nuclear energyOpen Thread 9 – technosolar catastrophe?IFR […]
[…] Brook posted a 12 March comment that illuminates our understanding of “how big is that earthquake”. Real-time, […]
New short summary from WNN:
[…] the internet and media right now about the Fukushima nuclear reactor situation. In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, as well […]
Hallo all ,
first let me thank for the excellent informations and the discussion in this thread.
Also for the excellent aggregation of the event here
http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/
Would be great to spread this information.
Even iam more on the contra side of actual nuclear power plants , here in germany we have a lot of old ones and final storage is also not solved. I prever to stay on the rational side (where ever this is 😉 ).
But this accident opens for me some questions ?
How could it be that in a known tsunami area the back up power systems are not secured against?
How could it be that in 3 out of 4 (at least i think so correct me if not so) suffer the same problems when there is always told that the systems are redundant (single point of failure ?) ?
Why this importent information you people gave me , is not available on an offical side from tapco or the japanese government. (What imho is at least partly the reason for the reaction of media).
So many greatings from germany and please forgive my horrible english.
Thomas WAlter
P.S I was the first time on this webpage but for shure not the last time
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
At the top of the building you see the refueling floor area. The crane for reactor dissassembly is shown in orange. The Spent Fuel Pool is below the refuel floor surface.
The walls blown off the Reactor Building were essentially at refuel floor level and are not as robust as the balance of the building. The Spent Fuel Pool is a robust concrete structure that is steel lined.
The water in the pool provides cooling and radiation shielding. Loss of water level in the Spent Fuel Pool would remove shielding and cause a significant increase in measured radiation levels on site and at the site boundary. That has not been reported as occurring yet.
As long as water level can be maintained the pool will evaporate due to decay heat and remove heat from the spent fuel. Just have to maintain makeup water and level.
How long the spent fuel has been in the pool since removal from the core determines decay heat load. Spent fuel is held for decay in the pool and when enough decay years have passed it is then loaded into dry fuel storage casks.
The link below provides some US information on dry fuel storage. There are even U-Tube videos out there on it.
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/dry-cask-storage.html
BBC news is reporting that a state of emergency has been declared at Onagawa nuclear power plant. Source IAEA. No further details.
“The risk of meltdown is extremely small, and the death toll from any such accident, even if it occurred, will be zero. There will be no breach of containment and no release of radioactivity beyond, at the very most, some venting of mildly radioactive steam to relieve pressure. Those spreading FUD at the moment will be the ones left with egg on their faces.
I am happy to be quoted forever after on the above if I am wrong… but I won’t be.”
this is a sincere question, but just as a casual observer trying to grasp the severity of the situation, i have to ask the following:
given the latest updates on the matter, is it safe to assume that Barry’s assessment at the time has proven to be wrong? or at best not completely the most accurate?
because if this is the case, every last ounce of optimism has just gone out the window for me. please say it ain’t so.
Based on what we know so far, I’d say Barry is closer to the truth than much of the media reports. The reporters don’t understand what they are being told in a technical sense and often link the facts with death tolls from the quake etc for effect.
Although things could change with another quake etc., the plant operators are responding pretty well considering the multiple concurrent events that occurred beyond the design basis of the plants. The evacuation zone has been conservative and the public exposure risk has been minimized. Lack of electric power has been the limiting factor in response to the events.
The facts will all come out in the end, but the media won’t print it. It won’t be headline news. It will be shared throughout the nuclear industry in detail to capture any lessons learned.
Update on Onagawa via BBC. It seems it is a Level 1 incident with the detection of some sort of radiation leak.
brucerhee,
I’d say that Barry’s assessment is still more or less correct. There does not seem to have been a major radiation release on the scale that poses a serious threat to public health.
[…] websites: http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
If anything comes out of this it will likely be a change in emergency power sources. Hardened gas turbine units above ground that are duel fuel, gas or oil may be more prudent for units along the coastline. They don’t need cooling water.
Hopefully the Onagawa plant is just venting and the levels will drop. No details available yet.
Has there been any statement about precisely why the diesel generators at Fukushima Daiichi failed? The IAEA said it was the tsunami, but what was the mechanism?
Hmmm, good time line link here. It seems they are pumping seawater now into three units. They obviously still are lacking electric power to combat the event.
http://www.bbc.co.uk/news/science-environment-12722719
Tsunami depth: http://www.lataco.com/taco/wp-content/uploads/tsunami_energy_map_pacific.jpeg
Quote “Also at 1pm there was a radiation reading of 1557 microsvrs. It’s equivalent to 3 stomach xrays.”
Stomach xrays only last a matter of seconds so would it be correct to say it would be like a Stomach xray in which the doctor has forgotten to switch the machine off?
Wow, nothing changed overnight? Pointer please if there is a current summary that’s not mentioned here? Just woke up and the radio sounds like much is new but it’s vague what if anything happened since 8 hours ago.
Perhaps the diesel fuel was contaminated by sea water. Who knows.
Mr Goto said the reactors at the Fukushima-Daiichi nuclear plant were suffering pressure build-ups way beyond that for which they were designed. There was a severe risk of an explosion, with radioactive material being strewn over a very wide area – beyond the 20km evacuation zone set up by the authorities – he added. Mr Goto calculated that because Reactor No 3 at Fukushima-Daiichi – where pressure is rising and there is a risk of an explosion – used a type of fuel known as Mox, a mixture of plutonium oxide and uranium oxide, the radioactive fallout from any meltdown might be twice as bad.
> why the diesel generators at Fukushima Daiichi
> failed? … what was the mechanism?
I posted this in the other thread yesterday:
“CNN: “Crews had difficulty generating enough electricity to pump water into the facility ….
Janie Eudy told CNN that her husband …. As he and others were planning to evacuate, at their managers’ orders, tsunami waves struck and washed buildings from the nearby town past the plant.”
Satellite before and after the tsunami, including a closeup of the power plant (page down) — you can see how much got moved around right up to the four big square buildings housing the reactors. I’d guess the diesel generators must have been at ground level.
http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm
This is also a reminder for us at a distance focusing on the power plants, that there’s far more devastation over a wide area.
And it makes me think about what Seattle or Port Townsend or Vancouver or Portland will look like, after the next big subduction earthquake on the other side of the Pacific — which is also due by about now.
[…] Discussion thread at Brave New Climate […]
Good writeup here and perspective of event as it stands currently.
http://www.thedailybeast.com/blogs-and-stories/2011-03-12/japan-nuclear-fallout-how-bad-could-it-get/
Here’s an exerpt from the following link.
Dale Klein, a former chairman of the NRC, said in an interview Saturday that using seawater to flood Fukushima Daiichi-1′s reactor core-and containment as a precautionary measure-is part of the plant’s emergency planning process. “If you’re near the end of your options, that’s one of them,” he said.
Klein said such a procedure leads him to believe the condensate tank was broken or empty or the pipes leading to it were broken because it would have been used otherwise. The condensate tank is used to provide water to the emergency core cooling system.
Klein, who chaired the NRC from July 2006 to May 2009, said future operation of the reactor “would be an economic decision that Tepco would have to make.” But he said that it was his guess that the company would consider building a new one instead. “It would be a major cleanup of contaminated components and water,” he said. The 460-MW unit 1 at Fukushima Daiichi (or Fukushima I) began commercial operation in 1971 and is the oldest and smallest of the Fukushima reactors.
Klein said he would characterize the quake impact on Fukushima I-1 as “more like a Three Mile Island [but] with a lot more knowledge.” Operators at the Japanese unit “knew early on what they had to do, they just had trouble doing it.” he said.
During the accident at the Three Mile Island-2 unit in Pennsylvania on March 28, 1979, operators mistakenly turned off the emergency core cooling system, which had automatically activated, because they erroneously believed the core was covered. The TMI-2 accident — in which there was a partial core meltdown — is considered the worst in US commercial nuclear power plant history but led to no deaths or injuries to plant workers, according to NRC.
The workers at Fukushima I-1 set up emergency diesel generators to provide backup power for the cooling system, but they apparently ran for only a short time before being damaged by the tsunami, Klein said. Backup power could have been provided by batteries but that typically lasts only a few hours, and damage to the surrounding area appears to have cut off the option of bringing in additional emergency diesel generators, he said. “The earthquake had minimal impact; the tsunami had the impact,” Klein said.
At early-afternoon EST Saturday, Klein said he believed there would be few fatalities due to the reactor itself, although he said the hydrogen explosion could have injured people in the plant. “I think this will be remembered for the fatalities from the quake and tsunami, not from the reactor,” he said.
http://www.platts.com/weblog/oilblog/2011/03/13/whats_going_on.html
Just a drive-by, keep up the good work, this is one of a fairly small number of sources presenting credible well-referenced information rather than rumour and scaremongering.
em1ss, I’m talking about a loss of coolant *flow*, like in this situation with the failure of the pumps, not a loss of coolant. Yes, one drawback with liquid sodium is its reactivity with air (and water). That’s not the issue here. From what I’ve been reading about liquid metal reactor designs, even if the pumps are out and the coolant is not flowing, the thermal properties are such that overheating will not occur.
Yes Sodium has that advantage thermally, but I still believe it has a higher activation rate, so overall radiation levels and activity from leaks is a concern….
Much the reason the US navy abandoned it after the Seawolf early on as a moderator.
How did the seemingly large amount of H2 get out of the reactor core (where it would have been generated by very high temperatures in reaction perhaps between zirconium alloy and water? Would this not suggest a severe breach of the core containment vessel and would the release of such quantities of gas from the core not have carried radiative contamination into the ensuing explosion?
Samoht, this was discussed earlier in the thread. The Hydrogen got out of the vessel via Safety Relief Valve (SRVs)openings to the Torus (Suppression Chamber) to control Reactor Pressure and allow injection with low pressure sources. Decay heat was the enemy.
> Samoht, on 14 March 2011 at 5:12 AM said:
> How did the seemingly large amount of H2 get out
Intentionally — through the valves opened to reduce pressure inside the containment. As of March 12:
“… TEPCO said it managed to release pressure in the No. 1 reactor’s containment building.
….. The company was working to intentionally release radioactive vapor via escape valves … to lower the unusually high pressure inside.
Workers tried to manually open valves to release vapor, but initially ran into trouble due to unexpectedly high radioactivity levels ….”
http://www.yomiuri.co.jp/dy/national/20110312dy01.htm
> Would this not suggest a severe breach
No. An unusually large amount of gas is a sign of some damage, cracks on the waterproof outside cover of the fuel let water react with the hot metal.
And
No. Generating enough gas to raise the pressure inside — as did happen — means the gas is _staying_ inside the reactor.
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Here’s a further annotated version of the now-familiar image, showing the spent fuel storage tank alongside the upper end of the reactor vessel (below the big crane):
http://i54.tinypic.com/m75aol.png
Hat tip to this post-a good summary:
http://www.housepricecrash.co.uk/forum/index.php?showtopic=160968&view=findpost&p=2924962
which begins
“Right then. Who wants to know what actually happened? …. we need to look at the design of the reactor itself. I have been unable to find a decent diagram of the actual reactor at Fukushima, but here is a similar reactor, taken from the United States Nuclear Regulatory Comission’s Reactor Concepts Manual….”
Night all, work tomorrow and lets pray for:
* the people still suffering in Japan due to the Quake and the Tsunami.
* the operators battling decay heat at the nuclear plants.
* no more acts of nature to inflict more damage.
Good info here:
Insights into the Control of the Release of Iodine, Cesium, Strontium and other Fission Products in the Containment by Severe Accident …
http://www.oecd-nea.org/nsd/docs/2000/csni-r2000-9.pdf
Goes through the sequence of events and the temperatures and chemistry and type of damage and products expected to be coming off; describes boiling and pressurized water reactors.
Index of docs from the site:
http://www.oecd-nea.org/nsd/docs/indexcsni.html
PS, from the csni-r2000-9 doc, this sounds like the approach being used for the damaged reactors in Japan:
“There is thought now that especially for reactors with fuel having a low power density it may be possible to arrest accidents by simultaneously providing coolant to the core and by cooling the outside of the reactor vessel [S-14]. The radionuclide release consequences of prolonged retention of core debris in the reactor vessel have not received much attention.”
And this:
“A source of fission products to the reactor containment that is not often considered is release from a spent fuel pool located within the containment when pool cooling and residual heat removal cannot be maintained. This configuration of the spent fuel pool within the containment is found in the VVER-1000 reactors. Overheated fuel in the spent fuel pool can undergo gap release, release of radionuclides during fuel degradation and release as a result of molten fuel interactions with concrete. Physical and chemical phenomena associated with these stages of release are likely to be quite similar to releases usually considered in safety analyses except the ambient atmosphere will be air rather than steam [S-25]. No detailed analyses of severe fuel degradation and radionuclide release during accidents involving fuel in a spent fuel pool like that found in VVER-1000 reactors have been published.”
and
“The simplest categorisation is to treat the radionuclides that could be released from a nuclear power plant as a mixture of noble gases, gaseous iodine, cesium particulate and other particulate. Little can be done by way of accident management to attenuate the release of noble gases3 except to reduce the leakage from the reactor containment (See Chapter VII). Gaseous iodine release can be attenuated by trapping in water, adsorption on surfaces, chemical transformations and filtration (See Chapter VI). Most of the source term measures of accident management are focused on reducing the amounts of radioactive particulate that can be released from the reactor and discussions of the physical and chemical bases of these measures make up much of the rest of this document.
fn3. There have been studies of methods to trap noble gases. In the main, absorption methods using zeolites or charcoal have been examined. Though the noble gases will absorb on these materials, it has proved challenging to engineer systems that will operate well under the range of conditions expected to arise in severe accidents.
________
And again from the same document, this definition of “gap release” — which may be as far as these accidents go down the path toward ‘severe’ accidents, if the cooling by flooding seawater works.
“Gap release
Once an accident is initiated, coolant levels drop below the top of the active fuel. The cladding on the fuel ruptures and the gap inventory of radionuclides is released to the flow through the reactor coolant system. The gap release consists primarily of noble gases and the more volatile radionuclides such as cesium, iodine, and perhaps tellurium. Some finely fragmented fuel particles may also be released. Gap inventories have been the subject of debate for the last 20 years [S-6]. Some of the best experimental studies of gap release have been reported by Malinauskus and coworkers….”
___________
The concern with the noble gases is that they don’t react chemically so are hard to capture, and the radioactive gas isotopes spread in the air for a while then decay later into solids.
From a discussion about detecting products of undeground nuclear tests:
http://www.idealist.ws/nokonuketest.php
“… cesium 137 and strontium 90 tend to become distributed more widely than their fission byproduct peers – in a leak or vent – primarily because: a) their precursors gases are able to expand and rise rapidly while other nongaseous particles will have fallen to the ground and (b) these gases also escape the fate, of other fission byproducts, of (their or their decay products) being fused to surfaces or other particulates and thus gaining additional mass.
Krypton and Xenon Gases
Most radioactive products from any fission activity, including a nuclear blast, ‘began’ as a krypton or a xenon gas. All such gases are radioactive and xenons and kryptons can linger in the air for minutes, hours or years after deliberate or accidental venting from underground shafts.
… some gases that escape during an underground explosion precipitate into ‘solid rain’. Krypton 90 is just one of dozens of radioactive noble gases that do transform in mid-air from gas to a solid.
… In the 30 minutes from the time it is ‘born,’ Krypton-90 gas [decays] into a solid… ‘strontium 90,’….
While many krypton and xenon gases are less radioactive than most solid-form radioactive elements, certain gases, like krypton-86, are clearly dangerous. Krypton-86 is a neutron-activator – it can turn ordinary soil, brick, flesh and air into their radioactive versions.
Long-lived krypton and xenon and argon gases, like krypton-85 and xenon-133, are all heavier than air and thus they settle near the ground (see footnote 9 ….)
… a 1995 study published in the journal Applied Radiation and Isotopes noted that ‘Calculations showed that it would take nearly 1 h [hour] to form the total cumulative yield for 137 Cs.’2 Therefore, if xenon-137 gases immediately leak or seep from underground cavities, they have a ‘travel time’ of close to an hour before they fully ‘precipitate’ out into cesium-137….”
A very informative discussion, if a little heavy on jargon and inconsistent terminology. Here’s my question: if the reactor of Fukushima Daiichi unit #1 had not been shut down completely on detection of seismic activity, would it have been able to survive the events with less risk, damage or cost?
I hate to self-promote too much on someone else’s blog… but I couldn’t sleep, so I wrote a blog post about Fukushima.
http://enochthered.wordpress.com/2011/03/13/all-right-its-time-to-stop-the-fukushima-hysteria/
Worth a detailed look (mentioned above). This looks to me like it’s the source of many of the images being used around the web to explain what’s happening:
[Magdi Ragheb, U. Illinois at Urbana-Champaign]
Note it’s copyrighted — cite your source, credit the author.
An interesting note from that document: see Fig. 17, on p.15 — the “Mark I steel containment design used in 60 percent of USA BWRs” [as of 1986] is the reactor design we’re all studying. From his Table 4:
Pre Mark I — 4
Mark I — 22 steel, 2 reinforced concrete
Mark II — 2 steel, 3 reinforced concrete, 2 post-tensioned concrete
Mark III — 2 steel, 1 reinforced concrete.
So the reactors around the US should perform as well as the ones we’ve been looking at — well beyond their design strength.
My advice to industry (grin):
Keep those batteries charged. Actively pursue adding nice, big, fields of solar plants, cogeneration, windmills, and pumped water and compressed air power storage around them — so we have multiple redundant power sources _and_ each fission plant has multiple redundant power available right in its back yard. (Then shield them against solar flares).
AND pursue getting the residential customers well equipped with solar hot water and solar photvoltaic.
When the worst happens — a solar flare takes out the utility grid for a couple of years, say — the big industrial power supply can either support keeping the reactors working for a while, or take the reactors down gracefully — and supply power from whatever source and the people at home can eke out a more or less comfortable low-power month or year until things get put back together.
“Mr Goto calculated that because Reactor No 3 at Fukushima-Daiichi – where pressure is rising and there is a risk of an explosion – used a type of fuel known as Mox, a mixture of plutonium oxide and uranium oxide, the radioactive fallout from any meltdown might be twice as bad.”
When plutonium is used as fuel e.g. in the form of MOX, the neutron spectrum becomes significantly harder than it would be if pure uranium were used. Consequently the effect of neutron absorbers such as boron, xenon and control rods becomes proportionately less i.e. there will be less absorption than if the reactor were fuelled with uranium and the neutron spectrum were softer.
In addition to the above, the moderator temperature coefficient around MOX fuel tends to be less than it would be for uranium fuel. Consequently the self-limitation of the core becoming less reactive the more the moderator temperature increases will be reduced. This is relevant because in an accident the moderator (water in the case of Fukushima) gets hotter and this temperature rise diminishes the thermalising of the neutrons and therefore dimishes the reactivity of the core. Of course, most of the heat in a tripped reactor is simply the decay heat generated by fission products, but there will still be SOME neutrons created by on-going fission even if they are only the product of spontaneous neutron emission, so it’s good if those neutrons are not thermalised and thus have a better chance of not causing further fissions.
Lastly the Doppler temperature coefficient is lower in a MOX fuelled core than in a pure uranium core. Just as the moderator temperature coefficient affects the spectrum of the neutrons reaching the fuel, the DTC affects the absorption cross-section of the fuel itself, and thus affects whether a given neutron will be captured and cause a fission.
All in all, MOX fuelled reactors have less “buffer” in the way they react to temperature changes and, compared to uranium fuelled reactors, require a bit more in the way of absorbers and poisons to keep them under control. In theory this shouldn’t be a problem because a MOX fuelled core will have been designed specifically for the MOX fuel. In practice, though, when adapting an original uranium design to a MOX design some compromises undoubtedly have to be made because the basics of the core e.g. the pressure vessel dimensions can’t be re-optimised. As a consequence there might be a bit of a reduction in the safety margin when using MOX fuel in a reactor design that was originally intended for uranium.
On top of everything else, a huge amount of experience and literature exists for uranium fuelled designs and accidents, whereas for MOX fuel there is less knowledge and experience. As a result it is easier to imagine a miscalculation or error of judgement when dealing with MOX emergencies.
Having said all the above, I have confidence in the abilities of the Japanese nuclear engineers, and (standing on my personal soapbox) if I was in the region I’d be more worried about the toxic effects of smoke from refinery fires, water-borne diseases, and straightforward exposure and hypothermia because of loss of electricity production than I would about whether MOX makes another accident more or less likely.
Are they real hazards surrounding the MOX fuel in that reactor, or is it just irrational plutonium phobia?
IAEA update on Onagawa: http://on.fb.me/gM23j7
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Red_Blue, as far as I understand it, the neutrons are basically irrelevant, since criticality stopped when the reactors automatically shut down at the quake.
Which brings me to another topic – was there any opportunity to keep the reactors running? The main argument against this would be that the grid was down, but both Fukushima sites are multiple reactor – perhaps one could’ve kept running to supply house loads?
Reality is bad enough.
http://www.nytimes.com/2011/03/14/world/asia/14nuclear.html?hp
Partial Meltdowns Presumed at Crippled Reactors
By HIROKO TABUCHI and MATTHEW L. WALD
“Officials thought partial meltdowns had occurred at two reactors and were bracing for a second explosion, even as problems were reported at two more nuclear plants….
…
… The emergency at the hardest hit plant, Fukushima Daiichi Nuclear Power Station, appeared to be the worst involving a nuclear plant since the Chernobyl disaster 25 years ago, and at least 22 residents near the plant showed signs of radiation exposure, according to local officials. The crisis at that plant, which is much further from Tokyo, continued late Sunday.
A day after an explosion at one reactor there, Japanese nuclear officials said Sunday that operators at the plant had suffered a setback trying to bring the second reactor thought to be in partial meltdown there under control. The operators need to inject water to help cool the reactor and keep it from proceeding to a full meltdown, but a valve malfunctioned on Sunday, hampering their efforts for much of the day.
Pressure at the reactor rose during the delay, leading to increased worries of an explosion. At a late-night press conference, officials at Tokyo Electric Power Co., which runs the plant, said the valve had been fixed, but said water levels had not yet begun rising.
Until late Sunday, the government had declared an emergency at only two nuclear plants, Daiichi and the nearby Fukushima Daini.
Then, the International Atomic Energy Agency announced that Japan had added a third to the list because radiation had been detected outside the plant, which is about 60 miles from Sendai, a city of 1 million people in Japan’s northeast. The government did not immediately confirm the report from the I.A.E.A., which said it was not yet clear what caused the release of radiation.
Soon after that announcement, Kyodo News reported that a plant about 75 miles north of Tokyo was having cooling system problems….”
So the NYT is behind on this news as Barry Brooks posted earlier here — the alarm at Sendai was apparently detecting the releases from the other plants (the winds have been light and variable, apparently).
Note that the detectors used are _very_ sensitive, likely being done by pulling air through a very fine filter for a long period of time then checking that for radioactivity.
Anyone who has used a Geiger counter on their laundry dryer lint knows how this procedure concentrates and increases the natural radioactivity, and it would do the same with anything artificial — and the kind of radiation detected would help identify the source.
_______
This appears to be the Kyodo News item, I’m guessing: http://english.kyodonews.jp/news/2011/03/77484.html
Cooling system pump stops at Tokai nuclear power plant 14 Mar 2011 1:55
One of the two cooling system pumps at the Tokai No. 2 nuclear power plant in the village of Tokai, Ibaraki Prefecture, stopped Friday when a massive earthquake hit Japan but there is no problem with cooling as the remaining pump is working, according to local authorities late Sunday.
> was there any opportunity to keep the reactors
> running? … the grid was down, but both Fukushima
> sites are multiple reactor – perhaps one could’ve
> kept running to supply house loads?
No, because the grid is the reliable source; all the others are subject to problems, as we’ve seen. Once the grid is gone, there _should_ have been enough power sources and equipment to handle the steps involved in carefully shutting down, and then actively cooling, the plants. Nobody would throw away any of that safety margin by keeping a fission pile operating, without the grid being available.
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
It’s kind of waste to continue posting here.
@Nikkei Don’t let the door hit you in the ass on they way out.
From reading the various (good) accounts so far, it appears the initial shutdown was automatic.
Do we know if there was any actual damage caused by the earthquake, to the main systems or cooling systems?
After that shutdown, and before any of the other failures, would it have been possible to restart the reactor, to remove the dependency on the diesel and battery power for running the cooling systems?
At what point did they lose the ability to restart?
(There might not be enough information available yet, but it is something that I think would have been wise to consider, at least with 20/20 hindsight.)
Brian
Good clarification here:
http://www.chicagotribune.com/news/nationworld/la-sci-japan-quake-reactor-qa-20110314,0,7463052.story
“Japanese authorities say there has been a partial meltdown. What does that mean?
That statement is based on the detection of extremely small quantities of the isotopes cesium-137 and iodine-131 in the environment near the plant. Those two elements are byproducts of uranium fission. During the normal operation of a reactor, cesium-137 and iodine-131 migrate to the gap between the fuel pellets and the zirconium cladding. The fact that some quantities escaped into the environment suggests the cladding heated up and cracked to some degree. That does not mean any fuel has melted, although it is possible that a small amount did. Barring a major catastrophe, no one will know whether fuel has melted until they can get into the containment vessel and examine it.
…
Most likely, the company would keep pumping seawater through it for several years until it had cooled down sufficiently and many of the radioactive isotopes had decayed enough that engineers could go in and remove the fuel. That, in essence, is what happened in 1979 in the partial core meltdown at the Three Mile Island Generating Station in Pennsylvania. “
> would it have been possible to restart the reactor
Remembering I’m a pure amateur reader here, you can find better answers from Google (grin):
Any sudden shutdown has to be followed by a careful recovery, it’s not like turning off a light switch; a whole lot keeps changing for a while.
“When Enrico Fermi fired up the first nuclear reactor at Hanford in 1944, he was in for quite a surprise. Shortly after the reactor went critical, power stalled and the reactor shut down. A few hours later, the reactor unexpectedly started up again all by itself….”
http://nuclearfissionary.com/2010/05/06/nuclear-fission-for-dummies-xenon-135/
Read that for a bit about what happened to Fermi and how things are changing in a fission reactor.
This sort of thing takes serious study. The behavior changes over time and that has to be very well understood to bring it to a stable well understood configuration before starting the reaction up again.
Here for example from coursework
http://www.nuceng.ca/br_space/class/Module3D_XenonJun21.pdf
“the large and rapid build-up of additional Xenon reactivity load following a reactor trip can cause an extended (approximately 40 hours) of reactor shutdown …”
Psst, Barry, get the T-shirt: http://nuclearfissionary.com/wp-content/uploads/2011/01/stewart-brand.jpg
Hank, I’ve seen proposals that nuclear plants could be designed to keep running in the event of loss of external grid power – to act as points from which the grid can be restarted, in fact. Not necessarily an easy task but one worth doing I’d think.However clearly for such an exacting infrastructure role there should be some reward to a commercial operator also, in the context of the US system at least.
We rely upon advanced technology to provide us the productivity based benefits that are the basis of our lifestyle and compensation system.
All forms of advanced technology carry with them risks. To pretend otherwise is foolish.
If we want risk free lives then we must give up the benefits that come from technological advances in quality of life and productivity.
We have over 100 nuclear power plants in the USA, and none of them has had an issue since Three Mile Island.
There is no free lunch. If we want to continue to advance as a society, and compete with less technologically advanced societies who have more people but less technology than we do (India, China), then we need to continue to take managed technological risks.
For us to turn our back on nuclear power when it is the only source of carbon free and affordable power, because of politically correct scare-mongering would be a travesty.
Anyone interested in the nitty-gritty of nuclear power should look up http://www.phy6.org/stargaze/Snuclear.htm
and the 6-site course (complete with problems!) linked there. For a wider sweep of physic s and space, follow links in http://www.phy6.org/readfirst.htm
Joffan,
At Daiichi they cannot immediately restart the 3 reactors that were tripped… but perhaps they could consider one of the three which were shut down for maintenace for back-up duties as you suggest… if any one of them are near ready for restart.
http://www.reuters.com/article/2011/03/13/us-japan-quake-experts-idUSTRE72C2M020110313?pageNumber=3
“The problem is that worldwide there are lots of operating reactors built in early 1970′s. I think that (after this catastrophe) the oldest plants will simply be closed and new compensatory ones will be built, unless political situation turns dramatically and nothing gets built.”
“In the United States, there are 100 plants, and half of those are built in 1970′s” …”
—-
TEPCO’s website is very, very slow; here’s a chunk from the last press release:
Press Release (Mar 13,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 9pm March 13th)
“- We are currently coordinating with the relevant authorities and departments as to how to secure the cooling water to cool down the water in the spent nuclear fuel pool.”
————-
http://www.zerohedge.com/article/iaea-refutes-reactor-3-cooling-problems-provdes-fukushima-status-update?page=1
IAEA Refutes Reactor 3 Cooling Problems, Provides Fukushima Status Update; Credibility Schism Developing In Japan
03/12/2011 20:56 -0500
Contrary to earlier reports that cooling at Reactor 3 at Fukushima has failed (as per CNN and Reuters) and there is now a state of emergency for three reactors at the site, the IAEA has released a report refuting these rumors. It appears that there is a split in news reporting in Japan: on one hand we have the Nuclear and Industrial Safety Agency which seems to present a downside case, while the government is obviously spinning news in a favorable direction….”
——-
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
Japan Earthquake Update (14 March 2011 01:30 CET)
Based on information provided by Japanese authorities, the IAEA can confirm the following information about the status of Units 1, 2 and 3 at Fukushima Daiichi nuclear power plant.
Unit 1 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently no power via off-site power supply or backup diesel generators being provided to the plant. Seawater and boron are being injected into the reactor vessel to cool the reactor. Due to the explosion on 12 March, the containment building has been lost.
Unit 2 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently neither off-site power supply nor backup diesel generators providing power to the plant. The reactor core is being cooled through reactor core isolation cooling, a procedure used to remove heat from the core. The current reactor water level is lower than normal but remains steady. The containment building is intact at Unit 2.
Unit 3 does not have off-site power supply nor backup diesel generators providing power to the plant. As the high pressure injection system and other attempts to cool the reactor core have failed, injection of water and boron into the reactor vessel has commenced. Water levels inside the reactor vessel increased steadily for a certain amount of time but readings indicating the water level inside the pressure vessel are no longer showing an increase. The reason behind this is unknown at this point in time. To relieve pressure, venting of the containment started on 13 March at 9:20AM local Japan time. Planning is underway to reduce the concentration of hydrogen inside the containment building. The containment building is intact at Unit 3.
The IAEA is seeking information about the status of spent fuel at the Daiichi plant.
http://www.ucimc.org/content/meltdowns-grow-more-likely-fukushima-reactors
by Robert Alvarez
“Robert Alvarez, an Institute for Policy Studies senior scholar, served as senior policy adviser to the Energy Department’s secretary and deputy assistant secretary for national security and the environment from 1993 to 1999.”
“… Along with the struggle to cool the reactors is the potential danger from an inability to cool Fukushima’s spent nuclear fuel pools. They contain very large concentrations of radioactivity, can catch fire, and are in much more vulnerable buildings. The ponds, typically rectangular basins about 40 feet deep, are made of reinforced concrete walls four to five feet thick lined with stainless steel.
The boiling-water reactors at Fukushima — 40 years old and designed by General Electric — have spent fuel pools several stories above ground adjacent to the top of the reactor. The hydrogen explosion may have blown off the roof covering the pool, as it’s not under containment. The pool requires water circulation to remove decay heat. If this doesn’t happen, the water will evaporate and possibly boil off. If a pool wall or support is compromised, then drainage is a concern. Once the water drops to around 5-6 feet above the assemblies, dose rates could be life-threatening near the reactor building. If significant drainage occurs, after several hours the zirconium cladding around the irradiated uranium could ignite.
Then all bets are off.
On average, spent fuel ponds hold five-to-ten times more long-lived radioactivity than a reactor core. Particularly worrisome is the large amount of cesium-137 in fuel ponds, which contain anywhere from 20 to 50 million curies of this dangerous radioactive isotope. With a half-life of 30 years, cesium-137 gives off highly penetrating radiation and is absorbed in the food chain as if it were potassium.
In comparison, the 1986 Chernobyl accident released about 40 percent of the reactor core’s 6 million curies. A 1997 report for the Nuclear Regulatory Commission (NRC) by Brookhaven National Laboratory also found that a severe pool fire could render about 188 square miles uninhabitable, cause as many as 28,000 cancer fatalities, and cost $59 billion in damage. A single spent fuel pond holds more cesium-137 than was deposited by all atmospheric nuclear weapons tests in the Northern Hemisphere combined. Earthquakes and acts of malice are considered to be the primary events that can cause a major loss of pool water.
In 2003, my colleagues and I published a study that indicated if a spent fuel pool were drained in the United States, a major release of cesium-137 from a pool fire could render an area uninhabitable greater than created by the Chernobyl accident. We recommended that spent fuel older than five years, about 75 percent of what’s in U.S. spent fuel pools, be placed in dry hardened casks — something Germany did 25 years ago. The NRC challenged our recommendation, which prompted Congress to request a review of this controversy by the National Academy of Sciences. In 2004, the Academy reported that a “partially or completely drained a spent fuel pool could lead to a propagating zirconium cladding fire and release large quantities of radioactive materials to the environment.”
This may be the study referred to:
http://cipi.com/PDF/beyea2004%20spent%20fuel%20addendum.pdf.
Here is the Alvarez study:
http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf
[…] And, well, of course, the nukers themselves want us all to believe it’s all hunky-dory. […]
[…] http://atomicinsights.blogspot.com/2011/03/sowing-calm-in-face-of-focused-campaign.html […]
Good brief discussion here:
http://boards.straightdope.com/sdmb/showthread.php?t=600501
Several people commenting gave a variety of links there:
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0933/sec3/082r3.html
Resolution of Generic Safety Issues: Issue 82: Beyond Design Basis Accidents in Spent Fuel Pools (Rev. 3) (NUREG-0933, Main Report with Supplements 1–33)
http://www.nap.edu/openbook.php?record_id=11263&page=38
Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report (2006)
Board on Radioactive Waste Management (BRWM)
http://spectrum.ieee.org/energywise/energy/nuclear/japan-nuclear-accident-worse-than-worst-again
Japan Nuclear Accident: Worse than Worst, Again
Bill Sweet / Sat, March 12, 2011
http://www.cfr.org/weapons-of-mass-destruction/nuclear-spent-fuel-pools-secure/p8967
Are Nuclear Spent Fuel Pools Secure?
Speaker: Kevin Crowley
June 7, 2005, Council on Foreign Relations
em1ss, sodium has not been abandoned as a coolant for power generating plants. It looks like the best choice for fast reactors. Check this out:
http://www.ne.doe.gov/pdfFiles/SodiumCoolant_NRCpresentation.pdf
And from wikipedia: “The fast reactors offer the possibility of burning actinides to further reduce waste and of being able to breed more fuel than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance and physical protection.”
Sorry for slightly off-topic content… but to me, the take-home message of Fukushima is: we need to bring next-generation plants online quickly. The older designs are problematic.
Plenty of information on sodium-cooled fast reactors on this very site. Start here:
http://bravenewclimate.com/category/ifr-fad/
Hank:
did you read the ieee piece? Do you know much about them (ieee)?
here’s a sample:
“Operators also are injecting boron into the reactor vessel to head off a re-criticality-a situation in which melting fuel reconfigures itself and starts reacting self-sustainably again.”
“recriticality”?
The article also proclaimed the accident second worst ever.
Recriticality would require a chain reaction, not an increase in decay heat due to lack of coolant.
am I mistaken here, or is this guy purposefully conflating LOCA and criticality incidents? I have seen this over and over.
Barry: this is absolutely maddening. Unless I am missing something.
DV: what’s your view of Hank’s sources up above me?
I’m no expert… just an interested observer…
“recriticality” – I think the chain of events meant to be described is:
(1) Loss of cooling ability (e.g. loss of coolant)
(2) Uncontrolled heating of the core
(3) Melting fuel rods
(4) Molten fuel in the fuel rod tubes filling spaces, reaching higher densities, and thus levels of free neutrons (from spontaneous fission) than can be managed via control rods alone (i.e. reaching criticality)
Adding boron, aka “liquid control rods” into the cooling spaces, gives an extra margin of avoiding criticality even if fuel rods melt (a bit?).
That’s my uneducated take on the meaning of the term, in the context of the article.
Gregory Meyerson, – they seem legitimate, but I haven’t looked at the content in detail. However it does look like these are mostly opinions, and as such must be weighed by who is holding them, rather than the venue in which they reside.
[…] internet and media right now about the Fukushima nuclear reactor situation. In my previous post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, as […]
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Just want some “lay-person, oil industry controls engineer” clarification on Fukushima Daiichi No 1 …
My understanding is that secondary containment in a 1970s GE BWR-1 (outwith the RPV) is the concrete “dry well”.
I’m more than curious if the H2 explosion at No 1 was within the dry well with all its exposed controls / valves / torus supression pool (scary) and “blew the lid” … or just a superficial blast in the service housing above, which looks more probable looking at photos ?
But how did hydrogen leak or release there … thought venting was within the turbine hall … no obvious stack that I can see …
We need facts to counter the s**t even the BBC are putting out, “charlatan engineers” who want to see the death of the only power source that can see civilisation survive post-oil !
Also what about the pools for the spent fuel rods, now seemingly exposed to the environment, is the boraic acid cover still OK ?
Why are we not getting this info ?
> recriticality
That’s not from the heat of radioactive decay, remember. Criticality means slow neutrons hit fissionable atoms and so cause enough additional fission events to produce a slightly larger number of slow neutrons, which produce more fission events. Those kinds of accidents have happened in many ways.
They’re adding water to the core; water slows fast neutrons down. If the core fell apart, leaving a pile of fuel rods at the bottom of the container-criticality could happen in that situation. So they’re adding boron, which soaks up neutrons.
They don’t know what’s happening inside these bottles. So they’re adding boron just in case.
—-
And Reactor 3 has had an explosion. Not much info yet.
http://www.world-nuclear-news.org/RS_Explosion_rocks_third_Fukushima_reactor_1402111.html
14 March 2011
First published: 3.08am GMT
… this time at the third reactor unit. Initial analysis is that the containment structure remains intact.
… water injection operations have continued and pressure readings from the reactor system remained within a comfortable range. ….Seawater was being injected into the reactor vessel and levels had initially risen as expected. However, a gauge indicated that the rise had tailed off, despite ongoing seawater injection.
The gauge in question indicated that water levels are around two metres below the top of the nuclear fuel assemblies, which would represent a very serious situation with the risk of fuel damage….”
For laura-eva — look back a ways in this thread and you’ll find the explanation you’re asking for; search “secondary containment” will find it. This picture shows the location of the explosion at Reactor 1 — up above the massive concrete structure http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
http://www.boingboing.net/2011/03/13/explostion-at-fukush.html — video
“This apparent hydrogen blast involved the plant’s troubled No. 3 reactor. A similar explosion happened at the No.1 reactor at the same plant on Saturday. Both blasts tore the roof off of the affected structure, but are believed not to have damaged the reactor core.”
DOH … reaction has been poisoned (verified on all reactors) … how does adding water as a supposed moderator make something dead come alive ?
Adding water will never restart a reaction with virtually nil neutron flux …
I’m an engineer and understand how you would build a reactor, understand negative coefficient design, the use of control material.
Hopefully the compromised fuel / control assembiles will be extracted at some point, and the sites rebuilt with most reactors up and running within the year ?
Its not an option, its the way that most countries have to look for their power in a world of dwindling oil ???
At this point I wonder why they haven’t taken off some of those upper deck side panels and let the air blow through there, so hydrogen can’t accumulate.
It would be a tradeoff — it would defeat the described “secondary containment” function (assuming they do have fans running and negative air pressure throughout the building.
If the negative pressure fans are running they’re presumably pushing the exhaust air through the standard filter system. But do they even have enough electric power for that system to operate, anyone know? If it’s not operating, taking a few sheets of sheet metal off the upper walls for ventilation wouldn’t lose any protection and could let hydrogen escape.
More amateur speculation on my part, nothing more.
Spent fuel rods in No 1 … pool now open to the elements … anybody ?
laura_eva, again, look back in the thread, there are diagrams of the location; the pool is a very deep hole in the concrete; the sketches show where the spent fuel is located, down under 20 feet of water, alongside the top of the reactor vessel, below the big orange crane.
What blew off the top is sheet metal — leaving the framework behind. Yes, it’s a concern. Several press releases quoted above mention the issue — they need to have water circulating in the spent fuel pool and be adding water as needed to keep the level up.
But losing some sheet metal over the top isn’t going to mess that process up too badly, compared to the other issues.
It does mean whatever negative pressure system they were using to draw air in and filter it is gone, so they’re relying on the big concrete primary containment now and on the steel bottle inside that, but they were already venting steam and so not really containing much with that sheet metal roof.
Or so I’d guess. I’m just another blog reader. But seriously, do look back, there is a lot of good info and most questions have been asked and answered so far earlier in the past three days.
http://i1107.photobucket.com/albums/h384/reactor1/BoilingWaterReactorDesign_3.jpg
see discussion earlier.
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Whoah, this is alarmingly wrong:
> laura_eva, on 14 March 2011 at 3:23 PM said:
> DOH … reaction has been poisoned (verified
> on all reactors) … how does adding water as a
> supposed moderator make something dead
> come alive ?
>
> Adding water will never restart a reaction with
> virtually nil neutron flux …
>
> I’m an engineer …
Maybe. Maybe not. Citations needed for factual claims.
Try looking: http://www.google.com/search?q=Criticality+Safety+in+the+Waste+Management+of+Spent+Fuel
From the first hit:
“Criticality Safety in the Waste Management of Spent Fuel from NPPs
Robert Kilger
Abstract:
During irradiation in the reactor core, fissile material from nuclear fuel is depleted for power generation. However, significant amounts of fissile nuclides, mainly 235U and 239Pu, are still present in spent fuel unloaded from the core, with the inherent potential for maintaining an inadvertent nuclear chain reaction under unfavorable conditions. Due to this reason, criticality safety has to be demonstrated for all stages of waste management of spent nuclear fuel. This pertains e.g. to wet storage in cooling ponds, dry storage and transport of the fuel in casks, dissolver stages in reprocessing plants, as well as the direct final disposition of the spent fuel. Usually, for system design the reactivity of the spent fuel has been considered as being equal to fresh fuel…..”
[…] • http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ • […]
From the engineers, for the engineers:
———————-
http://www.bazley.net/institute/archives/archives.html
———————-
What Is a Crit Engineer and What Is Criticality Safety?
Trying to Find Short Definitions for the Practitioner and Layman
After experiencing the holidays and having to answer a few more questions from friends and relatives about what we, as nuclear criticality safety engineers, do, the Institute has started work on generating a few web pages to explain to the layman (“—or woman” to quote Life of Brian) what criticality safety is and what a criticality safety engineer does. Along this endeavor, we started looking for some short definitions of who we are and what we do.
Of course, we stumbled upon the classic definitions of some individuals of the criticality safety community. But those definitions were lacking in perspective of what our jobs as engineers were. We could only find one simple definition of what a criticality safety engineer is.
The short definitions are provided below in hopes that a few of you would provide us with some more insight (and hopefully some of your artistic prose) into other or more meaningful definitions of criticality safety and criticality safety engineering. (And would also provide us with any already existing celebrity definitions missed.) We’ll add your definition to our list giving you the appropriate credit. Thanks for your help!
Definitions of Criticality Safety
Protection against the consequences of an inadvertent nuclear chain reaction, preferably by prevention of the reaction. — ANSI/ANS-8.1-1998
The art of avoiding a nuclear excursion. — Hugh Paxton
The art and science of not building a nuclear reactor without shielding, coolant, and control — Francis Alcorn
Definitions of a Criticality Safety Engineer
One who, typically by trial and error, realizes that one can not intuitively predict the change in reactivity by any change in any nuclear parameter. — Chris Miller
———————————————-
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
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[…] http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ • http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/ var […]
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] internet and media right now about the Fukushima nuclear reactor situation. In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, […]
[…] • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html• http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/• […]
Interesting night it seems. Another Hydrogen explosion at Unit 3. Buried in these posts is something I forgot about. Hydrogen injection to Feedwater for Hydrogen Water Chemistry.
Alot of BWRs have implemented this to minimize O2 in the vessel and corrosion. This system should shutdown automatically on a scram by most designs. Possibly this is part of the equation for buildup of H2 in the Reactor Buildings.
The discussion about the spent fuel pools backs up that a loss of level will result in significantly increased radiation dose rates as the water level drops.
Continue to monitor reports for this significant increase in radiation levels near the Reactor Buildings and on Site. Otherwise it is safe to assume spent fuel pool level is ok or being maintained adequately above the spent fuel.
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em1ss, we are discussing the issue of hydrogen injection to the feedwater here: http://wp.me/piCIJ-12u
Laura, with regards to Spent Fuel Pool exposure. The surface of the pool is normally exposed to the refueling floor, which is the top of the Reactor Building. With panels blown off and Roof sections of the top floor of the building the surface of the pool is exposed to the environment.
As long as they keep water in the pool, radiation levels and spent fuel damage will not occur thermally. As described in other posts last night the pool it self is quite a robust concrete walled structure with a steel liner.
However who knows what fell into the pool and may have caused some damage to the fuel assemblies stored there. Based on reported rad levels and airborne activities it doesn’t seem like this type of damage has occurred as of yet nor a loss of pool water level of significance.
Thanks Barry, will check back later its off work for now.
Somewhere, the anti-nuclearists actually sit around and they actually make up this crap completely out of thin air. They seem to just pick an element at random, and pick a mass number at random (and not check the table of nuclides to see if it actually exists, or if it’s a stable isotope) and they say that this is the deadly radioactive evil that’s being spewed from the reactor.
Kr-86 is a stable (non-radioactive) nuclide, which comprises 17% of natural krypton.
i would like to know, if the heat is great enough, in conjuction with the zirconium as an catalyst, to split the water into hydrogen and oxygen, which the zirconium reacts with the oxygen and are left with just the hydrogen as a free gas, when seawater is being used does it also split the NaCl in the seawater producing Clorine gas as well, and if so what type of additional danger could that pose?
[…] • http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ • http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/ ALL, […]
Third nuclear reactor failing in Japan!
http://news.yahoo.com/s/ap/ap_on_bi_ge/as_japan_earthquake_nuclear_crisis
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[…] culpable reporting. Here is a link with some good explanations. That links not working for me. Here’s one I have Cheers Michael __________________ My updated photo […]
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[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] the internet and media right now about the Fukushima nuclear reactor situation. In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, […]
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[…] Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (brave new climate) […]
Are they still having problems with off site electricity?? Should bring in a larger ship to the site to provide plenty off power.
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[…] Discussion thread at Brave New Climate […]
Hallo ,
what do you think about the explosion in fukushima 1/block 3 ?
Dont you think it look much more serius than 1/block 1?
Greatings
Thomas
Solution to buy time
-Fill the steel containing vessel with wet sand it will act as a temporary ceramic insulation.
Prof. Von Lampa
[…] var zoomImagesBase = ‘/wp-content/plugins/wp-fancyzoom/’; addDOMLoadEvent(setupZoom); .wp-polls .pollbar { margin: 1px; font-size: 6px; line-height: 8px; height: 8px; background-image: url(‘http://me.beiwo.me/wp-content/plugins/wp-polls/images/default/pollbg.gif'); border: 1px solid #c8c8c8; } /* */ jQuery.ajax({type:’GET’,url:’http://me.beiwo.me/wp-content/plugins/wp-postviews/wp-postviews.php',data:’postviews_id=2583′,cache:false});/* */ RSS Feeds Register Log inDJMAX手机被窝留言板被窝图集网站首页欢欢翻唱转载文章雨蕉音乐分享动漫日语Mar140评论 0 顶 【转载/科普】为什么我不担心日本的核电站 布栩咚。 转载文章 0次浏览本文转自：http://songshuhui.net/51583.html 文章内容仅供参考， 本文尚无任何权威性暗示。以下为转载内容全文……编者按：非常感谢V2EX的译者Livid授权松鼠会转载此文，这篇文章的原作者MIT 的研究科学家 Josef Oehmen 博士仍在更新，译文也会随之更新。原作：Josef Oehmen V2EX译者：Livid 我在这里写下这些文字，是为了让大家对在日本发生的事情——核反应堆的安全问题，感到放心。事态确实严重，但是已经在控制范围内。这篇东西很长！但是你读完之后，你会比世界上任何记者都明白核反应堆究竟是怎么回事。核泄漏确实已经发生，但是在将来不会有任何显著的泄露。“显著泄露”大概会是个什么程度？打个比方说，可能比你乘坐一趟长途飞行，或是喝下一杯产自本身具有高程度自然辐射地区的啤酒，所受到的辐射要多一些。我读了自从地震发生以来的所有新闻报道。可以说几乎没有一篇是准确或是无误的（当然也可能是因为地震发生之后在日本的通讯问题）。关于“没有一篇是无误的” 我并不是指那些带有反核立场的采访，毕竟这在现在也挺常见的。我指的是其中大量的关于物理和自然规律的错误，及大量对于事实的错误解读——可能是因为写稿子的人本身并不了解核反应堆是如何建造和运营的。我读过一篇来自 CNN 的三页长度的报道，每一个段落都至少包含一个错误。接下来我们会告诉大家一些关于核反应堆的基本原理，然后解释目前正在发生的是什么。福岛核电站的反应堆属于“沸水反应堆”（Boiling Water Reactors），缩写 BWR。沸水反应堆和我们平时用的蒸汽压力锅类似。核燃料对水进行加热，水沸腾后汽化，然后蒸汽驱动汽轮机产生电流，然后蒸汽冷却后再次回到液态，然后再把这些水送回核燃料处进行加热。蒸汽压力锅内的温度通常大约是 250 摄氏度。上文提到的核燃料就是氧化铀。氧化铀是一种熔点在 3000 摄氏度的陶瓷体。燃料被制作成小圆柱（想像一下就像乐高积木尺寸的小圆柱）。这些小圆柱被放入一个用锆锡合金（熔点 2200 摄氏度）制成的长桶，然后密封起来。这就是一个燃料棒（fuel rod）。然后这些燃料棒被放到一起组合为一个更大的单元，然后这些燃料单元被放入反应堆内。所有的这些，就是一个核反应堆核心（core）的内容。锆锡合金外壳是第一层护罩，用来将具有放射性的核燃料与世隔绝。然后核心被放入“压力容器”中，也就是我们之前提到的蒸汽压力锅的比喻。压力容器是第二层护罩。这是一个坚固结识的大锅，设计用于容纳一个温度可能达到数百摄氏度的核心。在核心降温措施恢复前，压力容器起到一定的保护作用。一个核反应堆的所有的这些“硬件”——压力容器，各种管道，泵，冷却水，然后被封装到第三层护罩中。第三层护罩是一个完全密封的，用最坚固的钢和混凝土制成的非常厚的球体。第三层护罩的设计，建造和测试只是为了一个目的：当核心完全熔融时，将其包裹在其中。为了实现这个目的，在压力容器（第二层护罩）的下方，铸造了一个非常巨大厚实的混凝土大碗，这一切都在第三层护罩的内部。这样的设计就像是为了“抓住核心”。如果核心熔融，压力容器爆裂（并且也最终融化的话），这个大碗就可以装下融化了的燃料及其他一切。这个大碗设计成让融化的燃料能够向四周铺开，从而实现散热。在第三层护罩的周围包裹的是反应堆厂房。反应堆厂房是一个将各种风吹雨打挡住的外壳。（这也是在爆炸中被毁坏的部分，我们稍后再说）福岛第一核电站一号机确实是通用电气的Mark I型沸水堆。新闻里露出钢筋的部分是最外部的厂房，里面的安全壳应该没事。——@铁公鸡zq核反应的一些基本原理铀燃料通过核分裂产生热量。大的铀原子分裂成更小的原子，这样就产生热量及中子（构成原子的一种粒子）。当中子撞击另外一个铀原子时，就触发分裂，产生更多的中子并一直继续下去。这就是核裂变的链式反应。而现在的情况时，当一堆燃料棒凑在一起时就会很快导致过热，然后在 45 分钟后就会导致燃料棒融化。但是值得指出的是，在核反应堆内的燃料棒是绝对不可能导致像原子弹那样的核爆炸的。制造一颗原子弹实际上是相当困难的（不信你们可以去问问伊朗）。当年切尔诺贝利的情况是，爆炸是由于大量的压力积攒，氢气爆炸然后摧毁了所有的护罩，然后将大量的融化的核心挥洒到了外界（就像一颗 “脏弹”）。这样的情况为什么在日本没有发生，及为什么不会发生，请继续看下面。为了控制链式反应的发生，反应堆操作员会用到“控制棒”。控制棒可以吸收中子，从而瞬间停止链式反应。一个核反应堆是这样设计的：当一切正常运转时，所有的控制棒是不会用到的。冷却水会在核心产生热量的同时带走热量（并转化为蒸汽和电力），并且在常规的 250 摄氏度的运转温度下还有许多余地。而挑战在于将控制棒插入并停止链式反应后，核心依然在产生热量。虽然铀元素的链式反应已经停止，但是在铀元素的核裂变过程中会产生一些具有放射性的副产品，比如铯和碘同位素，这些元素的放射性同位素会最终衰变为更小的原子，然后失去放射性。在这些元素的衰变过程中，也会产生热量。因为它们不会再从铀元素中产生（在控制棒插入之后铀元素就停止衰变了），所以它们的数量会越来越少，然后在衰变结束的过程中，大约几天时间内，核心就会最终冷却下来。目前让人头痛的就是这些余热。核反应堆内的第一类放射性物质就是燃料棒中的铀元素，及放射性副产物铯和碘同位素。这些物质都在燃料棒内部。而除此之外，还存在第二类放射性物质，产生于燃料棒外部。而首先需要说明的是，这些外部的放射性物质的半衰期都非常短，这意味着它们会在很短的时间内衰变为没有放射性的物质。“很短”的意思就是几秒。所以即使这类放射性物质被释放到自然环境中，他们也是毫无危害的。为什么呢？因为大约就你在读完“R-A- D-I-O-N-U-C-L-I-D-E”的这几秒内，这类物质就衰变到完全不具有放射性了。这类放射性物质就是氮-16（N-16），也就是氮气（构成大气的气体之一）的具有放射性的同位素。另外就是一些稀有气体比如氩。但是这些物质是如何产生的呢？当铀原子裂变时，会产生一个中子。大部分的这些中子都会撞击到其他的铀原子由此链式反应就一直持续发生。但是其中的一些会离开燃料棒并撞击到水分子，或是冷却水中的空气。然后，一个不具有放射性的元素就会 “捕获”这个中子，并变得有放射性。而就如前文所述，在数秒内它就会衰变到它本来的面目。上面所描述第二类的放射性物质在我们接下来要讨论的核泄露中非常重要。福岛到底发生了什么接下来我会试着去总结目前的主要事实。冲击核电站的地震的威力是核电站设计时所能承受的威力的五倍（里氏震级之间的放大倍数是对数关系，所以 8.9 级地震的威力是 8.2 级，即核电站的设计抗震威力的 5 倍，而不是 0.7 的差异）。所以我们首先为日本的工程技术水平喝彩，至少一切目前是保下来了。当 8.9 级地震冲击核电站时，所有的反应堆就自动关闭了。在地震开始后的数秒内，控制棒就插入到了核心内，链式反应即刻中止。而此时，冷却系统就开始带走余热。这些余热相当于反应堆正常运转时产生的 3% 的热量。地震摧毁了核反应堆的外部电力供应。而这是核反应堆能够遇到的最严重的故障之一，因此，在设计核反应堆的备用系统时，“电站停电”是一种被高度关注的可能性。因为核反应堆的冷却泵需要电力以维持运转。而反应堆关闭后，核电站本身就不能产生任何电力。在地震发生后的一小时内一切情况是平稳的。为紧急情况而准备的多组柴油发电机中的一组启动，为冷却泵提供了所需的电力。然后海啸来了，比核电站设计时所预料的规模要更巨大的海啸，摧毁了所有的柴油发电机组。在设计核电站时，工程师们所遵循的一个哲学就是“纵深防御”。这意味着你首先需要为了你能够想象到最灾难的情况设计防卫措施，然后为了你觉得可能绝对不会发生的子系统故障设计方案，以确保即使这样的可能绝对不会发生的故障发生后，核电站依然可以安全。而一场巨大的摧毁所有柴油发电机组的海啸就是这样的一种极端情况。而所有的防卫的底线就是前面提到过的第三层护罩，将一切可能发生的最糟糕情况——控制棒插入或者未插入，核心融化或者未融化——容纳于其中。当柴油发电机组被冲走后，反应堆操作员将反应堆切换到使用紧急电池。这些电池被设计为备用方案的备用方案，用于提供给冷却系统 8 个小时所需的电力，并且也确实完成了任务。而在这 8 个小时内，需要为反应堆找到另外一种供电措施。当地的输电网络已经被地震摧毁。柴油发电机组也已经被海啸冲走。所以最后通过卡车运来了移动式柴油发电机。整个事件从这一刻起开始变得糟糕。运来的柴油发电机无法连接到电站（因为接口不兼容）。所以当电池耗尽后，余热就无法再被带走。在这个点上反应堆操作员开始按照“冷却失灵”的紧急预案进行处理。这是“纵深防御”中的更进一层。理论上供电系统不至于彻底失效，但是现实如此，所以操作员们只能退到“纵深防御”中更进一层。这一切，无论对我们看起来多么不可思议，但却是反应堆操作员的培训的一部分——从日常运营到控制一个要融化的核心。于是在这个时候外界开始谈论可能发生的核心熔融。因为到了最后，如果冷却系统无法恢复，核心就一定会融化（在几个小时或是几天内），然后最后一层防线——第三层护罩及护罩内的大碗，就将经受考验。但是此时最重要的任务是在核心持续升温时控制住，并且确保第一层护罩（燃料棒的锆锡合金外壳），及第二层护罩（压力容器）能够保持完整并尽可能多工作一段时间，从而让工程师们能够有足够的时间修好冷却系统。既然让核心冷却是那么重要的事情，因此反应堆内实际上有多个冷却系统（反应堆给水清洁系统，衰变降温系统，反应堆核心隔离冷却系统，备用水冷系统，及紧急核心冷却系统）。而究竟哪一个失效了或是没有失效在此时无法得知。所以想像一下，一个在炉子上的压力锅，持续地，慢慢地在进行加热。操作员在采取各种手段去消除其中的热量，但是锅内的压力在持续上升。于是当务之急是保住第一层护罩（熔点为 2200 摄氏度的锆锡合金），及第二层护罩——压力容器。而为了保住第二层护罩，其中的压力就需要时不时进行释放。因为在紧急时刻进行压力释放是一件重要的事，所以反应堆共有 11 个用于释放压力的阀门。操作员开始通过时不时地旋松阀门来释放压力容器内的压力。此时压力容器内的温度是 550 摄氏度。这就是关于“辐射泄露”的报道开始的时刻。我在上文中解释了为什么释放压力的同时实际上会释放第二类放射性物质（主要是 N-16 和氩），及为什么这样做其实毫无危险。放射性氮元素和氩对于人类健康没有威胁。而就在旋松阀门的过程中，发生了爆炸。爆炸发生在第三层护罩外部，反应堆厂房内。反应堆厂房不具有隔绝放射性物质的功能。虽然目前并不清楚到底发生了什么，但是这是一个很有可能的场景：操作员决定让压力容器内的蒸汽释放到厂房内，而不是直接到厂房外部（这样可以让放射性元素有更长的时间用于衰变）。而问题在于，由于核心内的高温，水分子会分解为氧和氢——一种易爆混合气体，于是也确实在第三层护罩外爆炸了。历史上也曾发生过一次类似的爆炸，不过是在压力容器内（因为压力容器没有设计好并且操作失误），进而导致了切尔诺贝利事件。而福岛核电站不会有这样的问题。氢氧混合气体是在设计核电站时需要考虑的一个巨大问题，因此反应堆在建造时就考虑到了不能让这样的爆炸发生护罩内部。如果在护罩外部爆炸了，虽然也不是设想中的状况但是可以接受，因为即使爆炸了也不会对护罩产生影响。因此在阀门旋送时，压力得以控制。而现在的问题时，如果水在一直沸腾的话，那么水位就会持续下降。核心大概被几米深的水覆盖，使得其能够在空气中暴露前坚持几个小时或几天。而一旦没有水覆盖，那么暴露的燃料棒就会在 45 分钟后达到其 2200 摄氏度的熔点。而这样就会导致第一层护罩，燃料棒的锆锡合金外壳融化。而这样的事情正在开始发生。冷却系统无法在燃料棒开始融化前恢复运转，不过燃料棒中的核燃料此时依然是完好的，但是包裹燃料的锆锡合金外壳已经开始融化。而目前正在发生的，就是一些铯和碘同位素开始随着释放出来的蒸汽，泄露到反应堆外。最严重的问题——铀燃料，目前依然是受控的，因为氧化铀的熔点在 3000 摄氏度。目前已经确认的是，检测到有一部分铯和碘同位素随着蒸汽泄露到了大气中。这似乎是一个启动“B 计划”的信号。通过在大气中检测到的铯和碘同位素，操作员可以确认某一根燃料棒的外壳（第一层护罩）已经存在破损。“A 计划”在于恢复某个常规冷却系统。为什么这个计划失败目前并不清楚，而一种可能性是海啸冲走或是污染了所有用于冷却系统的纯净水。用于冷却系统的给水是非常纯净的，去除了所有矿物质的水。使用纯净水的原因在于：纯净水很大程度上不会被激活，因此可以保持相对无辐射。而如果是脏水，那么更容易捕获中子，进而变得更加具有放射性。这不会影响到核心——因为核心不会被冷却水影响。但是会使得操作员更难处理这些具有轻度放射性的活化水。但是“计划 A”失败了——系统无法冷却，并且也没有额外的纯净水。因此“计划 B”被启动。而这就是目前正在发生的：为了避免核心融化，操作员开始使用海水来冷却核心。我不是十分清楚，他们是用海水浸泡住压力容器（第二层护罩），还是淹住反应堆外壳（第三层护罩）。不过这个不是我们现在要讨论的。要点在于核燃料现在确实已经冷却下来了。因为链式反应早就已经停止，所以目前只有非常少量的余热在产生。已经使用了的大量冷却水可以带走这些余热。因为是注入了大量的水，所以目前核心已经无法再产生足够的热量去大幅度提升压力。并且，海水中加入了硼酸。硼酸是一种“液体控制棒”。无论在发生什么样的衰变，硼都可以捕获产生的中子并进一步加速核心的冷却。福岛核电站曾经十分接近核心融化。但是目前最坏的情况已经被避免：如果没有将海水注入，那么操作员就只能继续旋松阀门以释放压力。第三层护罩必须完全密封，以避免其中发生的核心融化泄露出任何的放射性物质，然后会经过一段等待期，等待护罩内的裂变副产品完成衰变，所有的放射性粒子会附着在护罩内壁。冷却系统最终会被恢复，融化的核心也会冷却至一个可控的温度。护罩内部会被清理。然后需要做一项棘手肮脏的事情——将融化了核心移出，将凝固了的燃料棒及燃料一块一块地装入运输装置，然后运送到核废料处理厂进行处理。根据损坏状况，核电站的这块区域需要进行修理或是彻底拆除。那么，目前留给我们的是什么呢？我的总结：• 核电站会回到安全状态并始终安全 • 日本处于第 4 级别 INES 核紧急状态：核电站内事故。这对于拥有电站的公司是件糟糕事情，对其他人来说没什么影响。 • 在释放压力时同时释放了一些放射性物质。包括非常小剂量的铯和碘同位素。如果在释放时你正好坐在出口上，那么你可能需要考虑戒烟使得你的期望寿命值回归从前。这些铯和碘同位素会被带入海水，然后就不会再检测得到。 • 第一层护罩出现了一些损坏，意味着一定数量的铯和碘同位素也被释放到了冷却水中，但是不会有铀或是其他什么脏东西（因为氧化铀不溶于水）。在第三层护罩内有用于净化水的装置，这些具有放射性的铯和碘同位素会在那里被去除并且存储为核废料。 • 用于冷却的海水会在一定程度上被活化。但是因为控制棒已经完全插入，所以链式反应是不会发生的。这就意味着“主要的”核反应没有发生，因此也就不会加剧海水的活化。链式反应过程的副产物（铯和碘同位素）在这个阶段也基本上消失殆尽。这进一步减轻了海水的活化。因此最坏情况就是：用于冷却的海水中会具有一定程度的放射性，但是这些海水也同样会经由内部净化装置进行处理。 • 最终会用正常的冷却水取代海水。 • 反应堆核心会需要进行拆除并运到处理厂，就像通常的燃料更换一样。 • 燃料棒和整个核电站需要进行彻底安全检查，以避免潜在的危险。这通常需要 4 到 5 年。 • 全日本的核电站的安全防护会进行升级，以确保他们可以抵抗住九级地震及随之而来的海啸（甚至更糟糕的情况）。 • 我认为更显著的问题是随后的全国供电。日本的 55 座反应堆中的 11 座已经全部关闭并等待进行检查，这直接减少全国 20% 的核电电力，而全国 30% 的电力靠核电供应。我目前还没有去考虑国内其他核电站可能发生的事故。短缺的电力会需要依靠天然气发电站供应，而这些电站通常只是在供电高峰时用于应急。我不是十分清楚日本国内的石油，天然气和煤矿的能源供应链，及港口，炼油厂，存储及运输网络在此次地震中遭受了怎样的损失。这些都会导致电费增加，及用电高峰和重建时的电力短缺。 • 而这一切只是更大的问题的一部分。灾后应急需要解决避难所，饮用水，食物，医疗，运输，通讯设施等一系列问题，当然也包括电力供应。在一个供应链倾斜的时代，所有的这些领域中我们都会遇到挑战。如果你希望持续了解事实，那么就忽略那些肤浅的媒体并关注以下网站：• http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html• http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html• http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/• http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/分享到：人人网开心网腾讯微博新浪微博豆瓣分享腾讯空间发表评论 Click here to cancel reply.您的昵称 (必须) […]
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bill: nukeworker link contains malware that may damage computer. that’s the message I got. if so, Barry should remove the message.
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Greg… Sorry, I haven’t got a notice on my computer for that, but if it is I will let the nukeworker.com webadmins know. Interesting that it is though. That thread is by people who operate reactors in the US.
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> krypton-86
Thanks, Luke, confirming the guy’s “not even wrong” krypton-86 is stable: http://www.wolframalpha.com/entities/isotopes/krypton_86/ve/4s/6l/
Being an “anti” site is no excuse for sloppy.
Looking that up led to this:
http://www.springerlink.com/content/g1764405737222m5/
Journal of Radioanalytical and Nuclear Chemistry
Volume 220, Number 2, 173-181, DOI: 10.1007/BF02034852
Monitoring of fission product release in a boiling water reactor
Only the first page is shown as a picture, it’s paywalled.
Google excerpt is: “klypton-87, krypton-88, krypton-85m, xenon-135 and ….. (2.1 y) is produced by neutron activation of 133Cs, a stable fission product. …”
[Yeah, it does say “klypton” — bad OCR by Google?]
http://www.springerlink.com/index/g1764405737222m5.pdf
For Luke — follow up, the “86″ was clearly a typo, and the guy has it correct elsewhere:
“… Kr-87 has a half-life of 1.27 hours … Kr-87 is an example of a ‘delayed neutron,’ a fission product that emits neutrons after the ‘fission event.’”
So it is in fact a neutron activator, to the extent it’s a delayed neutron emitter — a class of radioactivity I didn’t know existed til today. That’s not a certainty, it’s a low-probability decay path for that isotope, which decays very fast and can go several different ways when the nucleus comes apart, emitting either a beta or a neutron, as I read it.
Still the point is that the noble gas isotopes will get out through almost any containment or filter, though they can be adsorbed, and when they decay some will produce solid elements wherever they happen to be. Dunno how significant a source this is, anyone know?
More: http://www.google.com/search?q=krypton+87+neutron
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And here’s the percentage, it’s quite low; I emailed the contact info about both the “86″ typo (should be 87) and suggesting the percentage info be included.
Nuclear energy: principles, practices, and prospects – Google Books Result
David Bodansky – 2004 – Science – 693 pages
… proceeds to a number of different states of krypton- 87 (87Kr, Z = 36). In 2.3% of the cases, the resulting 87Kr state decays by neutron emission to …
books.google.com/books?isbn=0387207783…
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Satellite photo: http://www.flickr.com/photos/digitalglobe-imagery/5526481182/sizes/o/in/photostream/
More extensive damage to #3, appears to be damage on lower part of building. Steam being vented from at least 5 point. Active boiling of the fuel storage pool?
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NPR radio news just now says Reactor 2 has a stuck valve preventing them from getting water into the core.
ABC news website:
http://www.abc.net.au/news/stories/2011/03/15/3163913.htm
“Operators won’t rule out nuclear meltdown
Updated 8 minutes ago
The nuclear emergency in Japan following Friday’s massive earthquake and tsunami has worsened, with the operators of the damaged Fukushima nuclear plant warning they are fighting to prevent a meltdown.
… government officials are playing down the nuclear concerns, insisting the situation is under control.
…
The fuel rods in the No.2 reactor at the quake-damaged plant are again “fully exposed”, boosting fears of an eventual partial meltdown.
Air pressure inside the reactor at the Fukushima No 1. plant rose suddenly when the air flow gauge was accidentally turned off, operator TEPCO said early Tuesday (local time).
That blocked the flow of cooling water into the reactor, leading to full exposure of the rods about 11pm on Monday, it said.
“We are not optimistic but I think we can inject water once we can reopen the valve and lower air pressure,” a TEPCO official told reporters….”
———
Information on how this started that I had not seen before, from
http://www.greenaction-japan.org/modules/wordpress1/index.php?p=2
“This explanatory piece arrived at 17:55 from Takeshi Sakagami:
Fukushima Daiichi Nuclear Power Station Unit 2 lost its cooling system at 13:26pm.
Unit 2 was initially expected to have a possible core meltdown earlier than Units 1 and 3.
Estimating by the release of information from the Prime Minister of Japan and his Cabinet, as well as news media coverage, the tsunami hit Fukushima Daiichi Nuclear Power Station 50 minutes after the earthquake at 15:40 on the 11th, causing the emergency diesel generators to stop functioning. The Reactor Core Isolation Cooling pump of Unit 2, however, activated its water injection system the moment the reactor automatically shutdown.
A problem occurred at 20:30 when the M/C (Main Switchboard) was submerged underwater. This prevented proper monitoring of pump operations and the reactor’s water levels. The situation had to be managed without proper information from the site.
As a result, at 20:50, Fukushima Prefecture released an evacuation order for those living within 2km of the reactor. The government also released an evacuation order at 21:23 for those living within 3km and a stay-home order for those within 10km of the reactor. The government’s orders were released following prefectural correspondence.
TEPCO and NISA (Nuclear and Industrial Safety Agency) made two predictions for pump malfunctions at 21:00 and 22:00. The prediction for 22:00 had fuel exposure at 22:50, meltdown at 24:50, and a reactor containment “bent” (intentional release of pressure) at 27:20.
At 21:54, water levels were identified as L2(low-low) using temporary power. However, since this temporary power lasted only a short time, there were measures to secure an electric power supply through a power source car. This trial failed, as they could not connect to the source.
The predicted time for meltdown and reactor containment vessel venting
(outer air release) passed without successful power connection.
However, the Reactor Core Isolation Cooling pump was operating. This information was discovered 13min after the predicted time for a reactor containment vessel bent. Water injection continued.
While this was happening, the Unit 1 situation got worse, as its pump was not operating. Problems occurred in Unit 1, followed by Unit 3.
Unit 2’s current state of problems include deterioration of the Reactor Core Isolation Cooling pump function, rising pressure in the reactor, and a lowered water level. NISA stated they would try recovering pump functions by lowering pressure through a reactor containment vessel venting (releasing radioactive inner air to the outside). Sea water was used so as to keep as much water as possible in the reactor containment vessel’s suppression pool.
(translation by a volunteer translator)”
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With good luck the prevailing winds will continue to carry any radioactive products out to sea as they are doing in the photo http://www.flickr.com/photos/digitalglobe-imagery/5526481182/sizes/o/in/photostream/
Seen in retrospective the action should be more prompt when it became clear that the plant suffered multiple failures. Bringing in ships, helicopters and using what was available to power up those pumps, if so by bypassing power directly. Or if coupling external pumps in series to get the water in. As i understrand you don’t need more than 30 bar pressure to get water into the boiler.
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Alright guys. I have looked at aerial photos on unit 3 (http://www.flickr.com/photos/digitalglobe-imagery/5526481182/sizes/o/in/photostream/) any thoughts on the significant steam offgas that looks like it is coming from near the top of the primary containment? I dont think it is the spent fuel pool, as the steam release looks to concentrated in one place. Could it be the connection for primary containment venting to the secondary containment via SGTS?
What are they doing to lower H2 in unit 2? We can guess that main modes of H2 production are zirconium steam and steam steel interactions, right? Given the time, it is possible that radiolysis is signifcant
I am a nuclear ISI engineer. The technical discussion of the safety of these Japanese plants is exactly correct. People need to understand these plants are not bombs. They are not chernobyl, they are fail safe designed. People need to be aware that to environmental groups these plants are “boogie men”.
Ask yourself this question. Nuclear plants have operated safely in the United States for over Fifty years.
How many people have been killed by a Nuclear plant in the United States? More coal miners have been killed in a single mining accident than all of the workers combined over fifty years in a Nuclear plant. And most were not related to radioactivity. How many outside the boundary of a Plant…none
Here is your choice…keep paying outrageous gas prices and be held hostage to foreign oil or advocate for the nuclear power industry and tell the environmentalists to back off because they have no grounds to demonize this industry. You have a greater risk of dying in a plane crash than from a nuclear plant, period.
NPR radio news: US Navy is moving ships farther away from the nuclear plants after detecting low level radiation on several pilots who flew near the area.
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Units 1 & 3 appear to be stable based on reports. Unit 2 is now of concern. Unit 1 & 3 have long term issues to deal with in the spent fuel pools. Those issues can be overcome though barring another act of mother nature.
Continue to watch the reports of radiation levels on site and at the site boundary and airborne release rates. If they really shoot up, things have gone bad. Unit 2 could be the one that causes real problems though as we monitor the situation.
James, I am really beginning to believe that the hard pipe mod to vent the torus straight to the stack wasn’t done, or failed due to isolation valve failure. Hence the hydrogen buildup in the reactor building and ultimate explosion for units 1 & 3.
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Can someone please explain how the seawater is being injected? IANAE (I am not an engineer.) So pretend I’m a teenager …
I understand that a closed vent is preventing the process, but what IS the process? If there is no power, how is the water being injected?
Buckeye, look earlier in this long thread for pictures and sketches; there are quite a few pipes going into various parts of the reactor containment, and diesel pumps are being used. It’s not clear what particular pipes and valves are used or not used or failed, from what I’ve read.
Status:
http://www3.nhk.or.jp/daily/english/14_46.html
(Japan Broadcasting Corporation)
updated at 13:40 UTC, Mar. 14
The utility firm said on Monday afternoon that fuel rods are exposed at the Number Two reactor of its Fukushima Number One plant after the level of coolant water dropped. At around 6:20pm, the power company began pumping in seawater.
Tokyo Electric says it had to halt the process due to fuel loss for the pumping system, possibly leaving the fuel rods in the reactor exposed. The firm says a core meltdown might have occurred.
The Nuclear and Industrial Safety Agency says that pumping seawater into the reactor is working now.
Earlier in the day, the firm told the government that the reactor had lost all cooling capability due to a failure of the emergency power system.
Since then, the company has tried to circulate the coolant by steam instead of electricity. But attempts to lower the temperature inside the reactor chamber have not worked well.
The company is also considering opening a hole in the reactor housing building to release hydrogen generated by the exposed fuel rods.
Accumulated hydrogen has caused blasts at two other reactors at the plant.
Monday, March 14, 2011 20:36 +0900 (JST)
http://www3.nhk.or.jp/daily/english/14_16.html
“TEPCO says the water-drenched equipment and machinery short-circuited after the power plants were submerged in sea water on Friday.
Based on the government’s guidelines, the Fukushima No. 1 plant was designed to withstand tsunami waves of up to 5.7 meters and the No. 2 plant, up to 5.2 meters.
TEPCO says the tsunami waves that hit the plants were higher than 10 meters.
Monday, March 14, 2011 09:53 +0900 (JST)”
Could be a silly question here guys, so hold on…
Saw on the news last night footage from inside a reactor. It’s the news, so obviously they didn’t mention where it was.
This footage showed a ‘pool’ in a builbing, and something that looked like a reactor core at the bottom. Sort of hexagonal honeycomb of rods and things.
So, I’m just trying to marry up this image to how the plant works. The rods get hot and make steam. Is this bath the heat exchanger that provides steam, or the cooling water around the core? Is only the reactor pressurized?
Barry, have you done a ‘Nuclear plants for dummies, that know a little bit already’ post?
EB
Hank, thank you. I did try to review those diagrams before asking. I see the descriptions and locations labeled where the seawater is being pumped in.
My question is about the basic physics of getting the water in. Is the water being pulled down into the containment via gravity, forced in by high pressure, or …? Please excuse my ignorance. (IANAE)
Hank, injection of fire water or sea water is standard protocol for accident mangement. What is really critical is did it get in… and what are the current radiation levels….
As you said there are many ways to inject if pressure is low enough, some more efficient than others… I hope you understand what you are reading on the internet as it must be filtered….
I’m not an engineer, just reading. From the quotes above, they do have some electric power and fuel, not enough fuel sometimes, to run ordinary electric or diesel pumps that they have been using.
I don’t know what “the company has tried to circulate the coolant by steam instead of electricity” means.
All the reporters are saying it’s hard to get reliable information. A lot of this won’t get clear until the crisis is over.
http://www.scribd.com/doc/50582630/Standard-Technical-Specifications-General-Electric-Plants-BWR-4
thanks to em1ss and please, critique and comment and point to better sources as much as you can. You’re among the very few commenters who actually know what they’re talking about here.
(I’m not, I’m just trying to filter what I read not to add opinion nor link to anything that doesn’t cite sources; it’s getting harder to sort out sense from crap as this goes on, tho’-I’m hoping we see some known reliable commenters take on a full time feed, but until the companies and government supply facts, that’s not likely).
http://www.world-nuclear-news.org/RS_Loss_of_coolant_at_Fukushima_Daiichi_2_1403113.html
Loss of coolant at Fukushima Daiichi 2
14 March 2011 FIRST PUBLISHED: 6.14pm
UPDATE 1: 8.04pm Information from Tepco television appearance
“A spokesman for Tokyo Electric Power Company has appeard on national broadcaster NHK to explain the company’s efforts to control unit 2′s reactor core after its isolation cooling system failed following an increase in containment pressure to some 700 kPa.
The company prepared to inject seawater into the reactor system, but this was only started “after the water level reached the top of the fuel.” Guages indicated that water levels continued to drop despite the injection process and after some time injection became impossible due to high pressure.
Opening the relief valve made injection possible again, but after a time pressure relief was again required. Injection has continued since that second venting operation but guages still do not indicate that water levels are rising.
The Japan Atomic Industry Forum reported back statements from the Nuclear and Industrial Safety Agency (NISA) saying that Tepco made a notification at 8.50pm that some fuel rods were presumed broken, based on radiation detected.”
evcricket, that sounds like a open-pool research reactor. While they generate some heat of course, it’s low quantities and there is no attempt to use the heat for power generation.
A power reactor is in an enclosed pressure vessel; the coolant carries the heat to turbines (possibly via heat exchangers).
I ask again, what are the radiation levels currently…. This is protocol response and may be working, but radiation levels determine effectiveness…
Some fuel rod leakage or fuel damage should be expected if as reported the fuel was uncovered for the reported amount of time. Key now for reactor 2 is covering the fuel and maintaining containment through flooding.
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>radiation levels
Reports here at the plant boundary; any others?
http://www.nisa.meti.go.jp/english/index.html
http://search.japantimes.co.jp/cgi-bin/nn20110315x1.html
“Tuesday, March 15, 2011
…No. 2 reactor at the quake-hit Fukushima No. 1 nuclear power plant, as fuel rods became fully exposed again after workers recovered water levels to cover half of them in a bid to prevent overheating.
The plant operator, Tokyo Electric Power Co., said steam vents of the pressure container of the reactor that houses the rods were closed probably due to the battery problem, raising fears that its core will melt at a faster pace.
The firm said it will first lower the pressure of the reactor by releasing radioactive steam and open the vents with new batteries to resume the operation to inject seawater to cool down the reactor.
Earlier, cooling functions of the reactor failed, causing water levels to sharply fall and fully exposing the fuel rods for about 140 minutes. TEPCO said they could not pour water into the reactor soon as it took time for workers to release steam from the reactor to lower its pressure, the government’s nuclear safety agency said.
As TEPCO began pouring coolant water into the reactor, water levels went up at one point to cover more than half of the rods that measure about 4 meters.
Prior to the second full exposure of the rods around 11 p.m. Monday, radiation was detected at 9:37 p.m. at a level twice the maximum seen so far— 3,130 micro sievert per hour — near the main gate of the No. 1 plant, according to TEPCO.”
http://search.japantimes.co.jp/cgi-bin/nn20110315a1.html
Tuesday, March 15, 2011
Reactor fuel rods fully exposed
Coolant failure now reported in No. 2 unit
By KANAKO TAKAHARA
Staff writer
The radioactive fuel rods at the No. 2 reactor of the Fukushima No. 1 power station were fully exposed at one point Monday, Tokyo Electric Power Co. said, raising the possibility that it suffered a partial core meltdown.
The utility operating the Fukushima plant later said the level of coolant water in the reactor’s container was raised 2 meters above the base of the rods — which are about 4 meters long.
However, it was not clear if Tepco was able to pump enough coolant into the containment vessel to cool it off. Nevertheless, Chief Cabinet Secretary Yukio Edano told a news conference Monday evening that the situation stabilized after cooling resumed.
Fears of the worst-case scenario — a total core meltdown — are increasing because the No. 2 reactor’s self-cooling system failed and sea water was being pumped in from outside.
Tepco said the water levels fell because the pump temporarily ran out of fuel and workers failed to notice it quickly enough.
It was not immediately clear how long the reactor’s core lay fully exposed or to what extent it heated up in that time….”
according to the http://www.nisa.meti.go. site’s latest press release:
→29.8 micro Sv/h(14:14 March 14)
MP5 (Monitoring at north-west Site Boundary for Unit 2)
6.1 micro Sv/h(14:02 March 14)
MP6 (Monitoring at the west –southwest Site Boundary for Unit 2)
3.70 micro Sv/h(16:10 March 14)
→4.2 micro Sv/h(12:34 March 14)
MP7 (Monitoring at the west –southwest Site Boundary for Unit 2)
6.1 micro Sv/h (12:16, March 14)
(3) Wind direction/wind speed (as of 14:14, March 14) at MP-4
Wind direction: North North West
Wind Speed: 2.6 m/s
can someone interprete? is the wind blowing back into Japan?
Hank, circulation by steam is a two fold explaination. One is by steam driven pumps, injecting coolant which is ideal…
Second is by steam driven cooling by convection, less than ideal but workable under proper conditions…. This last method relies on wetting the fuel and allowing the steam to rise… removing heat and preventing fuel melt. That’s as simple as I can make it.
I hope the Japs are able to get enough pumping power on site to flood the boilers. Is there any chance that the condensers can be restarted so it wont have to ventilate everything to athmosphere?
For another view of this, see:
http://www.truth-out.org/tokyo-electric-build-us-nuclear-plants-the-no-bs-info-japans-disastrous-nuclear-operators68457
To correct myself, according to the latest press release the pressure is above 65 bar on number 2. http://www.nisa.meti.go.jp/english/index.html
That require some a bit of power, but should be manageable through a series of pumps imo.
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Sadly, we digress into agendas. Forgetting the mental anguish those affected are feeling locally. It may seem that I analyaze the reports positively with regards to the nuclear events. But I hold alot of skepticism for the news reports too and filter them. I don’t trust the media any more than the skeptics here. I am concerned about reactor 2 right now, but withold judgement for now.
Show me the data on significant release rates or radiation level increases on site. Then I will say a major nuclear accident impacting the populous now or long term has occurred. I live in the factual world.
Factually the real horror at the moment is the natural phenomenon that has destroyed an unbeliebable amount of Japan and killed thousands of innocent people. Those that survived are struggling , shelter, food, and fresh water supplies are dwindling…. Never mind the loved ones they may have lost.
Stefan, where’s that “65 bar” from?
You point to the index page; which actual pdf file is that in? I see in the most recent one (en20110315-1):
Unit 2 reactor pressure as .65 MPa and
“PCV pressure” as “Approx. 395″ KPa.
http://www.sensorsone.co.uk/pressure-units-conversion.html
By comparison, “65 bar” is much higher- around the normal operating pressure.
Cripes my spelling is horrible in that due to typing… analyze… unbelievable… need a proof reader it seems and sorry.
Check out the guardian updates. They suggest radiation levels now at 680 microsieverts/hour just north of plant.
don’t know what’s true.
Hank, my bad it’s getting late.. 0.650mpa is 6.5 bar. Does not sound very much at all to me then, a couple of sentrifugal pumps would be able to deliver above that without any problem. But i have only worked with oil boilers, never nuclear so there’s probably more to it than i know.
So 65 bar is normal operating pressure? Then it sounds to me that its some leeway still, as the denser steam also takes away more heat. but again i might be totally off.
Now what?
http://abcnews.go.com/International/japan-earthquake-reactor-fukushima-nuclear-plant-explodes/story?id=13131123#
“Japan Earthquake: Third Reactor at Fukushima Nuclear Plant Explodes
Blast Came After IAEA Said Containment Vessels at Fukushima Nuclear Reactors Seem to Be Working
March 14, 2011
… a new explosion Tuesday morning at a reactor the Fukushima Daiichi nuclear plant, the Japanese nuclear safety agency reported.
The blast, which occurred at Unit 2, is the third at the plant since a powerful earthquake struck Japan on Friday….
The explosion, which occurred at 6:10 a.m., came shortly after the International Atomic Energy Agency had announced that the reactors at the Fukushima Daiichi plant had been shut down. ….”
New blast reported at damaged Japan nuclear plant
http://www.marketwatch.com/story/new-blast-reported-at-damaged-japan-nuclear-plant-2011-03-14
LOS ANGELES (MarketWatch) — Japanese media reported a new explosion heard at the No. 2 reactor of the earthquake-damaged Fukushima Daiichi nuclear power plant early Tuesday morning. Several reports cited government officials as confirming the blast at 6:10 a.m. local time (5:10 p.m. U.S. Eastern time). Officials with the Nuclear and Industrial Safety Agency said the incident may have damaged the reactor’s pressure-suppression system, according to the Kyodo news agency. The plant, operated by Tokyo Electric Power Co. /quotes/comstock/64e!9501 (JP:9501 1,621, 0.00, 0.00%) , has been the focus of widespread concern about a large-scale radiation leak.
Reportedly damaged the “pressure suppression system” shich apparently is the “inerted drywell (primary containment)” surrounding the reactor vessel proper and includes the “pressure suppression torus” at the base of the reactor.
http://www.nucleartourist.com/type/bwr.htm
http://abcnews.go.com/International/japan-earthquake-reactor-fukushima-nuclear-plant-explodes/story?id=13131123&page=2
“… Officials first became concerned about unit 2 at the plant after pressure began rising in the reactor. Officials from the Tokyo Electric Power Co. told NHK News that the explosion at unit 3 might have damaged unit 2′s cooling system.
“They’ve had trouble with getting the pumps working, with site power in general… They’ve shipped in extra diesel generators and they may have to do some extra retrofit plumbing,” Morse said.
… unit 3, which exploded early Monday morning in Japan, reportedly has a leak in its bottom.
The NYT is reporting radiation readings of 3130 microsievarts, which would be 313 REM, a very significant dose.
http://www.nytimes.com/2011/03/15/world/asia/15nuclear.html?hp
Order of magnitude error:
3130 microsievarts is .313 REM an hour
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TEPCO 8270 microsievarts
Thanks for catching that — it’s an order of magnitude error error, actually.
I’ve made some too. Let’s show our work or link to online calculators. We need sanity checks.
Sounds like it’s getting much worse at the site, if the “hole in the bottom” means the torus is leaking.
http://www.nytimes.com/2011/03/14/world/asia/japan-fukushima-nuclear-reactor.html?pagewanted=2&src=un&feedurl=http://json8.nytimes.com/pages/world/asia/index.jsonp
“normally you would just re-establish electricity supply, from the on-site diesel generator or a portable one.” Portable generators have been brought into Fukushima, he said.
Fukushima was designed by General Electric, as Oyster Creek was around the same time, and the two plants are similar. The problem, he said, was that the hookup is done through electric switching equipment that is in a basement room flooded by the tsunami, he said. “Even though you have generators on site, you have to get the water out of the basement,” he said.
Another nuclear engineer with long experience in reactors of this type, who now works for a government agency, was emphatic. “To completely stop venting, they’re going to have to put some sort of equipment back in service,” he said. He asked not to be named because his agency had not authorized him to speak.
The central problem arises from a series of failures…
Inside the plant, according to industry executives and American experts who received briefings over the weekend, there was deep concern that spent nuclear fuel that was kept in a “cooling pond” inside one of the plants had been exposed and begun letting off potentially deadly gamma radiation.
Then water levels inside the reactor cores began to fall. While estimates vary, several officials and industry experts said Sunday that the top four to nine feet of the nuclear fuel in the core and control rods appear to have been exposed to the air — a condition that that can quickly lead to melting, and ultimately to full meltdown.
At 8 p.m., just as Americans were waking up to news of the earthquake, the government declared an emergency, contradicting its earlier reassurances that there were no major problems. But the chief cabinet secretary, Yukio Edano, stressed that there had been no radiation leak.
But one was coming: Workers inside the reactors saw that levels of coolant water were dropping. They did not know how severely. “The gauges that measure the water level don’t appear to be giving accurate readings,” one American official said.
What the workers knew by Saturday morning was that cooling systems at a nearby power plant, Fukushima Daini, were also starting to fail, for many of the same reasons. And the pressure in the No. 1 reactor at Fukushima Daiichi was rising so fast that engineers knew they would have to relieve it by letting steam escape.
Shortly before 4 p.m., camera crews near the Daiichi plant captured what appears to have been an explosion at the No. 1 reactor — apparently caused by a buildup of hydrogen. It was dramatic television but not especially dangerous — except to the workers injured by the force of the blast.
The explosion was in the outer container, leaving the main reactor vessel unharmed, according to Tokyo Electric’s reports to the International Atomic Energy Agency. (The walls of the outer building blew apart, as they are designed to do, rather than allow a buildup of pressure that could damage the reactor vessel.)
But the dramatic blast was also a warning sign of what could happen inside the reactor vessel if the core was not cooled. The International Atomic Energy Agency said that “as a countermeasure to limit damage to the reactor core,” Tokyo Electric proposed injecting seawater mixed with boron — which can choke off a nuclear reaction — and it began to do that at 10:20 p.m. Saturday.
It was a desperation move: The corrosive seawater will essentially disable the 40-year-old plant; the decision to flood the core amounted to a decision to abandon the facility. But even that operation has not been easy.
To pump in the water, the Japanese have apparently tried used firefighting equipment — hardly the usual procedure. But forcing the seawater inside the containment vessel has been difficult because the pressure in the vessel has become so great.
One American official likened the process to “trying to pour water into an inflated balloon,” and said that on Sunday it was “not clear how much water they are getting in, or whether they are covering the cores.”
The problem was compounded because gauges in the reactor seemed to have been damaged in the earthquake or tsunami, making it impossible to know just how much water is in the core.
And workers at the pumping operation are presumed to be exposed to radiation; several workers, according to Japanese reports, have been treated for radiation poisoning. It is not clear how severe their exposure was….”
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Can’t vouch for this but it’s interesting and seems credible thinking, doesn’t have any news in it:
http://hotbabysitter.livejournal.com/32121.html
“… my father works at a nuclear power plant. It’s in southern Georgia …. and is technically a project manager for the plant, not actually a nuclear engineer. Now, obviously, the power plant explosion in Japan is high on the topics of conversation around his workplace. Since he knows that I think his work is really cool and I like hearing about things, he forwarded me and all of his colleagues an email with two highly informative updates on what exactly happened at Fukushima-Daiichi. I’m sure some of y’all already know what’s going on, since y’all are more proactive in looking up what’s going on in the world than me, but if you’re interested in a long, informative update from people in the business, I’m copying it in here ….”
—
[excerpts from that (it was prematurely hopeful, written before the 3rd explosion and report of a leak below unit 2, however)-hr]
“There still is no heat rejection from the pressure suppression pools at any of the reactors so temperatures and pressures are rising and venting is needed. The tsunami destroyed the service water cooling systems. TEPCO is working hard to set up temporary RHR heat exchangers to cool the pools before they get too hot or the seawater levels in the basement areas rise to unacceptable levels.
At Units 1 and 3, I have confirmed that borated seawater is being injected into the depressurized cores with high pressure fire engine pumps. Both Unit 1 and Unit 3 primary coolant systems are now depressurized at 35-50 psig. Core cooling is with the relatively cold injected borated seawater, but the flooded wet and dry wells are filling and this mode cannot be sustained indefinitely without overflows. So within the next day, TEPCO will need to get some decay heat removal temporary heat exchangers operating to cool the wet well, Then they can go into a stable recirculation mode. Once closed recirculation can be achieved the addition of new flooding seawater can be minimized. But water injection/recirculation will likely continue somewhat like this for weeks.
It is actually very similar to how we cooled down the damaged/melted Three Mile Island Unit 2 core using the TMI main coolant pumps and steam generators. Of course Fukushima is a BWR and different, but the principle is the same. At TMI this mode continued for several months while core heat decayed. So much of this is like reliving Three Mile Island all over again.
From various sources I have gathered more information on what actually happened. As often happens, early information can be incorrect, but I think these are correct.
It seems that all the reactors withstood the earthquake ground motion OK. We do not have a comparison of actual versus design basis accelerations, but even though the motion was probably over the design basis, most safety systems seemed to be functional until the tsunami hit. The tsunami was the big problem.
It seems that Fukushima design basis tsunami was 6.5 meters, but the actual tsunami was in the 7-8 meter range. These waves washed the diesel fuel system away, submerged the switchyard and destroyed most of the switchgear. This massive damage to the electrical system prevented rapid hookup of auxiliary diesel generators that were relatively quickly brought on site. So only the turbine driven battery controlled RCIC was available to inject water into the reactor vessel until AC power was restored to the HPCI.
There is no information about the Unit 1 spent fuel pool situation. By now I am sure that TEPCO has the ability to pump water into the pool to maintain water levels. A small fire hose is all that is needed. There is no information available on debris from the explosion or anything else in the pool that is now completely exposed to the environment. Unless heavy debris fell into the pool and damaged spent fuel, this is not a big issue as long as they can keep pool water levels stable, which they should. Given the radiological releases from the primary containment pressure venting, the spent fuel pool releases are negligible.
Neither is there any information on the spent fuel dry storage cask modules that are at the Fukushima site. The Fukushima Independent Spent Fuel Storage Facility (ISFSF) is in the back of the plant site away from the ocean, so it is hard to tell if it was flooded or not. I suspect that wave water got there, but if it did it was a comparatively nothing event since these are passive cans. I believe there is ~100MTU of spent fuel in their ISFSI. But just being there is an issue in itself. Technically it is better there than in the Unit 1 pool without a roof….”
We are now almost four days on from the time the earthquake hit (that would be 4.46pm AEST this afternoon, I believe). The reactors were scrammed at the time of the quake, and the daughter product heat output will have been dropping exponentially since then.
Does anyone know how long external cooling needs to be maintained? I thought I heard something of the order of a week. If so, we should by this time be a fair way along the decay curve for heat output.
This is a probably credible source, just judging by the authors’ bios at the site. It is not a reassuring piece, it has more numbers and details on the spent fuel pool and the dry cask storage than I’ve seen elsewhere — although still far more questions than answers.
Barry, if you have a chance, I recommend a look at this and wonder if you can cite or debunk any of it.
http://dcbureau.org/201103141303/Natural-Resources-News-Service/fission-criticality-in-cooling-ponds-threaten-explosion-at-fukushima.html
Midnight GMT … just watched a live press conference hosted by Tokyo Electric on NHK news.
They said that the explosion at Daiichi No 2 (6:14 am Yokyo time) appeared to eminate from “low in the structure”, that they thought the supression pool casing had been breached (accounting for failure to be able to maintain water level ?), that the fuel rods were currently dry, and that measured levels at the plant gates were currently 8217 micro Sv/hr !
All personell non-essential to the recovery operation had been evacuated.
can someone on this site please explain the current situation and what it means? there was an explosion in the 2nd unit’s pressure chamber? where the suppression pool is. the pressure significantly dropped and they measured 8217 uSv.
does this mean that the 2nd containment has failed?
below is a link to Japan’s nhk broadcast in english.
http://live.nicovideo.jp/watch/lv43296023
Back in the late 60′s early 70′s, the USS Barb SSN-596, a nuclear-powered fast attack submarine, was tied up to the pier in Pearl Harbor for about 11 months while it was outfitted with a new crew. Why? Because the whole crew was busted for dope, Captain on down – nuclear-powered and probably nuclear-armed too. During Nam a lot of nuclear-powered vessels were operated by sailors higher on drugs in the engine room/reactor plant than students on campus at UC Berkely. We only came close to uncovering our Rx core once as a result of emergency and casualty drills gone wrong. Send some old nuke dope-head BTs, MMs, ETs, ICs, and EMs, over to Fukushima. They’d get that place under control – no problem.
> NHK broadcast in English
6:14 AM blast heard near suppression pool of No. 2 reactor and pressure began to fall…. from 3 atmospheres to 1 atmosphere.
Operators not directly engaged in the effort to cool the [No.2] reactor … are being evacuated to safer locations after “blast in the area of the suppression pool — the equipment that coordinates activities ….”
A senior correspondent is interviewed:
“this problem may spread and may become worse. The release of contaminated water to the outside is a very serious situation …. this could be a worst scenario … we do need very accurate information …
The cooling system for the spent fuel pool may have failed on one of the reactors that lost its roof; and mentions as breaking news — Tokyo Electric reports new smoke rising from the No. 3 reactor at around 7am Tuesday.
And temperatures are dropping toward freezing with rain over the next few days, all across Japan.
captaindallas2 said:
“When teenage dopers can operate it, its design is pretty forgiving! Thanks for the real story! Old Guy designs rule!”
Actually most of the guys in engineering that were nukes already had several years of college under their belts. Some even had four-year degrees. There were only a few of us young kids out of high school, and we were at least 20 by the time we came aboard. There are plenty of other stories I could tell all day long. We lifted a primary water relief right next to the pier adjacent the putt-putt golf course in Subic Bay. Hundreds of gallons of raw coolant warmed up the water there a little bit, in more ways than one. How do I know that? I was on the shutoff relief watch with headphones, and had to shut it to stop the discharge. That never hit the press either. But the one that shook up the ELTs on board the most was after they found out that backleakage from the primary to the charging pump head tank had been going on for a long time before someone noticed that the level in the tank was increasing without having any additional water added to it. The ELTs used to make their tea from that 200 degree water. Good thing we never had any clad melts in our cores. They probably only had to worry about Co60 in their tea. Ha! If it wasn’t 451 counts above background on the RM3 frisker, it technically wasn’t contaminated. When our clothes were at 450, we just threw them in the dirty clothes bin and took a shower. Only had 1.8 REM lifetime dose by the time I was discharged. 42 years later, still living from the radiation – if you call this living. Ha!
No. 4 reactor, which had been out of service but still had spent fuel, is on fire. Objects from the hydrogen explosion of the other reactors fell into the No. 4 reactor; hydrogen is being generated so we assume the radioactive substances are being released.
http://live.nicovideo.jp/watch/lv43296023
6:40:20 timestamp
More from NHK World TV, this is a government minister speaking.
“1, 2 and 3 reactors water injection operation is continuing and so far for all 3 reactors water injection is continuing smoothly…. next problem will how to maintain this cooling … and how to deal with … fire in No. 4 reactor. As of 10:22 am according to the monitoring … (millisievert rather than microsievert, now we are talking about levels that can impact the human health. … these are readings taken near the area where we believe the release of radioactive substances is happening …. from 6am the 800 staff that remained in the power plant, all but 50 who are directly involved in injecting water have been evacuated … the situation that I am reporting is of very high concern to all of you and I regret that we are reporting this but in preparing for this scenario we have asked you to evacuate from a 20km radius from the plant …. from the 20-30km radius are we are asking you to remain indoors, do not go outside but remain indoors, and … please keep the windows shut. Do not use ventilation equipment ….”
This is a government minister speaking.
Correcion, captdallas2: It’s wasn’t raw coolant, as the volume of water discharged was out of the pressurizer, so relatively stagnant. Plus, it was most likely less than 100 gallons, plus or minus, 50. But the ELTs still glow in the dark today. Just kidding. I think the high pH water gave them the runs. Ha!
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
The above is my typing while listening to the NHK TV live stream, as close as I can come.
Questions now being asked:
Q: … pressure vessels being damaged? …
A: … No. 1, 2, 3 … injecting water … please contact Tokyo Electric … pressure has also been stabilized … utmost effort to maintain this level ..
Q: … fire in the No. 4 reactor … more serious?
A: … No. 4 incident occurred earlier than the No. 2, that’s why I talked about No. 4 first.
Q: … No. 2 pressure container?
A: …I have a report … high probability the compression vessel was damaged.
Q: … fire … is an ordinary fire?
A: … just like other reactors the No. 4 reactor is emitting heat … the fire that we are seeing at No. 4 reactor is not the type of fire that ignite some hazardous materials but the operators are now working to extinguish the fire in the No. 4 reactor as well….
Q: … evacuation radius?
A: … final decision was made by the Prime Minister … now asking the people living in 30 km radius from the plant to stay indoors… considering the current level of radiation reading …
Q: radiation reading quite high?
A: [could be the No. 4 reactor fire/
Q: if the No. 4 fire continues what could happen?
A: … we are making every effort possible to extinguish the fire…. the spent fuel is not going to catch fire in a general sense, the fire is being caused in the building really but … we don’t want the temperature to go up, if heat is created it may also cause radioactive material to be released.
Q: any possibility … release due to this fire? …
A: … a certain … may be released, but I would like the Tokyo Electric Power Company to give the actual figures. The current high readings are we believe from the Reactor No. 4 fire ….
That was an interview with the Chief Cabinet Secretary
Radiation levels at 10:20am
30 millisieverts at No. 1
Around No. 3 400 millisieverts
Around No. 4 100 millisieverts
“much higher than microsieverts”
[…] • http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ • http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/ […]
If I heard right the Japanese prime minister corrected himself from 400 micro Sv/hr to 400 milli Sv/hr measured between no 3 & 4 reactors !
Thats 40 REM …. think you’d rather want to limit your exposure to that !
It seems that the spent fuel pools at Reactor #4 are on fire?
Hi there, long time reader of the site but this is my first post.
I need some reassurance here, from what i’ve read no matter how bad things get we WON’T actually see a meltdown of Chernobyl status, is that correct?
Reason i need to know is i have vouched my new dirtbike against this happening to a bloke that is snowboarding in Japan at the moment as per here:
http://www.dirtbikeworld.net/forum/showthread.php?t=79039
I have faith in Barry’s take on the situation, i’m just hoping i haven’t put too much faith in him.
> It seems
Premature — rumor is not helpful.
Wait and see. That’s all we can do.
> Rodeo
No, Chernobyl design uses carbon blocks — like high quality coal/charcoal — instead of water, between the fuel elements; all of that carbon burned, along with the fuel, in that situation.
It’s still plenty bad, but not bad in that way.
[…] Posts Fukushima Nuclear Accident – a simple and accurate explanationDiscussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquakeJapan Nuclear Situation – 14 March updatesFurther technical information on Fukushima reactorsTEPCO […]
http://live.nicovideo.jp/watch/lv43296023
TEPCO interview at 7:37, guy in a white coat with big diagrams and a pointer. Translator speaking, my typing as I listen:
“965.5 microsieverts”
“the level continued to go up”
“as of 8:31 near the front gate, 8,231 microsievert”
“9:38 am in the building of the No. 4 reactor a fire broke out but shortly before that after the explosion at the No. 1 reactor they found some damage at the building of No. 4 and … maximum level at 8:35 am … leakage could be gas or liquid …
…
7:05am this morning … unit No. 3 the pool which had spent fuel because of the hydrogen explosion … this pool … to store the nuclear spent fuels … usually they circulate the water … there is no cooling function right now … there is some steam above the building … No. 3 … they do not know the reason or the correlation between the steam and the explosion ….
It goes on and on.
So how quickly does this stuff in the air fizzle out?
Anything above 1SV dramatically increases chance of death.
http://en.wikipedia.org/wiki/Radiation_poisoning#Exposure_levels
[…] Japanese nuclear reacTors and the 11 March 2011 earthquake […]
@Rodeo – You won’t see precisely the same type of problems as at Chernobyl, but it is beginning to approach the point where the impact will be as bad.
The fire in the reactor 4 looks like it might causing radiation leakage somehow (judging by the jump in radiation measurements). I don’t think anyone can say how bad that will get (if spent fuel is exposed somehow then it’ll be pretty bad).
The containment pool damage is pretty serious but probably won’t cause as much radiation to escape as broadly as at Chernobyl in itself.
The worst case scenario is that the containment pool integrity is lost, spent fuel is exposed in reactor 4 and and aftershock causes another tsunami. That could be a lot worse than Chernobyl. That’s kind of a sci-fi scenario, but at this point everything else has gone wrong – why not that too?
If you have a choice, I’d get out of that bet. You might win, but at this point it is more likely than not that you will be winning on a technicality.
Hi, I’m glad you like my nhk link. the fire in the reactor #4 has been put out. the 400mSv, I am wondering does this mean the area around the plant will become uninhabitable? what are the effects on crops and lifestock? this area is heavily agricultural in Japan
[…] • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Seems like 4 – 5 unprotected hours “on site” would give you LD50 exposure (as likely to die as medium term survive) …
Also seems like the fire in No4 is from the open spent fuel pool, rods that can go critical if they’ve been rolled together by the quake. Not a good local scenario given that the wind has now turned in a SW Tokyo direction !
Chernobyl as has been explained a hundered times before was a live core explosion and ensuing fire in the graphite moderator, which unlike dissipating and condensing steam in water moderation was carried high into the atmosphere to circle the globe … not going to happen here.
Thing is that these GE BWRs don’t have core catchers as the control rod servos are in a room at the bottom underneath the reactor vessel, so you’re putting trust in primary concrete containment which in the case of No2 seems already to have cracked …
Radation levels – map or Japan. 10am 15th of March
http://twitpic.com/49l8y5/full
Trying to stay on top of everything the best I can with no prior background at all, but I have a question (and it might be a dumb one, apologies):
A lot of us here in Tokyoare wondering about this guys home counter readings:
http://park18.wakwak.com/~weather/geiger_index.html
Is there enough information here to constitute any conclusions?
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
> home counter readings
Can you read Japanese and tell what he’s counting? Gamma, beta, alpha?
I’d say he’s showing he’s detecting a change, but a very minor one compared to the natural background.
Look at the counts per minute he’s showing (from a baseline of maybe 15 or so, eyeballing the picture, with an increase then a spike to around 80, then decreasing).
Then compare:
Click on the page link for Black Cat, the company that makes the device; look at the counts per minute the same device used to test fresh lint from a clothes dryer immediately after drying your clothes:
http://www.blackcatsystems.com/pics/GM/Lint.gif
That chart starts at around 4000 and drops off over a 3-hour period to around 33 counts/minute.
You can find charts made using the same device during a jet aircraft flight, and see how much radiation you get by being above most of the thickest part of the atmosphere.
It’s useful information; don’t panic; make comparisons.
[…] • http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
just pray for them that their nuclear station will be fine.
Thanks for the excellent information being posted.
I should state I am a firm believer in science and the ingenuity of man, and that given our deep understanding of nuclear physics and materials that safe nuclear generation is totally feasible in principle.
The reason I am posting now is to follow up on my previous post where I raised concerns about the lack of, yet essential need for, a healthy respect for the dangers of nuclear power that was absent in these discussions. The accidents that have, and continue to impact, fukushima are I claim evidence of such a lack of a healthy fear (dare I say complacency) in the designers and operators of that plant.
It might be interesting for readers to know that strowger telephone
exchanges circa 1950s to 1980s also had a generator and battery backup for mains failure but that those battery lifetimes were well in excess of those for this nuclear power plant!
The diesel generators in this plant were exposed to tsunami water damage which amazes me in a plant located by the sea. I think we have been extremely lucky that the batteries were not also immediately damaged, especially when in many such back-up systems the generator and batteries are often in close proximity. Whether immediate shutdown could have occurred without batteries is not clear to me but one hopes gravity was properly employed.
There was then no external way to mechanically or electrically spin the fans to vent hydrogen from the containment building alllowing inevitable build up after venting which itself might be considered to be likely, or otherwise very possible, on a mains electrical failure.
We then have a vented hydrogen explosion in one building which was in range of the critical systems for another reactor, leading to a deck of cards scenario.
I won’t go on but this just all smacks of incredible design complacency, especially for a reactor by the sea in a major earthquake zone (given existance proofs from Indian ocean tsunami and chillian quake). And the Japanese where cited as being the safety experts earlier in this thread, and by the media commentators. Very concerning.
Now I have read and heard many times during this incident how this all has nothing to do with Chernobyl, nothing to do with the new designs on the drawing boards or those being installed. Well I beg to differ. The common elements are people, companies, profit, and politics. The science is rarely the issue in this area in my book…its just what else goes into the design, engineering and construction.
In the good old days, nuclear scientists worked for governments and the experts represented the people. Universities were funded by the people so controlled the debate and research agenda, and open and informed dissent could flow leading to open solid design evolution, operations and review.
The world is now very different. We have major companies sponsoring and directing the research agenda and pressuring governments towards another nuclear future. We have commercial based designs and operations for whom profit is the sole aim. We have company group dynamics, the pressures to succeed, meet expectations and unlock bonuses, as well as to save face. In parallel, we have a very real and hard cost/benefit competition with fossil fuels and other alternative energies.
I do not believe for a second that there is enough focus on safety in the industry, nor enough of a margin over other competing fuels to consider, justify and afford the investment in all necessary safety measures. The industry, just like all other industries, will do the minimum required by regulators to meet hurdles, and get through the remaining forums of open debate, to get the contract signed and the bottom line enhanced.
In my mind, Nuclear power is not safe now, nor in the near future, because of that current academic and commercial environment.
A few here commented how earlier this week how brilliantly the fukushima plants were doing given that they were never designed to withstand that size of an earthquake or tsunami. That to me says it all. We don’t care about flawed design requirements..we care about our health and that of our kids and our environment, and need the nuclear industry to behave, to engender trust and build for our design requirements, for the worst case, and not those requirements that enable big profits in the face of competition from fossil fuel and other alternatives.
I hope things get better because we all need a better option that coal!
///Now I have read and heard many times during this incident how this all has nothing to do with Chernobyl, nothing to do with the new designs on the drawing boards or those being installed. Well I beg to differ. The common elements are people, companies, profit, and politics. The science is rarely the issue in this area in my book…its just what else goes into the design, engineering and construction.////
You mean like ‘Neutron Leak’ in today’s fuel rods? The fuel rods get too hot, they expand. Neutrons leak out, shutting down the reaction and cooling down the core — even if Homer Simpson is asleep.
Why do nuclear plants depend on external power after a SCRAM? Couldn’t the energy generated by decay heat power a small generator to maintain coolant flow?
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
@ Righto….congratulations on being one of the first to jump in AFTER it appears that the shit has hit the fan, to denounce our most viable future energy source.
What is the option that YOU would promote to secure our base load power requirements?
I just wanted to throw in a bit of support for Barry who is a fellow Adeladian.
He has done an awful lot of work to provide this site, the threads and the good background and theoretical information for us all. He is an academic and is entitled to his opinions and his findings, and from what I have seen he is open and thorough in his academic processes. He clearly has a personal agenda from his very public pro-nuclear position, and these public academic positions are always capable of coming back and biting you in the bum.
At the end of the day, the guy works passionately to try to find ways to mitigate the growing effects of climate change – a noble cause for sure.
In all matters, academic theorising and positioning has to be married appropriately with solid scientific and engineering experience, a healthy respect for the unexpected in volatile situations, and practical savy of the dark worlds of industry and commerce.
But I personally thank him and his nuclear colleagues for the excellent work that has been done here to make us informed on the design of this reactor and its theoretical behaviours and limits.
I think we all have learnt much from this, will continue to learn and will hopefully come out of this with a better and more balanced views, and a healthier respect for nuclear risks, our reasonable fears and associated design requirements.
[…] of power plants (Maggie Koerth-Baker 12/3/11) The Fake Japanese Nuke Scare (Seán Linnaner 12/3/11) Japanese nuclear reactors and the 11 March 2011 earthquake (Barry Brook 12/3/11) Nuclear plant issues in Japan are the least of their worries (Rod Adams […]
So to all who are already declaring nuclear dead, what *is* the pollution level? What *is* the status of the Containment Dome?
Vampires is derogatory? How quaint. What do you call the press reporting how to mitigate LD 50/30 precautions for the population around the affected power plant. I thought Vampire was a little understated compared to what I was thinking. My my my, people were less precious when I haunted Adelaide.
> addinall
Bogus claim about the BBC page; read the actual page; they’re giving standard advice, the same advice being given at the time on Japanese television for people inside the 30km radius, and consistent with the reported readings.
If you thought they were trying to scare you, you don’t understand the problem and if you advise people to ignore the directions you’re part of the problem. Please think harder and cite sources-then quote correctly rather than parodying them.
“http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/
UPDATE AS OF 10:20 A.M. EDT, TUESDAY, MARCH 15:
At 8 p.m. EDT March 15, a dose rate of 1,190 millirem per hour was observed. Six hours later, the dose rate was 60 millirem per hour, IAEA said.
About 150 residents near the Fukushima Daiichi site have been checked for radiation and 23 have been decontaminated.”
At the peak, it was a great concern; we’re fortunate that the peak was a short term high rate.
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
@Freon
I believe that is what drove the coolant for eight hours after the tsunami – auxiliary pumps driven by the steam pressure from that decay heat process. But they need control power (from batteries in this case) and that’s what failed at that point. (Corrections welcome.)
I’d also like to laud the effort by the creator and moderator (Barry?) of this site, and those who’ve contributed to my understanding here. I truly appreciate the deletion of any drift into acrimony, name calling. Bad manners suck.
Having worked in tech pubs and video production for an oil and gas turbomachinery mfg, I know how difficult it is to get good info, let alone communicate both the big pic and boundary conditions, why great machinery and the best engineering is still valid, in use and marketable, in spite of individual installations demonstrating ‘rapid unscheduled dissassembly’ potential.
So it turns out that MOX (a Plutonium fuel blend) was in use in a now-scrap legacy reactor #2 at Fuku Daiichi. And the H2 blast-demolished penthouse structures probably covered some large spent-fuel cooling pools that can’t be taken for granted after ‘the big one’. That’s just how it is. My prayers go to the engineering workers, regular folks whose families, if they survived, are in a major disaster zone.
Now it’s time for this nuclear skeptic to go surf under the twin domes at San Onofre (SONGS). Really. I’ll be looking at the seawall there, wondering where the diesels and gravity-feed emergency cooling water is kept. I’ll be back here later, listening to this amazing group effort to know something about unfolding events in Japan, and trying to keep my opinions to myself.
Thanks again, for this site.
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
First, thanks for the details on the reactor situation. As I learn more about it I got few questions and was hoping that some experts can share their thoughts on it. Thanks.
As of now, the primary containment system in Unit 2 seems damaged.
1) With fuel rods partially uncovered and heat/steam formation continuing, can the build-up pressure cause the primary containment violently destroy with the release of uranium fuel into the air or would the ventilation system prevent it 100%.
2) In full meltdown scenario, the fuel pellets end up on the concrete core-catcher. Zircaloy cladding disintegrates around 1200 C while uranium oxide melts at 2800 C. If all water evaporates, would those temperatures melt thru the concrete (whose components start melting below 1000 C? That would lead to environment contamination.
3) What magnitude aftershocks (>7 on Richter?) cause the damaged primary containment disintegrate and result in fuel getting into the ground? I assume it would not go into the atmosphere as the reactor is underground.
4) The spent fuel problems in Unit 4: is it kept in a similar cement primary containment system under water? If it becomes exposed and heats up, its low radiation level would not allow a breach and environment contamination, true?
Thanks again
Is there any source on the web which monitors the actual radiation level around Fukushima in different distances?
Best wishes to this excellent web site!
Re the fire, apparently re-igniting today, in the #4 spent rod repository:
What component of the mix is likely to conflagrate first?
Any information on what might be going on there, besides a failure to keep a minimum cooling flow of H2O going?
[…] http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
[…] • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
the cooling pools that the spent fuel rods are stored in are open at the top. It is very likely (though I do not know for certain) that these cooling pools lost a great portion of their cooling water during the initial earthquake. This would be similar to videos from Japan showing swimming pools “sloshing about”…..
[…] internet and media right now about the Fukushima nuclear reactor situation. In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, […]
02:00 GMT – Japanese secretary of state holds a press conference to confirm that the “white smoke” billowing from the Daiichi plant for the past two hours is indeed from No 3 reactor and most likely is steam escaping through another primary containment breach.
We know that No 2 which looks “relatively intact” has a breached suppression well, but that never emitted smoke / steam like No 3 is now doing. Also its not clear if any water is currently being pumped into No 3 as it seems most workers have evacuated.
Also the minister said that although the fire in No 4 is seemingly out, despite the best part of a day they have not yet pumped any control coolant into the spent fuel pool which they believe to be at critically low level … that they have not been able to go near it because of the radiation levels !
Maybe I misheard but I thought a figure of 1000 milli Sev / hr was mentioned … but I’m now hearing that evacuation was caused by 6.8 mSv.
I’m a novice as regards the physics involved but could a meltdown of fuel create enough critical mass to restart sustained fission, or do you need moderators to be present to convert the fast neutrons to thermal neutrons ? Is fuel with a mix of heavier uranium isotopes or reprocessed MOX more susceptible to criticality without the requirement for neutron slowing ?
Also I’ve seen pictures on Japanese TV of how closely the spent fuel assemblies are stacked in the pool, almost reactor density, so again if the boric acid control depletes what happens ?
As a deep water oil production controls engineer our big enemy is water ingress at unimaginable pressures, and so its ironic that these problems all seem to stem from the tsunami causing just a few bar temporary but destructive flooding of the controls electronics and switching relays … surely IP66 or 67 should have been mandatory in that region ?
Not a failure of the structure or the hydraulics but as simple as electrics and water dont mix !
News rpt says they pulled 50 workers due to high levels of radiation. NYT stated that these were technicians at the plant. Does anyone know if firefighters are still trying to put out the blaze and are not counted as the 50 pulled from the site? Without anything being done, wouldn’t radiation levels keep increasing over time? Have they given’t up the fight by pulling remaining workers out?
Seems like the issue with the cooling pools in reactor 4 have more to do with the backup generators going down than it does with an earthquake.
I mean if the earthquake had caused that much water loss, then the radiation levels measured would gone sky high the day of not yesterday.
Cy the techs are pulled when levels get to high but once they go down they’ll go back in.
They’ve withdrawn … we’ll see what’s happening tomorrow.
Systems engineering is the issue … but why don’t you think the generators going down had nothing to do with the earthquake or tsunamis?
This ain’t a coincidence, sheesh!
The reality is that the earthquake and tsunami combined to fubar everything. To dismiss the importance of the earthquake and *inevitable tsunami (a Japanese word)” is idiocy.
Nikkei:
“Cy the techs are pulled when levels get to high but once they go down they’ll go back in.”
Oh, yeah, it’s so normal like … this is the first time *all* workers have been withdrawn.
And I very much doubt that Nikkei is as advertised …
From the press conference today
At 10:00 am the levels measured at the front gate rose to 800 microsv
It peaked at 10:45 when it was at 6000 microsv
The last reading at 11:00 am japan time was
3000 micosv
Another rpt: Japanese officials talking to US military about possible help. Anyone know what can be expected from the US military that the Japanese have not been doing?
dhozga please stop acting like a child, it’s really not the time for it. This is a pretty serious matter and your immaturity really does no one good.
By the way, I was responding to a previous poster. If the earthquake had really caused the water loss in the pool at reactor 4 the radiation levels would have gone sky high that day.
The issue here is the same as the issues with the other reactors. It’s the lack of power to keep the pool cool. If it’s not not kept cool, the water temperature rises and water level goes down due to evaporation.
This was because of a 10meter tall Tsunami flooding the diesel generators cutting the power. That’s quite a bit different from saying that there was a loss of water because of the earthquake shaking which was what an earlier poster wrote.
Also the techs being removed when levels become too high has happened today and yesterday as well. Once levels decrease they are let back in.
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Some ideas : I am a bit concerned with the fact that the salt concentration will increase as cooling with sea water continues. Water evaporates but salt will get more and more concentrated. Boron addition will also lead to forming crystals at the high temperatures existing in the reactor. This could further limit the flowrate of the cooling media. Demin water should be brought to the site by tanker (ship) and send to the reactor using the power plant primary loop using the feedwater pumps (flooding the the turbine, condenser).
This could maybee provide a more efficient cooling system.
Cy I don’t think the US military are going to do anything new, let alone something the Japanese haven’t been doing.
I wouldn’t be surprised if they were asking the US military for equipment assistance if anything. Either that or assistance in filling up that spent fuel pond in reactor 3.
Very detailed information from the german “Gesellschaft für Anlagen- und Reaktorsicherheit “:
http://www.grs.de/informationen-zur-lage-den-japanischen-kernkraftwerken-fukushima-onagawa-und-tokai
Unfortunately only in german but tables and charts are mostly self explanatory:
http://www.grs.de/sites/default/files/images/Messungen_Japan_16.03_15%20Uhr_klein.png
http://www.grs.de/sites/default/files/images/Status%20KKW%20Fukushima%20Daiichi%201900%20Uhr%20am%2016-03-2011.pdf
I forgot:
For those who wonder what kind of organisation the GRS is, here the profile in english:
http://www.grs.de/sites/default/files/unternehmen/GRS_Profile_2011-01_en.pdf
Great discussion. I have been following it since the start. Some really great and thought provoking reading that has greatly helped me “lean” how bwr work over the last 5 days.
I’m a young nuclear professional who started working at a pwr station so thats what im familiar with. We have done mods to our station that would have HUGELY helped this situation. For one the Passive Auto-catalytic Re-combiners would have helped these guys quite a bit.
Anyway I have a question, please bear in mind that I am asking this in general and not considering unit specific problems…until mentioned otherwise. Please correct if I am horribly wrong along the way.
So they are cooling the cores using diesel drive fire pumps to inject sea water into the reactor vessels. If the cores are uncovered…that means either steam above the vessel or a break in the reactor vessel below the fuel lines preventing filling of the vessel.
From what I understand there isn’t a whole in of the problem units. So its not that. So it can only be steam in the RPV…well steam and other non condensibles.
So my question is How is that steam leaving the RPV and being condensed or ected from the system so that heat can leave the reactor and therefore the core can be cooled
Do they direct it strait from the rpv to the containment and then into the suppression pool?
Then my next question is…if they are not doing the above..how are they actually cooling the core by “injecting sea water”. All that water has to go somewhere as steam or water. Where is it going to.?
I have another follow up question to this so I’m looking forward to your response. Regards.
Re water loss from the spent-rod cooling pools:
These things are built to keep the rods many meters below the open surface, so while ‘sloshing’ under the 9.0 displacement must have happened and shortened the boil-off interval, it also seems likely that the pools may have been compromized and drained into the lower parts of the reactor buildings, with unknown effects on the electrical and mechanical components there.
Those major gas explosions may well have emptied the pools also. In the video I see a huge mass of liquid-phase water cascading down, after being thrown aloft by a weapons-grade blast effect.
I’m wondering if the spent rods in the blasted buildings may have been thrown out of the pools, assuming the pools survived. It’s clear now that the pictures being shown Mar 12-15 were several days old, and likely selected for angles that didn’t show lower walls that were demolished, beneath the surviving penthouse frames.
I found the english original of the german PDF I just posted:
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300273535P.pdf
From the japan industrial forum website http://www.jaif.or.jp/english/
Re: the SFPs
Anyone have any theories on how the situation in the spent fuel pools at #4 occured in the first place? Some alarms must have gone off once the water level started to fall? It seems to me that they should have had enough time to hook up some auxiliary pumps once the lights started to blink…?
Rice, although #4 was in cold shut-down mode, it’s SFP contained rods more recently in use, and therefore radiologically and thermally hotter than 5&6 SFP’s. If as reported there are 8 sets of fuel rods in SFP#4, that may represent greater storage mass and density, as well as the freshest set.
In addition, 4 was adjacent to the H2 blast wave from #3. It appears that reactors 1-4 are paired on/in larger buildings, and could share ducting and passageways that would internally contain, communicate, even locally focus the supersonic blast shockwave that can be seen dissipating for >100M outside, even in low res.
We’ve been hearing about the double-whammy of 9.0 EQ and a huge tsunami hydro-hammer-flood. But the atmospheric over-pressures from the multiple H2 explosions means it’s more like quadrupple consecutive shocks, each individually above the DBA (design basis accident) parameters.
Those DBA assumptions didn’t allow for simultaneous loss of emergency aux power and grid power, reactor overheat-overpressure followed by explosive H2 shock-waves.
Given the sea-water flooding and loss of containment, large scale radio-contamination of the near shore seems inevitable, a reasonable choice to keep the reactor site workable
I hesitate to link cable news, but this 3/15 in-depth CNBC piece contained more information in one place than I’ve encountered, although events continue to overtake yesterday’s news.
http://www.americablog.com/2011/03/maddow-heres-what-nuclear-meltdown.html
Hat tip to MB for the JAIF site.
This table is a table summarizing the status-of-record of all 6 reactors and SPF’s on one page, in plain english.
Status of nuclear power plants in Fukushima as of 19:00 March 16
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300273535P.pdf
[…] • http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/ […]
Can anyone explain the green “slag” and “fog” shown in this helicopter video footage at around 48-59 seconds, and 2:10-2:35?
http://www.cnn.com/video/#/video/world/2011/03/17/nhk.aerials.reactors.nuke.plant.nhk?hpt=C2
Much appreciated….
Can anyone explain the purpose of dropping water from a helicpter if the primary containment structure and the reactor vessel itself is still intact? I think it would provide no cooling benefit unless the reactor core is exposed…
The workers in japan trying to manage the issues at the nuclear power plant are a testimate to the nuclear industry.
Rather than providing a negative for the nuclear industry, the impacts that the nuclear facility has withstood and the response of the Japanese nuclear workers whould be a sign of how safe nuclear power is.
D714: Water from helo-buckets and fire-hoses is aimed at the #3 spent fuel pool. That pool, and the #4 SFP are near the top of reactor buildings that are so shattered (just look at the pics) that there is some hope water will splash down into exposed pools, which have cooked dry enough to burn and emit smoke laced with iodine and cesium. I believe that #3 reactor, thought to have compromised containment, is part of the MOX (plutonium-uranium) pilot program. So getting that SFP under control so work on reducing Pu reactor leakage there can commence is a priority. The SFP’s in 1-4 are thought to be the greatest source of leaking radiation at this time, with the potential to get much worse in magnitude and variety of particles release. Without external power, SFP’s in 5 & 6 are said to have rising temperatures, falling water levels.
If you go to the JAIF site linked above, and look at the status report tables, you’ll see that reactor containment is thought damaged by the TEPCO operator on #2 & #3.
Ryan, anyone who is sees multiple reactors and SFP’s damaged to a degree that makes work to contain the leaks almost impossibly dangerous, and guarantees permanent quarantine of property beyond the perimeter of the plant, that somehow proves the general safety of nuclear power? That person is not being careful about their own credibility.
Putting MOX fuel in an old reactor, designing them with the uncontained SFP’s so close to the reactor, letting these roof-top SFP’s become densely packed with decades worth of high-level waste, the lack of gravity fed emergency cooling water: These were not comforting signs of a careful industry, even before the earthquake exposed them as dangerous practices.
http://www.2011earthquake.net
Latest Earthquake News
@WW,
That last post was a test.
I previously attempted to post the extact opposite of that argument on this wall and it was taken down by the site moderator.
I wanted to test whether comments were being taken down merely because they were not technical discussion about what was occurring, or because they did not support Mr Brooks agenda on Nuclear Power.
Seems like the later was correct, and confirmed my suspicions about Mr Brooks.
MODERATOR
Comments, which are personal opinions and attack people in a negative fashion are a violation of the Commenting Rules and are deleted.
Ryan,
given the inflammatory and motive attacking nature of your post here, I can only assume Barry removed your post because it was either ‘playing the man and not the ball’ or was actually full of [ad hom deleted] misinformation. When Barry is getting a million hits a week, he doesn’t have time to suffer [ad hom deleted]
////The workers in japan trying to manage the issues at the nuclear power plant are a testimate to the nuclear industry.
Rather than providing a negative for the nuclear industry, the impacts that the nuclear facility has withstood and the response of the Japanese nuclear workers whould be a sign of how safe nuclear power is.////
If you posted the reverse of this you’re actually attacking PEOPLE who are potentially giving their lives to prevent a disaster. You’re also attacking a nuclear technology that is outdated. You obviously haven’t heard that these Japanese reactors are older Gen2 reactors, and we now have exponentially safer Gen3 reactors with “Neutron leak” built into the fuel rods so that if they overheat they expand, leak neutrons, and the reaction shuts down. And this is as a completely last resort because:
* Homer Simpson has fallen asleep at the wheel,
* aliens have invaded and shut down the cooling systems (because Australia wouldn’t be building them anywhere near Tsunami prone disasters)
So, basically, if you were making generalisations about the whole UNIVERSE of nuclear power from these old reactors, you were being foolish. But if you were attacking the workers involved — some of whom might get radiation poisoning to prevent this disaster — then you are a [ad hom deleted]
Eclipse, fair enough assumption given that I wrote that it was “exact opposite” but incorrect.
The post also praised the workers, but stated that theey should not be placed in such a horrible position of having to put their own health at risk to save the health of others, and that this is the intractable issue with nuclear when things go wrong.
It did not play the man, nor contain misinformation – but rather an oppinion baseed upon fact which was reasonable and fair to make. Giving the moderator the benefit of the doubt, I though this may have been because it was not a technical post. But given that my last pro-nuclear post was posted and was non-technical it looks like this site has an agenda of stifling comments which are anti nuclear.
Also my comments were not imflammatory or attacking, but simply a statement that only comments which support Mr Brooks agenda are posted. Interestlingly the two responses I get were immediately “playing the man”, calling me a “fool” and a “heatless bastard”. Interesting indeed.
MODERATOR
The ad homs have now been deleted. Apologies.
“MODERATOR
Comments, which are personal opinions and attack people in a negative fashion are a violation of the Commenting Rules and are deleted”
This was posted on my comment above.
1. The comment that was removed contained no reference or attack on any people as the moderator should well know. But by posting this, and not my actual comment, the moderator has effectively insinuated to others otherwise. I hope such was not intentional.
2. The two last posts called me a fool and a heartless bastard, in accordance with the apparent moderator’s comment policy I await them to be removed.
MODERATOR
Please re-post your original “in contention” post, giving appropriate references to your
personal analysis re the risk to health of the workers the workers on site. You are correct regarding the inappropriate adjectives used toward you and they will be edited. I apologise .Please understand that I am only human and have been wading through thousands of posts for the last 6 days with hardly any sleep.
Get some sleep Barry. You’ve been hard at it — all over the blog, all over the media, all over TV and blogs and interviews. It seems like every time I turn to a different news source another TV interview with you crops up!
Go for a walk and have some fun with the family, watch a funny movie with your wife, you’ve earned it!
Ms. Perps, on 19 March 2011 at 2:10 PM said:
@ Ryan 234
You said :
“The post also praised the workers, but stated that theey should not be placed in such a horrible position of having to put their own health at risk to save the health of others, and that this is the intractable issue with nuclear when things go wrong.”
Perhaps it was your personal opinion that the workers were in fact putting their own health at risk (I assume without relevant authoratative references)that got your post removed.
If I had my husband/son/brother etc working there I would not want to read your doomsday scenario. Remember there are many Japanese residents using this site for real information not conjecture.
SORRY – POSTED THIS BEFORE ON THE WRONG THREAD.
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A friend of mine had an idea I would like to put out there to people who know more about this issue.
The steam that comes off from cooling; I am guessing; carries a fair bit of toxicity.
If ceramic glazes, which have a curing temperature right around the temperature of these damaged reactors, are dropped enmasse on the reactors; could that form a good plug to then cement over?
Useful link comparing relative radiation doses.
http://xkcd.com/radiation/
[…] are strictly reductionist and don’t properly explore the risk envelope (an early comment on BraveNewClimate stated “There is no credible risk of a serious […]
[Comment deleted. Please re-post on the correct thread – Fukushima Open Thread. We do not have the ability to move comments between threads.]
There is a lot of confusion as to what levels of radiation and exposure are not safe. The following link clearly explains how radiation dose rates and exposure limits are determined by epidemiology studies to protect the public and nuclear energy workers in Canada. The risk assessment is based on national data plus inputs from international groups of experts in radiation protection:
http://nuclearsafety.gc.ca/pubs_catalogue/uploads/March-17-2011-INFO-0812-Setting-Radiation-Requirements-on-the-Basis-of-Sound-Science-The-Role-of-Epidemiology_e.pdf . March 2011
Is it possible that the latest release of steam ,that does not appear to have caused a radioactivity spike is one of the pressure relief valves on the cooling water pipework, or the core injection pipework?
The Japan Nuclear Technology Institute provides an detailed comparison of the status of reactor cores of units 1-3 at Fukushima with TMI.
http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110318.html .
The Safety Culture of the nuclear industry in Japan has also suffered, as suggested by the following article:
Japan Nuclear Disaster Caps Decades of Faked Reports, Accidents
http://www.bloomberg.com/news/2011-03-17/japan-s-nuclear-disaster-caps-decades-of-faked-safety-reports-accidents.html .
“… Tanaka says the vessel was damaged in the production process. He says he knows because he orchestrated the cover-up. When he brought his accusations to the government more than a decade later, he was ignored, he says.
…
In 1990, Tanaka wrote a book called “Why Nuclear Power Is Dangerous” that detailed his experiences. “{out of print but soon to be republished}.
…
“Tokyo Electric in 2002 admitted it had falsified repair reports at nuclear plants for more than two decades. Chairman Hiroshi Araki and President Nobuyama Minami resigned to take responsibility for hundreds of occasions in which the company had submitted false data to the regulator. …”
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