Time for a new Open Thread on the Fukushima Daiichi nuclear crisis. Please use this post to put any new comments about the situation (including technical information, situation updates, analysis, questions, reflections, etc.). Note that the Open Threads on BraveNewClimate.com are a general discussion forum; please follow the commenting rules, although the ‘stay on topic’ rule obviously does not apply as strictly here.
For context, below is a brief list of recent events since the previous FD post. (For day-by-day detailed updates, I suggest you follow the ANS Nuclear Cafe news and updates (includes links to official reports like JAIF and TEPCO and news feeds from NHK, NY Times, etc.), see also NEI updates, and other links provided in previous posts.)
1) Fuel melt: Recent analysis suggests that the fuel assemblies in unit 1 were almost completely melted in the days following the March 11 earthquake and tsunami. The ‘corium’ (melted actinide fuel, contained fission products, clad etc.) then dropped to the bottom of the reactor pressure vessel (RPV). It is now suspected that during the initial accident, the fuel rods of Reactor No. 1 could have been fully exposed for up to 17 hours, and the earthquake may have caused some structural damage that led to pipe leakage and other problems, in addition to the severe troubles caused by the extended station blackout following the tsunami (which remains the principal cause of the problems).
The temperature of the RPV is now in the range of 100℃ – 120℃, and so the core (or what remains of it) and RPV are stably cooled. That is, this new information is part of a post mortem analysis of events and timeline of the accident, rather than a trigger for a new urgent crisis.
Despite this, this announcement inevitably led to a whole new wave of speculation (and hype), including rumours alleging “1) “melt down in unit 1 has burned a hole through the bottom of the containment vessel” and 2) “that there was a detonation of the fuel rods & pieces of fuel rods were found two miles from the reactors”.
What is the reality? A close nuclear engineer friend of mine says the following:
There is no evidence that the molten fuel has melted through the bottom of the reactor pressure vessel. The latest TEPCO analyses suggest the molten fuel is submerged in water at the bottom of the pressure vessel. Some TEPCO reports mention about “holes” in the containment vessel. What they mean by “holes” is that the seals on pipe penetrations, etc. may not be leak-tight, and hence steam and/or water leaks out of the vessel.
The second claim is absolutely not true. The site is highly contaminated. The radiation mapping of the site, which has taken more than a dozen surveys (because you can do just a few at a time) indicates the contamination is concentrated in the rubble. The steam vented to the reactor building would have carried along volatilized I and Cs, some of which were condensed onto the walls and surfaces, which then blew up in hydrogen explosion.
The soil sample around the site indicated detection of minute quantities of plutonium (some samples included both Pu-238 and Pu-239, and others just Pu-239). The magnitude was within normal fallout contamination ranges. It is not clear whether these Pu detections indicate they are old contaminations or fresh from Fukushima Daiichi.
2) Restoration roadmap timelines revised: Obviously, the more extensive fuel damage at unit 1 will hamper restoration efforts and set back the site management plans. Workers entering unit 1 to install a new cooling system encountered high radiation levels, although because of of protective gear the workers were only exposed to very little radiation (about 2 mSv). However, the company still expects the damaged units to be stabilized by the end of the year. To quote WNN:
Work has already started on constructing a cover over the damaged reactor building of unit 1 to prevent the spread of radioactive materials. Similar covers for the reactor buildings of units 3 and 4 are now being designed. Unit 2 will not require a cover as the reactor building remains intact.
The current status (17 May) of the roadmap can be read in these 8 diagrams (PDF file).
3) New theory for Unit 4 hydrogen explosion: An apparent contradiction at the unit 4 spent fuel pond was the lack of visual damage of the fuel assessmblies and the difficulty in explaining how radiolysis alone could have evolved so much hydrogen — especially if the fuel was never exposed to air. There is now a new explanation for the source of the fire. TEPCO stated:
The SGTS line of Unit 4 merges into Unit 3 exhaust pipe and it might be a case where hydrogen gas came from Unit 3 flew into Unit 4 reactor building. But this estimation remains presumptive and we have not reached to conclude that the vent operation at Unit 3 caused the explosion at Unit 4. And it is not clear the open/close status of valves in SGTS and when and what amount of hydrogen was generated/ flew in the Unit 4 as of this moment.
Some further details here. This is also a plausible explanation of why the unit 4 storage pool had a low level of radioactivity, and why the two fires extinguished themselves without intervention.
4) Worker death: A sub-contractor at the site has died — he had been working on the drainage system of the centralised radioactive waste store. Tests showed that the worker had not been contaminated with radiation (he was exposed to 0.17 mSv), and he appears to have unfortunately died of a heart attack (he was in his 60s). To underscore: sad as this is, ut is not a radiation-sickness-induced death.
5) Hamaoka Nuclear power plant shutdown: Run by Chubu Electric, Hamaoka may be closed, based on political edict. The site includes four ‘Generation II’ boiling water reactors opened between 1976 and 1993, and a new Advanced BWR (1,200 MWe) opened in 2005 (unit 5). As it turns out, units 1 — 3 may not ever be restarted, and further site reinforcement will be required before units 4 and 5 can resume operating.
But what if Japan decided to retreat from their plans to expand nuclear power to meet 50% of their energy needs by 2030? What would it cost them, in terms of (a) increased emissions of greenhouse gases, and (2) financial alternatives. In a superb analysis, The Breakthrough Institute looked at the possible alternative scenarios in their piece: The Costs of Canceling Japan’s Plans for Nuclear Power.
The bottom line is this: (i) if coal and/or gas is used, emissions will rise 15 to 26% and the cost will be $90 — 150 billion in capital costs and a $17 — 27 billion annual hit in terms of increased imported fuel (coal or LNG); (ii) if attempted with renewables, the cost would range from $330 billion (wind, no storage) to $690 billion (solar, with some generous assumptions, representing a 190-fold increase in installed capacity). I’m reminded of what George Monbiot said recently, “The Lost World“:
The case against abandoning nuclear power, for example, is a simple one: it will be replaced either by fossil fuels or by renewables which would otherwise have replaced fossil fuels. In either circumstance, greenhouse gases, other forms of destruction and human deaths and injuries all rise.
Which do you want, folks? If you care about climate change mitigation and clean, reliable and cost-effective power, then it’s time to get real about nuclear energy.
Brave New Climate 
290 replies on “Fukushima Daiichi Open and Update Thread #6”
Which do we want? What will the people of Australia decide? The majority don’t want nuclear. Even with an education campaign I can’t see the Australian public changing their minds.
Can nuclear be forced on the people? I hope so.
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Not as long as fossil fuel industry continues using their right to employ money-amplified free speech to persuade the world that man cannot possibly change the world’s climate and that continued use of their products is mankind’s wisest course of action.
As well drummed-up concerns about nuclear safety because of exaggerated news accounts of the damage inflicted by the Three Mile Island/Chernobyl accidents, along with the dramaturgy wrought by Hollywood, have allowed fear mongering to prevail over sound science.
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Where are the statistics to prove that sentiment, AnotherWorld?
This article says that there is a plurality, but not an outright majority supporting nuclear power:
html
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Sorry, here’s the article: http://www.smh.com.au/environment/one-in-two-favours-using-nuclear-power-to-reduce-pollution-20091012-gtyq.html
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Increasingly, it seems the choice is between fossil fuels and nuclear. Your point is a very good one, Barry, that every MW of renewables used to replace nuclear is a MW of fossil that keeps on burning.
Given the paranoia existing in the general populace about nuclear, and the difficulty in educating same about the very real threat posed by global warming (thanks in no small part to the efforts of the fossil fuel industry), I come to the following conclusion:
We’re screwed.
Or more to the point: our children & grandchildren are screwed.
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The possibility of H2 backflowing from R3 into R4 bdlg was discussed in a March 20th thread (see below). I thought it was unlikely at the time.
The only way (that I can think of) that R3 vent vapors to a common stack could backflow into R4 is if the common line at the R3/R4 junction to the stack was blocked. (See sketch in article) Only if this is the case, could pressure build to backflow into R4. Otherwise, the path of least resistance is up the stack. The common line could be examined to see if it is blocked.
March 20 comments
“As far as R3 vent vapors going to common vent stack and then backflowing to R4 and ending up in the building top, I think that is unlikely. High stacks have chimney draft effect which sucks on both R3 and R4 if common connection”
“@David B Benson 12:42: Isn’t H2 generated from R4 SFP low water and hot fuel assemblies a potential source? Is it probable?, well we at least know that it didn’t come from R4 reactor vessel or primary containment since that had no fuel assemblies. The H2 backflow from R3 (damaged at the time) to R4 via common vent stack seems to me to be unlikely
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anotherworld, see one man’s attempt to change the mind of the public of South Australia: http://decarbonisesa.com/
(disclosure – a friend of mine)
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@Prof. Barry Brook:
Actually, they mean precisely that there are holes in the reactor pressure vessel, created by molten corium.
[Reuters] Fukushima reactor has a hole, leading to leakage
In the WSJ article, manager Matsumoto estimates ~10% of the corium has collapsed into the primary containment vessel, with the remaining 90% still being in the RPV. They say they don’t think the corium has escaped the primary containment, although it does have holes and has leaked thousands of tons of contaminated water. (According to the graphic, the theory is that it is the torus that has failed).
[WSJ] At Reactor, Damage Worse Than Feared
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@uvdiv: Thanks, as I noted in the post, I was reproducing there what my nuclear engineer friend had said — he may or may not be correct, just as Matsumoto may or may not be correct (there are always “may”s in these speculations). The reality, as I know you appreciate, is that none of this can be confirmed or denied in the near future. The leakage of water from either holes or leaks/cracks, is obviously indisputable.
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I’m not so sure that the majority of Australians are against nuclear power.I suspect that the majority of Australians have not thought very much about climate change let alone nuclear power.
How to pay off the mortgage on the McBox in the McBurb without doing without too much else is probably uppermost in their “minds”.Throw in the AFL/ARL scene or some other drug of choice and we have something
close enough to anasthesia.
This is one of the main reasons why we have such (perjorative deleted)incompetents running the country and a set of equal incompetents in waiting for when it is their turn.
I have no idea how this fog of unconsciousness can or will be penetrated,except,perhaps,by a collapse of the system.
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It is certainly regrettable that the current Japanese government has taken fright and made a very silly decision to scale back or abandon nuclear expansion.
However,given the recent history of Japanese politics the current government may not last too long.We can only hope so.
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I was interested in your “political edict” statement regarding the Hamaoka Nuke Plant. At first I thought it was the usual brush it aside statement and then I thought that maybe you have a point.
Looking up geological and historical information I find that the power station is on land that would possibly be affected by liquefaction in the event of a major earthquake. It also lies on top of the Tokai fault. The historical records show that every 100 to 150 years there is a massive earthquake known as the Tokai, with Tsunami. The evidence suggests it is now due. Japan has been supposedly preparing for this since the 70s. In hindsight this powers station looks very vulnerable and with a reasonable chance of an incident soon, this station is the obvious one to pick on. In my opinion the political angle is to try and protect the overall industry by being seen to take action. I think the government needed to show that they are taking a stand and picked on the obvious candidate which has been a focal point for anti-nukes. The fact is that nuclear power stations in the area and in places like Taiwan, West Coast of US are, if you take a rational approach with historical data, potentially are in some danger. My opinion from this is that politics and commerce are the reason why the logical conclusions from historical data and now recent events is suppressed.
See New Scientist for current worries:
http://www.newscientist.com/article/dn619-goodnight-tokyo.html
See wiki for historical data for said earthquake.
http://en.wikipedia.org/wiki/Tokai_earthquakes
One thing I would like to know from the technical guys is what happens to a power station on cold shutdown if it is hit by a major event? Is it completely safe or could you get meltdown if cooling systems stop?
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Barry
But what if Japan decided to retreat from their plans to expand nuclear power to meet 50% of their energy needs by 2030? What would it cost them, in terms of (a) increased emissions of greenhouse gases, and (2) financial alternatives.
Its probably important to distinguish between putting on hold plans to expand nuclear as distinct from either closing down existing nuclear or maintaining existing reactors ( and replacing aging gen II with genIII). I don’t think Japanese Gov is planning to abandon nuclear just not expand further. Most genII reactors will have to be replaced soon in any case.
It is probable that any new reactor not built in Japan is another reactor available to be installed in another country.
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assumptions of Breakthrough Institute
(1) capacity factor of existing nuclear will increase from 72% to 90%(ie similar to US).
(2) renewable alternative using wind assumes wind capacity factor of 20%, BUT DOES NOT assume this increasing to >30% the value of new wind turbines operating in US and Australia..
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The interim findings of the UK inquiry into the implications of the Fukushima accident for current and future nuclear power in the UK have been released. The principle finding:
Click to access interim-report.pdf
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Barry, I would like to see some informed comment on the results of the recent airborne surveys and Cs137 deposition maps for Fukushima region. I think these are important because they represent the real impact going forward. Although I am pro nuclear, I am somewhat concerned by what to me are higher than expected levels of contamination. This will not be a good advertisement for industry. What is the way forward for this area based on Chernobyl experience and what can be done to help clean up?
MODERATOR
It is expected on BNC that links/refs be provided to assist in interpretation of data etc. Could you please supply these for your comment on the “recent airborne surveys….”.
Please ensure future comments follow this BNC commenting policy or your post may be deleted and you will be asked to re-submit including refs.
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@Anonymous moderator:
They are here:
http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/05/10/1304797_0506.pdf
137Cs deposition for quick viewing:
http://i.imgur.com/xu0Pm.jpg
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I am disturbed by the uniting of the accidents at Chernobyl and 3 Mile Island. There were NO releases of radiation from 3 mile. The film on the area fences was not fogged. An anomaly occurred 20 years later ; there were fewer cases of cancer in the surrounding area than in the previous 20 years.
There was a planned release. to the atmosphere which was to regulate pressure in the containment.
The main result was the economic loss of one of the two plants and the scare that the media caused among the people.
Some engineers question the need for the controlled meltdown insisting that the plant was trying to shut down, but NRC was overcautious.
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With regard to Rick’s comment above, there are aerial maps of contaminationhere. The dose going forward from today is negligible according to most of these, for most areas, although that is sometimes hard to discern as the integrated dose starting mid March is used eg. in 18 April slideshow.
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@Rick
They’re removing topsoil from schools, but I don’t know how much that scales:
[Mainicih Shimbun] Fukushima city removing radioactive topsoil in schools
The Chernobyl experience is that areas with Cs-137 deposition above 40 Ci/km^2 (1.48 MBq/m2</sup) are permanent exclusion zones, and will remain so for centuries. This is the red and most of the yellow region in the deposition map — on the order of 1,000 km^2. (Assuming Japan uses the same radiation protection standards as the 1980s USSR).
Chernobyl Cs-137: http://en.wikipedia.org/wiki/File:Chernobyl_radiation_map_1996.svg
Fukushima Cs-137: http://i.imgur.com/xu0Pm.jpg (from http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/05/10/1304797_0506.pdf)
Another Chernobyl finding is that cesium is very slow to migrate physically or chemically (environmental lifetime of 180-320 years) — fallout will stay in place until it decays.
[Wired] Chernobyl Exclusion Zone Radioactive Longer Than Expected
But right now you have slightly over twice as much external dose from Cs-134 than from Cs-137. (Cs-137/Cs-134 activity ratio is about 1.2, and Cs-134 has about 2.7 times more gamma energy per decay than Cs-137). So the dose rates are about three times higher than just the Cs-137 component.
I’m not at all sure what’s going to happen with this fallout contamination. At the very least, several 100 km^2 (around 100,000-200,000 population) will be an exclusion zone. At a more conservative level, for a 10 mSv/year external dose standard (outdoors), you’d evacuate over a million people, until Cs-134 decays. But then that ignores shielding of building walls; indoors dose rates are significantly lower than outdoors.
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@Len R.
Actually there were small radiation releases from Three Mile Island (venting the containment building, mostly noble gases), though of course the doses involved were far smaller than from Fukushima. An average of 0.01 mSv to the two million people in the area, and no higher than 1 mSv (at the site boundary).
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
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> no evidence that the molten fuel has melted
> through the bottom of the reactor pressure vessel
Barry, would you ask your friend what (if anything) _could_ be looked for as evidence either way, on this question?
For example, would melted pressure vessel alloy, or overheated/burning concrete, add detectable trace material into the escaping water or steam, distinct from the material otherwise being vented?
Searching site:nrc.gov turns up many references to
“ex-vessel phenomena (e.g., core concrete interactions)” — but it’s a vast amount of material over 40 years. Your friend might know if this question is answerable, and if so, what they’d be looking for now.
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Do I need to cite what I said above about searching? Here is the search I referred to:
http://www.google.com/search?q=site%3Anrc.gov+core+concrete+interactions
Here’s one example of the results that suggests someone may know the evidence to look for.
“Melt Coolability and Concrete Interaction (MCCI), United States, is an OECD program hosted by the NRC, which studies ex-vessel core-concrete interactions using prototypic materials in a large scale facility.”
http://www.nrc.gov/reading-rm/doc-collections/commission/secys/2009/secy2009-0006/2009-0006scy.html
Hope that’s enough.
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What about the claims that it was the earthquake and not the Tsunami that caused a drop in preassure at reactor #1?
http://www.reuters.com/article/2011/05/16/us-japan-nuclear-idUSTRE74F18020110516
As for Japan replacing their energy production, I would imagine they did a risk analysis and figured it could be cheaper in the long run to go for renewables, its a shame that the technology is not cheap enough to compete with coal and NG, but neither was nuclear, Japan made a concious decision to remain independent from FF because they lack FF, renewables are still Japanese and hopefully they can surpass Germany in terms of green energy, heck they have much much better solar potential just because of seasonal variability
Monthly averages
kWh/m2/day
Japan
1 3.85
2 4.33
3 5.00
4 5.44
5 4.85
6 4.43
7 4.54
8 5.32
9 4.15
10 4.39
11 3.84
12 3.96
Germany (Munich)
1 1.41
2 2.70
3 3.14
4 4.35
5 5.28
6 4.45
7 5.30
8 4.90
9 3.78
10 2.96
11 1.47
12 1.08
http://mapserve3.nrel.gov/PVWatts_Viewer/index.html
As you can see Japan gets more rounded yearly sunlight, unlike Germany that has months when solar output is almost nothing. (Still in awe).
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@Len…it’s not true there was “no release”. There were several releases on purpose with a ‘plume’ of the release traveling southwest to northeast from the plant. They did not appear to cause any health risks albeit anti-nukes dispute this.
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Here’s an IEEE story of March 30 suggesting water samples can help assess whether fuel has escaped the pressure vessel:
http://spectrum.ieee.org/tech-talk/energy/nuclear/nuclear-engineer-says-theres-evidence-fuel-melted-through-reactor-pressure-vessel
“Richard T. Lahey, former chair of nuclear engineering at Rensselaer Polytechnic Institute, in Troy, N.Y., was quoted ….:
… Lahey elaborated on his analysis for IEEE Spectrum ….
… based on the data sources seen by him and colleagues .…
… his best take is that “all cores have melted, and it appears as though Unit 2 has melted through.”
His conclusion about reactor No. 2 comes largely from the amount of radiation in the water found there and the chemical contents of that water….
… where the fuel escapes through the bottom of the chamber, the … molten goop from the reactor—will vaporize the concrete and create dangerous radioactive aerosols. “The water will scrub out the radioactive aerosols” ….
——–
IEEE said they would have followups on this. I did not find them when I searched for them.
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Eric Moore, on 18 May 2011 at 6:12 PM said:
Looking up geological and historical information I find that the power station is on land that would possibly be affected by liquefaction in the event of a major earthquake
Have you actually seen the site specific borehole data?
According to this report studies based on actual boreholes have been done.
Click to access 121501.pdf
The fact is that nuclear power stations in the area and in places like Taiwan, West Coast of US are, if you take a rational approach with historical data, potentially are in some danger.
The US NRC did a Seismic probability risk assessment recently on every operating commercial nuclear reactor in the US.
US NRC Seismic Risk Probability Assessment as published by MSNBC –
http://www.msnbc.msn.com/id/42103936/
No reactor on the West Coast of the US made the ‘Top 10’. Diablo Canyon in California came in at #15 with a 1/23,000 year chance of seismic damage which is somewhat lower then Indian Point in New York with a 1/10,000 year risk.
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following
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Tragedy of the commons!
Until we privatise the emissions of polution via a cap and trade system individuals will continue to utilise fossil fuels at the expense of everyone else. Once people have to pay, then Nuclear will get a big boost in Australia.
Hopefully before then the government doesn’t waste too much money on feel good policy. It’s simple common sense that the impacts from nuclear are wildly over stated but whilst there is no actual cap on emissions, Enviro-religious types will continue to parade around telling us we have sinned and putting subsidised solar panels on their houses, at our expense, and milking guilt money from the public.
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Is it possible that it would be better to stop trying to cool the cores with water in the current circumstances? Can the core material still generate enough heat to cause structural damage? If the core just sat there at several hundred degrees celsius, would this be preferable to continuing to create vast quantities of contaminated water? Any experts here know the answers?
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It appears that the crisis stage of this accident is over and Japan is left with 3 melted down reactors in damaged containments.
Are any plausible estimates now possible of the amount of radioactive material dispersed?
Presumably all of the noble gases are gone, but the iodine and cesium may still be largely in the 100,000 tons of water swamping the plant.
The extent of the long term land abandonment will be determined by this.
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@ Sean . Well said, considering that, it is a complete mystery to me as to why nuclear seems to be political poison.
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@ unclepete Like nuclear, a sensible population policy is also political poison in Australia.
Just put it all down to cognitive dissonance.That seems to be the chief complaint of the polymorons who are runing the show.
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Thanks @uvdiv for supplying link. As I stated I support nuclear but as someone who has been in the uranium business for 25 years, i believe it is important we move beyond the preaching to the converted traps. BLOGs have been wonderful for confirmatory bias. This accident has had an unacceptable consequence in relation to spread of Cs137 in a land poor country. We also know that for a significant part of this crisis winds were offshore. What if they werent? What if winds were northeasterlies? Think about this from a Japanese regulator’s perspective. I believe nuclear is a technology we cant walk away from but we need to take a whole new look at reactor design ( yes I know Gen 3 are better but still require an element of trust if you are a regulator) and how we debate the issue. If you are pro nuke first acknowledge this has been a bad accident with serious long term consequences then build your argument from there.
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> is it possible
Here’s a simulator:
http://www.microsimtech.com/Fukushima.html
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@Rick – you said
I think every energy system requires ‘an element of trust’.
A story on Physorg Radiation protection expert criticizes comparison of Fukushima to Chernobyl summarizes a paper And now, Fukushima in the Journal of Radiological Protection Vol. 31 No. 2. The paper summarizes the accident to date in 11 pages. I don’t think anything in it will be news to BNC regulars.
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Thanks Andrew for links particularly to the wakeford article which is a ripper. Again, from a Japanese regulators perspective you would be gun shy about nuclear if you consider another accident with more persistent on shore winds. To me the hydrogen explosions have contributed to the spread of contaminants. Are there ways to reduce this risk in terms of retro fitting old plants? Also fuel ponds have been overlooked. These have possible contributed a significant amount to NW trending contaminated zone. Would need to check wind directions with accident chronology.
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@etudiant; I’m not calling crisis over yet. The cooling for the three damaged reactors is not looped and the internal status of the reactors is still highly unclear. The spent fuel pools have come off the danger list, although buliding damage is still a possible concern in the event of further earthquakes. So precaution is still a reasonable position.
I don’t really see – under current radioactive dispersion – that there will be any long-term land abandonment. The power plant itself is the most contaminated ground, of course, but that is not likely to spread contamination elsewhere, except the sea. The best use for that land is another couple of reactors!
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Hope I am subscribed?
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“To me the hydrogen explosions have contributed to the spread of contaminants.”
Indeed, the venting of radioactives gases into the environment might be another important source.
I wonder if we could use air balloons to store the radioactive gases (instead of venting into the atmosphere), or some seawater tank to scrub and condensate the gases. Too bad we didn’t have any portable stuff like that [2].
Regarding the hydrogen issue, I am thinking about silicon carbide cladding [1]. That would be so wonderfull. Unfortunately, it might take a while before it happen.
[1] http://web.mit.edu/nse/research/spotlight/kohse_carpenter_sept-2010.html
[1] http://techtv.mit.edu/videos/6190-nse-graduate-poster-session—david-carpenter
[2] Still, the inflatable cover is a good idea, my congrats to tepco ;).
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[…] has a new thread relating to the updates coming out of Fukushima. Some of the information is quite technical. However, the post is easy to read and it is worth […]
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Thank you, Barry!
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The Union of Concerned Scientists posted a scenario of what might have happened to Unit 1 that is different from the experience of Unit 2 and 3.
http://allthingsnuclear.org/post/5582975128/tepco-says-core-of-unit-1-melted
“The water level in Unit 1 is believed to have dropped much faster than for Units 2 and 3.
Why would this have occurred in Unit 1 and not Units 2 and 3? It’s possible it was due to whatever specific damage was caused by the earthquake and tsunami. A recent press story suggests instead that a worker may have shut down Unit 1’s cooling system shortly after the earthquake hit, causing the water to quickly boil away.
But Dave Lochbaum notes that Unit 1 had a different “water makeup system”—which is used to keep water levels where they should be—than Units 2 and 3. Moreover, even if the cooling system had not been shut off by a worker, it would have failed shortly on its own.”
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etudiant, on 19 May 2011 at 4:18 AM said:
Are any plausible estimates now possible of the amount of radioactive material dispersed?
Page 9 of this Tepco summary
Click to access f12np-gaiyou_e_1.pdf
Between 370,000 and 630,000 Tera becquerels is estimated to have been released. Between 6,000 and 12,000 Tera becquerels was cesium.
According to the latest ground monitoring there are still some areas outside the 20km zone with radiation readings in the double digit uSv range.(Monitoring point 83)
Click to access 1306047_051919.pdf
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Simple, unit 1 is older, with less design margin & redundancy. BWRs get simpler and better with newer designs; the ABWR at Hamaoka for example wasn’t particulary bothered by the earthquake.
Newer designs have spray cooling systems for the reactor fuel – so even if the fuel is not covered by water you get to shower it for significant cooling.
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Sharply worded critical editorial complaint about TEPCO’s removal of information on reactor status:
http://www.asahi.com/english/TKY201105180362.html
“… even now, the company does not change its corporate posture that “what is inconvenient should be ignored as much as possible.”
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Venting was the primary cause of radionuclide release; but the hydrogen explosions helped throw them into the wider environment.
Does anyone know more about the venting/stack systems? US BWRs changed the vent path from the top section of the building to a hardened external vent so that even if hydrogen was present and there needed to be venting, there would be no building damage. I would like to know what kind of filters they use for the vent stacks. Carbon filters, resin filters, aqeous acid solution bath scrubbers? I’m quite amazed at the large quantity of cesium that escaped, this should be much lower with good stack filter systems…
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> more about the venting/stack systems
Lots in the news. Distinguish:
— the usual “venting” system that draws air out of the building, through a variety of filters (the system that keeps the whole building at slightly lower air pressure). A proposed alternative “sand filter” was suggested decades ago but never built.
— the emergency “vent” system (direct release, no filters) intended to release pressure from inside the reactor pressure vessel, that failed on all three reactors for several different reasons (tried too late, no power, valves too radioactive to turn manually, valves failed to work).
It’s one for the Cassandra file:
http://blogs.physicstoday.org/newspicks/2011/05/us-warned-on-vents-before-fail.html
The NYT stories have been tracking this almost every day as new news comes out.
http://green.blogs.nytimes.com/2011/05/19/the-importance-of-venting-when-a-reactor-threatens-to-blow-its-stack/?ref=earth
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Search term “nuclear air cleaning” finds much, e.g.
http://www.engineerstalk.com/nuclear-air-cleaning.html/
“… this handbook addresses systems and equipment used in nuclear facilities to capture and control radioactive aerosols and gases…. not intended for application to commercial systems other than for general historical information and discussions of basic air cleaning theory. …
CHAPTER 1 HISTORY OF THE DEVELOPMENT OF AIR CLEANING TECHNOLOGY IN THE NUCLEAR INDUSTRY ….”
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Much, much more out there. The devil is in the details.
http://dx.doi.org/10.1016/0029-5493(90)90286-7
“… concerns that BWR MK I primary containment integrity would be lost should a significant mass of molten debris escape the reactor vessel during a severe accident.
… major factors influencing secondary containment effectiveness include: the mode and location of the primary containment failure, the internal architectural design of the secondary containment, the design of the standby gas treatment system, and the ability of fire protection system sprays to remove suspended aerosols from the the secondary containment atmosphere. Each of these factors interact in a very complex manner to determine secondary containment severe accident mitigation performance.
… plant-specific features that could influence secondary containment severe accident survivability and accident mitigation effectiveness. Current issues surrounding secondary containment performance are discussed ….”
The role of BWR secondary containments in severe accident mitigation: Issues and insights from recent analyses
Oak Ridge National Laboratory
December 1988
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The info that came out is already being obfuscated, so I’d guess we’re not hearing the whole story yet; this article points out some of what’s known but not being discussed:
http://www.tennessean.com/article/20110519/NEWS11/305190043/Touted-upgrades-like-Browns-Ferry-s-failed-Japan
“…. The new information revealed greater-than-suspected damage and disclosed, for instance, repeated attempts to open pressure-release safety valves. Vents remotely did not work, presumably because of the power outage.
At least two attempts were made to open valves manually. But the company data offered no other details ….
The failure of the manual attempts could indicate an even greater breakdown of the system, but Nuclear and Industrial Safety Agency official Yusuke Terasaki would point only to power loss in explaining the venting problem…..”
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Argh. Many bits and pieces surfacing now have details that may change what we thought we knew about the background story and what we thought were facts on which discussion has proceeded.
New Scientist here
http://www.newscientist.com/blogs/shortsharpscience/2011/05/fukushima-valve-failures-led-t.html
has multiple links to many background stories worth reading (links at the New Scientist article) including:
http://www.japansubculture.com/2011/05/tokyo-prosecutor-special-investigation-unit-takes-lead-on-tepco-case-as-new-evidence-contradicts-tepco-claims/
“… There are reports that for several years TEPCO was warned by the original manufacturers to replace the core of the reactor and failed to do so….”
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http://af.reuters.com/article/worldNews/idAFTRE74F17K20110516
“… almost 30 percent more intensity than it [one of the reactors] had been designed to withstand, raising the possibility that key systems were compromised even before a massive tsunami hit …
…. partial data recovered from the crippled Fukushima Daiichi plant showed the ground acceleration during the quake exceeded its design specifications at three of the six reactors.”
They don’t say which three; I’d guess #1, #2, and #3, the oldest ones. It would be interesting to know how the design spec differs for #4 and later reactors.
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Just to make certain it is understood what has to happen for a breech of the containment (most likely to the ground underneath the reactor building and possibly into the ground water in the area-if actually possible… not saying it is)
the fuel has to melt and collect on the bottom of the RPV in sufficient amounts to cause melting of the inches thick stainless steel RPV, then hit thru a foot or more of reinforced concrete?
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The emergency steam venting seemed to work fine; the design flaw was in venting to the top building section. The idea is to hold up radionuclides there, but obviously if there’s hydrogen that provides an explosive hazard. US BWRs have changed the vent path to an external hardened vent so that this is not risked.
If there are no filters on the emergency steam venting stack then that is a serious design flaw. I’m having trouble believing this. A simple aqueous HF scrubber bath for example can remove 99.9+ percent of the cesium. Combine with carbon filters, resin filters and cloth filters gives superiour protection. Shouldn’t be hard to design a filter system that removes 99.99% of cesium and iodine. This is all passive operation – the high pressure steam just passes through the vent line with all its filters on the way out.
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Cyril, where did you find a “design … venting to the top building section” described? I thought that the vents went out above the rooftop — but weren’t used, so hydrogen accumulated because the operators didn’t or couldn’t get the vent system to operate early enough.
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Cyril, did you look at this? (One I didn’t cite earlier). It seems to be the initial request or requirement for US plants to install the hardened vent system:
http://www.nrc.gov/reading-rm/doc-collections/gen-comm/gen-letters/1989/gl89016.html
“… actions should be taken, on a generic basis, to reduce the vulnerability of BWR Mark I containments to severe accident challenges. At the conclusion of the Mark I Containment Performance Improvement Program, the staff identified a number of plant modifications that substantially enhance the plants’ capability to both prevent and mitigate the consequences of severe accidents. The improvements that were recommended include (1) improved hardened wetwell vent capability ….”
Searching on that term:
http://www.google.com/search?q=“hardened+wetwell+vent” finds among much other discussion this on a physicsforum blog:
“The last 2 pages list the important modifications that have been made to the Mark I design over the years, including the hardened vent.”
Click to access Report_-_BWR_Mark_I_Containment_03192011_2.pdf
That doc (search it for “hardened vent”) says the hardened vent leads outside the building.
(Image search on the same string is also useful)
Seems like the hardened vents didn’t work or couldn’t be kept open, and that failure to vent properly and soon let the hydrogen accumulate, as I read the stuff.
Surely someone who actually knows where to look this up will come help point to a real clear factual statement, if one exists yet.
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Argh. The early NYT story
http://www.nytimes.com/cwire/2011/03/25/25climatewire-us-experts-blame-fukushima-1-explosions-and-19903.html
says the ‘hardened vent’ system used fans and pushed gas through the big horizontal pipes outside the reactor buildings, leading to the tall stacks (which were broken as I recall plant photos).
That’s completely different from the other notion I’ve seen that said a hardened vent should go straight up through the building and out through the roof.
I wonder. Anyone got a fact?
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Hank Roberts, on 21 May 2011 at 1:53 AM said:
They don’t say which three; I’d guess #1, #2, and #3, the oldest ones.
Tepco released the motion sensor data. Unit #2 had the highest vertical motion at 300 gal compared to unit 4 at 200 gal.
Same earthquake, a few meters apart, 50% difference in force.
Click to access f12np-gaiyou_e_1.pdf
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@ Neil Howes, on 18 May 2011 at 7:48 PM:
Do you have a reference for your claim that … wind capacity factor of … >30% [is] the value of new wind turbines operating in US and Australia.?
It looks like wishful thinking, to me.
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Harry, do you know — out of the four or six reactors — which ones are the three with the lower rating for earthquake? Do they show how close the actual measured motion was to the design rating for each reactor?
At that PDF you linked May 2011 at 12:39 PM, I see only this:
東京電力株式会社
現在、サーバ障害によって、つながりにくい状況となっております。
皆さまには大変ご迷惑をおかけいたしますが、しばらくお待ちくださいますようお願い申し上げます。
(C)TEPCO
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Anyone know more than atomicpowerreview.com is saying about Unit 3? That site says:
http://atomicpowerreview.blogspot.com/2011/05/fukushima-daiichi-update-friday-evening.html
“… In other news… TEPCO has further increased the rate of water injection to the reactor at No. 3 plant at the Fukushima Daiichi site. TEPCO is now injecting a total of 21 cubic meters per hour to the plant; 9 through the fire extinguishing line and 12 through the feed system. Prior to today, the rate had been 18 cubic meters per hour….
This continuous increase is of interest; also of interest is the injection of 180 kg of boric acid on May 15th from 14:33 through 17:00. Soon after this, there appears on the temperature tracking graphs released by TEPCO a sharp rise in a number of temperatures, particularly those at the top of the RPV but also at least one related to a downstream (tailpiece) temperature reading on a steam relief valve. There was also a drop in RPV indicated water level that this increasing of feed rate has corrected.. the drop in level occurring before the borated water was added. I’m both looking for more details on this and waiting for another TEPCO press release that might mention their thinking.. and their suspicions.”
Question for Barry (for your nuclear expert you menetioned who said he thinks the leaks are probably bad seals) — would the seals be expected to continue to deteriorate over time once they start to leak? Would more of the seals be expected to break down if there’s melted core on the bottom of the RPV?
I’m wondering where the excess water has been going and why adding borate is being done now, and whether they’re stuck pouring more and more water into the leaking system until they can find some other way of cooling things down.
Why not start bringing in liquid nitrogen? Or would that risk cracking from sudden cooling shock?
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Definately do NOT pour liquid nitrogen in!!! Use water. Even with hot water the heat shock is bad enough.
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Hank Roberts, on 22 May 2011 at 4:00 AM said:
Anyone know more than atomicpowerreview.com is saying about Unit 3?
Full temperature data from unit #3 from 5/14 to 5/21, also includes a graph of temps from 3/20
Click to access temp_data_3u-e.pdf
Summary of reactor statuses as of noon 3/21
Click to access table_summary-e.pdf
I would note that the amount of water being pumped thru the fire protection line has been decreased to 6 cubic meter per hour.(12 cubic meters thru the feedwater system) for unit #3
Click to access table_summary-e.pdf
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Thanks Harry, your first link got garbled as posted but this works, removing what looks like extra stuff:
Click to access 11052012_temp_data_3u-e.pdf
I keep wondering where (and when) ‘atomicpowerreview’ gets his info– when it differs from what I find published I wonder if it’s newer, older, or just different.
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> reinforced concrete?
Ah, this has details for Japanese reactor designs going back to Fukushima — noting changes over time. This includes the ground earthquake motion specifications, which have changed over time, and mentions geology details for sites as well.
It’s an image, no text, so you’ll have to look at it:
Click to access 20044504.pdf
Recent advances in concrete containment vessels in Japan (dated 1993)
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Hank Roberts, on 22 May 2011 at 9:17 AM said:
I keep wondering where (and when) ‘atomicpowerreview’ gets his info– when it differs from what I find published I wonder if it’s newer, older, or just different.
The most ‘timely’ information locations keep changing.
IAEA was good for a while, but they only update once a week now and the data is out of date.
NISA was good for a while but was occasionally slow getting the english translations up.
Tepco seems like the most current source( in the last few daysy) but they’ve moved most of the updates from the ‘press release’ page to the Fukushima Status page.
http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html
There are also occasional interesting tidbits under the ‘press handout’ and ‘photos for press’ link pages of the fukushima status page. I.E. The 10,000 cubic meter ‘megafloat’ and the components for a cooling system have arrived.
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My background: engineered 24 years nukes, including 9 like Fukashima ( BWR Mark I), also Mark II and the prototype Mark III, initially in structures then including in systems. I headed the first US dry cask storage facility engineering team and was debriefed, and knew key engineers involved with the TMI and Chernobyl events (One was not an accident, it was blown up to prove to engineers that all those pesky safety systems were nonsense.) I know nothing about Japanese designs.
My judgments: TEPCO’s slow, weak response in the early hours after the quake/tsunami, and the lousy design of the DG emergency systems doomed the plant. I am dumbfounded how little, and uncertain the present level of knowledge is, but it tracks TMI and Chernobyl. After the inevitable management /possibly government purge we will learn more.
My (wild) guess: U1, U2 and U3 have melted cores. The earthquake ripped two primary containments (the steel light bulb and doughnut shaped pressure vessel) open. The U4 spent fuel pool structure was broken by the quake. There is a real danger that a subsequent after shock may (a hated word to nuke engineers) cause catastrophic damage, e.g. drop the U4 spent fuel pool inventory on the ground. Spent fuel is heaver than lead and those pools are crammed with SF. Know that it is hideously lethal, its radioactive energy is barely reduced, only the “tin can” is spent in material properties. Nations who store lots of spent fuel in pools for long periods of time do so because of politics. Earthquakes make pools leak. And wiggle piles of melted fuel, which might cause a uncontrolled critical mass, awake the monster where ever he is.
And a 250 KPH Typhoon would be unkind.
Fukushima is in a meta stable safety condition.
After forty years of engineering, ending in a decade assessing advanced technologies: what is coming, what are the barriers, and when will they be real, I conclude that well engineered, built and operated nukes are vital to mankind’s future development, along with fossil fuels, particularly coal. The green energies always cost too much; they will beggar any nation would attempts base loaded supply. But the real barriers to safe nuclear energy is politics, both corporate and government. Neither convey the truth.
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R.L. Hails, you should distinguish between the higher up spent fuel ponds of older BWRs and below grade pools. The latter don’t break or leak catastrophically under any torment, because they are already below grade. Putting spent fuel pools 20-30 meters plus high up in a building is a serious design flaw. The central spent fuel pool at Fukushima is fine though – its built as it should be, below grade. If we want to keep using higher up spent fuel pools in existing reactors then my engineering advice is that they will need multiple hardened spray cooling connected to standpipes on the ground, so that easy access cooling from the ground is always available. Passive hydrogen recombiners and igniters above the pools and you’re all set for safe operation.
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In response to Cyril R:
The elevation of the spent fuel pool, relative to grade, and the reactor flange, was one of the key decisions in the progression from the Mark I , II, and III designs. Among the several aspects to consider, was the safe transport mode of a spent fuel assembly from the reactor to the pool (horizontal, vertical, or inclined) and the seismic loads of a heavy pool high in the structure. This elevation decision is significantly influenced by the bottom control rod design requirements of BWRs. A core melt down in a BWR is new to mankind, because of this complex geometry.
However, my point was the policy of maintaining a massive inventory in the pools, which were never intended in the original fuel cycle design. The US pools are crammed with spent fuel because the government has breached it’s legal obligation to take the spent inventory. Spent fuel takes several years to cool off, after reactor excitation, and significant pool cooling is required during this time, particularly, as with Fukushima U4, in which a full core was off loaded to permit reactor internal repair work. Japan allows spent fuel reprocessing which is verboten in the US, yet for reasons unknown to me, the plant holds 6,000 + tons of spent fuel in an active earthquake/tsunami zone. That is bad engineering.
I would disagree that seismic forces could never cause a pool to leak, whether elevated or not. From media reports, there is significant concern about the seismic integrity of the U4 spent fuel pool, vulnerable to large after shocks. Some leakage is acceptable in the pool liner design and make up systems, but there is no back up for gross pool failure, at any elevation.
We can not speak of safe operation at Fukushima. They blew safe operation.
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> Japan allows spent fuel reprocessing …
But Japan doesn’t have the technology built.
Some of the reasons for the delay are here as of 2010/10/12:
http://www.asahi.com/english/TKY201010110178.html
“Japan Nuclear Fuel Ltd. has decided to delay the start of full-scale commercial operations at a spent nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture, by two more years to 2012. This, the 18th postponement of the project, will leave it 15 years behind schedule. The plant was originally slated to begin operating in 1997….
…
… The project to develop the fast-breeder reactor needed for the envisioned nuclear fuel cycle was given a lift when the Monju prototype reactor in Fukui Prefecture resumed operations in May, for the first time in 14 years. But it soon encountered problems. It has not even been decided whether the electric power industry or the government will build the demonstration reactor planned as Monju’s successor….”
Google “japan monju” and you’ll find this sort of thing:
http://ex-skf.blogspot.com/2011/03/japans-monju-super-breeder-reactor-had.html
“… Monju was being built by different companies working together, Hitachi, Toshiba, Mitsubishi, Fuji Electric, etc.
When they drew up the spec, Hitachi, where I used to work, would round down 0.5 millimeter. Toshiba and Mitsubishi would round up 0.5 millimeter, Nihon Genken would round down 0.5 milli-meter. It was only 0.5 millimeter, but it made a whole lot of difference when there were 100 different parts that needed to fit together. So the pipes didn’t fit, even though they were exactly to the spec and fit perfectly on the blueprint….”
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And, recent news on the Monju test:
http://mdn.mainichi.jp/mdnnews/national/archive/news/2011/05/11/20110511p2g00m0dm002000c.html
TOKYO (Kyodo) — The Japan Atomic Energy Agency will undertake the work in June of recovering a fallen 3.3-ton device from its prototype fast-breeder reactor Monju… which accidentally fell into the reactor vessel last August, the officials said.
Following recovery of the device which was used for fuel exchange, the agency plans to restore operations at the 280,000-kilowatt nuclear reactor to the pre-mishap level and start a test run of 40 percent output of it by the end of fiscal 2011 through next March….
(Mainichi Japan) May 11, 2011
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> seismic integrity
Here’s the ‘roadmap’ with illustrations for adding bracing to the Unit 4 spent fuel pool:
http://www.tepco.co.jp/en/nu/fukushima-np/f1-roadmap/11043001-e.html
“… we have been evaluating the seismic capacity to confirm the soundness of the building. As the result of the evaluation, we have decided to install support structure under the spent fuel pool to enhance safety of the building.
■Work Overview
– Install steel support under the spent fuel pool to sustain the weight above
– To secure its function, install concrete wall and fill up grout between the concrete wall and the bottom of the spent fuel poll
■Schedule
We are now developing detailed work plan and plan to start the preparation work from early May. Then, we will start the main work from mid-May and complete it at the end of July. We expect to finish the installation of steel support by mid-June. Thereafter, we can anticipate that the load will be decreased….”
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The information, particularly the hyperlinks, from Hank Roberts is both insightful and has parrallels with US experience. He discusses a disaster, the lack of interchangeable piping due to a lack of enforceable national technical standards and a management organization with little or no technical expertise. I point out that a group of high level BP executives was on board the drilling rig in the Gulf of Mexico one year ago, and not one person recognised that they were minutes away from roasting in an inferno. Hanks’ article notes the 18th postponement of a highly technical prototype project, 15 years behind schedule, culiminating in the accidental dropping a 3 ton object into the reactor, and calls for help to retired experts. Some US nukes have worse records. The US DOE spent fuel storage facility, Yucca Mountain, was scheduled to accept shipments in Jan 1998. Built for some $40 Bn, it holds nothing.
I met with experts in reprocessing in the mid 1980s. It is far more complex than rocket science; the experts in the field were the cream of their graduating classes. My guess today: most are dead, or retired. I know many lost their careers. It is not possible to hold a brilliant team together for decades, while producing nothing. Only a buracracy would try. Compare the rate of progress of the technologies among reprocessing, bioengineering, robotics and electronics over the last three decades. Compare the technical talents in top management amoung TEPCO, Microsoft, Google, and the Predator drone operation organizations. How did each organization respond to rapid technical change and risk? Do they exhibit robust technical expertise; is each, “on top of their game”? In plain language,does the current nuclear power industry know what it is doing, e.g. in fuel reprocessing, tsunami protection, or hydrogen explosion systems? It has done very little in several generations. Why would any bright youngest go into this career field? In 1980? 1990? 2000? or 2010? What happens in twenty years, if they do not.
At my level of comprehension of the Japanese culture, this may be the root problem of the Fukushima disaster. Japan is not unique in this societal – technical miasma.
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Nhk News are reporting that Tepco say their records show there was no damage to reactors before the Tsunami struck. Can we trust this assessment?
http://www3.nhk.or.jp/daily/english/23_07.html
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R.L. Hails, my point was not that pools can’t leak, the point was that if the pool is below grade then catastrophic leakage can be prevented; the pool being below grade there’s nothing to rapidly leak away to! Cracks and stuff is still possible, but very easy to deal with that, you can use simple clay packing around the pool for eartquake protection, and everything is always easily accessible from the ground. Plunking in a firehose is all you need to do in a worst case scenario. That’s very hard if the pool is a hundred feet up in the air!!
Holding spent fuel in eartquake zones isn’t bad engineering; its bad engineering itself that leads to trouble. For example the dry casks and central below grade spent fuel pools are fine. They are well engineered.
Putting spent fuel high up in spent fuel pools in the reactor building itself is downright stupid. I’ve talked to a nuclear engineer about it and he said it’s the only thing he disliked about the early GE BWR designs (and he’s a PWR operator mind you!)
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As for the Monju reactor, from what I understand its not a very good design. Oxide fuel, fast reactor sodium coolant. This is not a good combination. Fast reactors that breed need to reprocess their fuel, which is expensive with oxides. You also need fuel that dilates sufficiently upon heating to control fission. Metal fuel or molten fuel would be needed to get that, and also get easier, cheaper reprocessing.
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RL Hails
Thank you for the insights. As well as the ability to maintain technical capability affecting safety performance I also wonder whether there is also a fundamental inability to learn shown in the Fukushima.
A couple of points are of interest to me which your experience might help give an authoritative answer to:
1) Learning from TMI and other US incidents. My understanding is that various modifications were mandated to US installions (redundancy of cooling systems particularly) following TMI, other incidents and a post 9/11 review. Further that these were not implemented at Fukushima. Is this correct, and if so, what’s your belief as to the difference this would have made to the outcome?
2) Hydrogen venting. The current TEPCO hypothesis seems to be that backflow of hydrogen from the emergency vent ex unit three entered unit 4 causing the explosion there. This seems to me to be an absolutely fundamental design error and again, one which has been well understood elsewhere in the nuclear and process industries.
My perspective is that a culture of secrecy and desire to reassure have prevented learning. Fundamental change in the openness of the industry is, I think, required to even make it possible to contemplate a change in public perception.
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On the extent of the evacuation zone.
I’ve struggled to find any authoritative source on the evacuation zone and it’s likely extent in time.
There seem to be differing views on
(i) the extent to which the current levels of (mainly Cs) contamination mean a long term (>1 year) evacuation will be necessary
(ii) whether potential for further releases (“metastable” condition of the plant as referred to above by R L Hails) or current exposure levels are driving the extent of the existing zone.
(iii) Whether there is a realistic case that a very long (>decades) zone will be necessary; by comparison to levels set for Chernobyl this seems potentially possible.
Can anyone provide a link to best sources for this info, and informed comment on it?
thanks
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[…] Update on Japanese Nuclear Crisis Barry Brook, Brave New Climate, 18 May 2011 Cancel reply […]
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Brian touches some excellent points on nuclear disasters. Much of our judgments stem from the TMI experience. The Governor, Richard Thornburgh, faced a novel and agonizing set of decisions, immediately after the accident (a stuck open valve and horrible operator performance) due to bum info. The plant instrumentation, common to US plants, was very precise over a small range. It’s purpose was control. However, the words of the first engineer to enter the control room are seared into my memory; he said it was like entering the cockpit of a 747, at 45,000 ft, looking out and not seeing any wings. What do you do? Nuclear experts were advising the public safety decision maker, screaming that everybody was going to die; others heatedly said there was no problem outside the containment. Thornburgh asked who, in the population is most vulnerable to radiation? Infants in the womb, and babies; both are undergoing most rapid growth. With zero technical knowledge, and national terror, he advised expecting moms, and infants to pull back ten miles. This became dogma, a much debated conflict at Fukushima. The real answer is not to let the crap get out, but if air borne zoomies exist, look at a wind rose. If a typhoon hits those open, or weakened pools, God help Japan. The lethal inventory contains half-lives of 10E6 years. Barring storms, or more quakes, they are metastable.
(Cyril R has a very smart friend.)
After TMI, all US plants stuffed (back fitted) redundant wide range instrumentation systems, e,g, to define if the containment was dry, half filled with water, or flooded to the top of the core. We know you can not go in and measure; you must know the plant condition during and after an accident. The ignorance, today, at Fukushima blows my mind. Or the cover up. They appear to be back calculating varying isotopes, of varying half lifes, which must come from a fission reaction, and
“swagging” conditions, just like TMI. But I am ignorant; I do not know what instrumentation exists or is working. I am certain they are under life threatening emotional stress.
One day into the accident, TEPCO had sealed their fate; 80% of their assets vanished, and some $300 Bn in liabilities exist. Had they known ten years ago, would their management decision making been different? Mankind has learned a thousand fold more about subduction quakes, tsunamis, and wide range instrument loops, since U1 was designed. They reportedly took two weeks to string 1/2 mile of power cable to restore plant power. Should a redundant cable have been hung 25 years ago? What was technically decided? By who? What motivated him?
If the peaceful use of nuclear technology is to contribute to society, Brian’s point is axiomatic. It requires brutal honesty of experts, including the open humility to say, “I do not know”, and the political guts to tell voters that all energy can kill, risk will always exist. This requires never ending technical excellence, the highest ethical standards of profit seekers, and politicians, and recognition of those who sustain an advanced way of life. These societal traits, not the complex technology, are the current barriers to “safe” nuclear energy, climate change, and most technical controversies. High voltage is unkind to dumb, greedy people. So is radiation.
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@Brian,
Evacuation Zone
Ground level readings of radiation level inside the 20km zone take on 20 May. They vary from between 0.6 uSv/hr to 95 uSv/hr and while their is some correlation with distance and direction it isn’t a very good correlation.
Click to access 1305391_0521.pdf
Rainy season in Japan is in June and the area is mountainous. There is a possibility of some movement of contamination due to rainwater runoff.
If I was the minister in charge I would wait until after the rainy season before I made decisions about which areas can be re-inhabited without mitigation, which areas will be mitigated and which areas will have long term land use restrictions.
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R. L. Hails, lethal inventory and million year half lives is oxymoron. Isotopes with million year half lives are not very radioactive, and not dangerous to health.
Take iodine-129. It’s radioactive and fission produces a bunch of it, but its long half life makes it, atom for atom, eight hundred million times less radioactive than iodine-131. The difference between dangerous to health and laughable. Worry more about natural uranium in the environment – which is literally everywhere!
People don’t see the difference. Radioactive is radioactive, to them. They don’t know anything actually relevant such as biological uptake and bioconcentration, or the large quantities of natural background radiation that have zero effect on health.
Regarding ‘safety culture’ I don’t like that kind of thinking. People make mistakes. Training and procedures help, but are not foolproof. I much prefer simple, redundant, diverse and passive technical solutions to risks. A diesel generator on the top floor, passive hydrogen recombiners, a hardened external overpressure steam vent with loads of gasket-less carbon filter beds, a two month submarine grade lithium battery system for essential controls and valves, and you’re all set to go.
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As for energy being deadly, this is unfortunately true. But nuclear and hydro are the least deadly (wind requires loads of deadly fossil backup or deadly chemicals and material mining for batteries, making it more deadly than nuclear on the system level). Most importantly burning stuff is extremely deadly. Even biomass is dangerous – an order of magnitude more so than nuclear or hydro.
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Cyril R.
My apologies, a typo with a phone call. strike 10E6, insert 10E5; this error does not change my argument however.
I have witnessed one spent fuel assembly coming out of a transport cask, through ten feet of leaded glass, quickly. The cameras burnt out their electronics and the rad meter pegged at 17,000 R. Death would be certain after a few minutes in that field, although it would take weeks to yield up the spirit.
I led the first US dry cask engineering effort, put the spent fuel in 125 ton garbage cans, nominally 1 foot thick steel and triple sealed, with deep full penetration welds. “Dry” means no heat producing moderator, water. The fuel sits in an inert gas atmosphere to prevent adverse chemical reactions. There are systems which counter act hostile actions which I will not discuss. The alternative approach is to reprocess (repackage the energetic fuel). and reuse it. This back end of the fuel cycle is a political football in the US, and has created a massive societal danger.
I will not quibble buzz words. To allow this lethal material to sit in open pools, or dry casks, scattered about a nation, for generations, is not a safety culture. Fukushima holds circa 6,000 tons, the US inventory is circa 70,000 tons. Most spent fuel should rest in one central below ground tomb, monitored in 3D by advanced surveillance systems, with military might nearby.. To do otherwise is to invite biblical disaster, from skilled enemies. It is lousy technical management, lousy politics, lousy security.
President Roosevelt faced a similar problem when world war was eminent, a fear that the Nazi could steal our scattered gold reserves along the east coast. In ninety days, he moved it inland, and buried it under the fourth armored division, in Fort Knox Kentucky. Not a gram has been disturbed.
I can guess how the decision to place the emergency electrical system below flood level occurred, when at modest cost, it could have been designed above any uncertain flood level. I can guess how an operating DG ran out of fuel since no one filled the tank. I know you can not store emergency electricity in sufficient amounts to control a nuke, I do not understand why a fleet of ships, from one of the largest, most modern ports on earth, Tokyo, did not sail at combat speed to the crippled plant, when hours could have saved everything. Photos the next morning showed an empty shoreline; an armada of fuel/ water tankers, repair shops, and skilled worker accommodations, should have been moored to prearranged berths, everything preplanned, staged, and rehearsed years ago. What is still at risk is a large portion of their nation. With 20-20 hind sight, the technical management decision making at Fukushima has been tardy, inept, and costly. The entire world waited for one concrete pump truck to be air freighted across the Pacific, to that plant, while the pools appeared to be boiling. The robots being used are ad hoc designs developed in New England. These are the droppings that reveal lousy technical management. I do not think it is unique.
Robotics is a game changer in lethal environments. Thousands are used in combat, none are engineered into nuclear power plants (I am not current in this assessment.). The most effective mine field clearer on earth is a 70 ton US main battle tank which is run by a remote joy stick. A variant, engineered for high rad areas, could reduce cesium contaminated soil to a manageable nuisance, but the R&D funding levels are orders of magnitude different between these two dangers.
Nevertheless, properly managed, with talent, and ethics, nuclear power is the technical way to go for modern societies.
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Nonsense, dry modular storage is far more effective and secure than putting the stuff underground in a tomb.
Sometimes you’re not making sense, Hails. 10000 year half life is not dangerous at all, you are referring to the short lived stuff. Yes that must be remotely handled – because of half lives of under 30 years, especially the stuff under 1 year half life yes is dangerous to even look at in the kilograms plus quantities that these are indeed present in spent fuel.
I’m also an environmental and safety engineer. Putting stuff underground is a recipe for disaster – far more than modular dry cask storage which is easy to access at all times. I recommend against all underground waste disposal except for the longest lived radionuclides (they’re not more dangerous than natural uranium that is in the ground). Societies around the world are currently storing dangerous coal ashes in underground mines very primitively, and the coal ash is just as toxic in a million years from now, unlike spent fuel.
The subsoil is not something you go into willingly. It offers no advantage over multiple layers of engineered barriers (stainless steel, steel, reinforced concrete) and there’s always a risk of ground contamination if you build a tombe and abandon it. If you’re uncertain you use more concrete and steel. After about 300 years all of the short lived stuff is gone and you’ve got a goldmine of stable isotopes and high value fissile. Actually I believe we’ll remove the fissile and many other isotopes much earlier than 300 years because we’ll want them so badly to start up Gen IV reactors and for a variety of medical and industrial catalyst applications. I very much doubt we’ll end up waiting even 100 years. We’ll need all the transuranics we can get to start up terrawatts of advanced Gen IV plants.
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As for Biblical disasters, no nuclear even will ever do that. Old spent fuel that sits in a dry cask is just not going to do it. The thermodynamic driving force to throw out radionuclides just isn’t there, and its well protected in multiple layers of stainless steel, carbon steel, and reinforced concrete, all in a simple passively cooled arrangement.
Try continued increased burning of fossil fuels for centuries and you’re much nearer a Biblical event. A hundred years at today’s GhG emissions is about 5 trillion tonnes of CO2 equivalents. Wanna see if that’s Biblical?
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> all of the short lived stuff is gone
But some of it comes back.
[PDF] Transuranic Radionuclides
… the transuranic radionuclides undergo radioactive decay to create typically long chains of decay products….
Click to access transuranics.pdf
That’s why this stuff has to be contained for more than a few centuries. The folks who argue that after 300 years this stuff will be safe are ignoring that.
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No, not ignoring it – the equilibria concentrations are are very small. If it weren’t, natural uranium would be very dangerous. Fissioning actinides away actually reduces the long term radioactivity, because of the decay chain induced actvities you mention. It just doesn’t really matter, after a couple centuries you’d have to eat a lot of it to get killed.
However the U-Pu cycle does make more transuraniums than the Th-U233 cycle, which gives thorium an edge in this respect:
Basically the fission products are the big danger for fresh spent fuel, but they drop below natural uranium rather quickly. Its the transuraniums that give long term activity and hence storage requirement (their decay products are only a minor compounding factor), but fortunately they burn very well in thermal and fast Gen IV reactors such as MSRs and IFRs. This is because they are very heavy elements that are unhappy being so fat.
You do see some bumped up behaviour for the accellerator driven system, which is related to the ingrowth of new nuclides by decay as well as peculiar spallation products forming.
Kirk Sorensen has some nice Java applications on spent fuel and isotope decays.
http://energyfromthorium.com/
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Cyril R.
We are not communicating for several reasons. I am busy but, after forty years of rigorous technical communication which passes over the heads of most decision makers, and readers, I lower the rigor. And rightfully get rocks from technical experts. So be it.
You are both correct and wrong.
The initial concept of the tomb was to store spent fuel in retrievable, controlled geometry dry casks (not buried in pits) and place them in a “permanent” deep underground cavern, a stable mountain. As long as the fuel is stored behind multiple, militarily protected barriers, we are safe. The casks were initially meant to be buffer storage, temporary storage facilities, to accommodate fuel management needs: utilities, and the DOE repository functions. This reasonable approach was trashed, in the US, due to the Yucca Mount fiasco, and vested interests who forced two types of casks (and multiple fuel handling): storage casks, and transport casks. The less you handle fuel, the safer you are.
The policy error is ubiquitous, distributed, long term on-site storage, either in casks or modular storage structures. This is where we are, a very very bad idea. You want a mountain over the casks with a entrance door only our government (or a sane government) controls.
Where we may disagree is the effects of natural, uncontrolled dispersal of spent fuel particles, “fall out”, e.g. driven by a typhoon, over vast land areas, with NO barriers to the environment. Japan, today, is vulnerable from Fukushima, due to its heavy inventory of exposed unprotected spent fuel. The people of Hiroshima and Nagasaki well know the biblical dangers of fall out. ( It is impossible that spent fuel, untreated, could cause an A bomb explosion, but it is quite possible to cause a mess.)
I share your judgment that a different US polity on reprocessing will change the value of this waste to a national resource, aka better than Ft Knox’s gold, within this century. It must be retrievable for that purpose, and would be, sitting in underground casks.
Our discussion on CO2 must wait for another venue. My time is limited.
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RL Hails; Perhaps it’s a lack of imagination, but I don’t see the threat of spent fuel casks. In order to conjure any problem I would have to ignore the nature of the casks and indeed of the fuel. We are not looking at anything that is easily dispersed here, even by significant forces.
Fukushima spent fuel is apparently not as badly protected as was feared; nevertheless, they might well have been better off with more use of casks.
Incidentally – the people of Hiroshima and Nagasaki really didn’t have a significant amount of fallout from their bombs. They were killed by blast, fire, and direct irradiation. Fallout was not a major factor, which is one reason I find the comparison of nuclear power accidents to the fallout from those weapons annoying.
Biblical? as believable as Noah’s flood, I guess… but I fear that discussion would be too far off topic
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Joffan – please supply refs to support your assertions above. Future comments will be deleted without them
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Hello to all, I have been following this blog since the March 11 quake and It has been or great help in providing information about the situation and also by giving opinions from some more in the know when it comes to nuke power. However I fear Japan is headed for another Nuclear disaster in Fukui Prefecture. The Monju power plant is a experimental Fast breeder reactor that has many problems. The latest is the fact that a 3.3 ton machine fell into the reactor during schedule refulling. The company has tried 24 times to revcover the machine without success. The now plan to do something different that I have hear may cause and explosion that in worst case will be a reactor explosion due to the sodium coming into contact with water??. I would be greatful if any on here know or can provide information on the situation at Monju. They began this operation today but there is very little info out there. Thanks in advance.
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John – this is a science blog and as such the policy is to require refs/links to support your comments. Please supply links to your accounts of what is happening at Monju. Further comments without refs may be deleted.
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John, this is the only information currently available:
http://jen.jiji.com/jc/eng?g=eco&k=2011052300541
I’ve never seen any mention of 24 attempts to retrieve the equipment however, and prudent precautions will be used to avoid any sodium-water contact (e.g. inert atmosphere, and the primary loop is not connected to the steam generator anyhow).
That said, Monju is an example of how NOT to pursue a commercial fast reactor, as Cyril noted elsewhere. For a start, the oxide fuel and loop design are just the wrong ways to go for sodium-cooled fast reactors; the US went there, did that (with CRBR and others), and then turned their focus to the metal-fuelled pool-design IFR (EBR-II), which ran flawlessly for 30 years.
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harrywr2
thanks for the link. I’ve seen several such showing the current levels eg MEXT: http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/05/10/1304797_0506.pdf
All this is confused by the different units, which I may have got wrong but here goes.
1) Short Term Exposure
On the MEXT map peak overall exposure levels (red) are 19-91 uSV/hr
According to the NNSA: http://blog.energy.gov/content/situation-japan/
the EPA recommends “public health measures” if the dose exceeds 1000mRem = 10,000uSV over 4 days.
By my calculation, that equates to 100uSv/hr (10,000uSv over 100 hrs)
At that level, “public health measures” are not necessary except perhaps in the red zone on the map.
Which suggests that the exclusion zone is only necessary because of the risk of new emissions rather than existing levels.
2) Longer Term
According to Wikipedia, Chernobyl “Closed Zone” is set at 40 Ci/km2, which (I think) is 1.5e6 Bq/m2
On the MEXT map, Cs 137 peaks (red zone) at 3-14e6 Bq/m2, 80-380 Ci/km2. This is higher than the Chernobyl “closed zone”. Note that the Cs-137 deposit “red zone” is very similar to the overall dose red zone. I guess the choice of ranges leading to this isn’t a coincidence.
Which suggests that, unless my calculations are wrong (entirely possible) there is a real likelihood that a substantial part of the current exclusion zone will be long term uninhabitable, unless levels drop.
These conclusions don’t really seem consistent to me and where this goes seems to me to key to how serious the incident consequences are. I’d appreciate comments from those more knowledgeable than myself as to the errors or otherwise in this analysis.
Can anyone post a link to an authoritative source on this?
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R. L. Hails, with all due respect, we are not communicating because you are wrong on the danger issue. Old spent fuel does not pose any meaningful hazard to future generations; its fresh spent fuel that can be dangerous, but only in horrible designs such as 100 feet high pools with no redundant hardened standpipe connections to spray cool the fuel. This is what Fukushima shows: fresh fuel is potentially dangerous, old fuel in dry casks or below grade pools is very safe.
And while we continue to have the same debates about nuclear safety over and over, 2 million people die every year due to fossil fuel combustion.
You experts aren’t helping by dramatising the situation. Some people say we live in a risk averse society. This is not true. We live in a risk-deluded society.
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Cyril R
“Regarding ‘safety culture’ I don’t like that kind of thinking. People make mistakes. Training and procedures help, but are not foolproof. I much prefer simple, redundant, diverse and passive technical solutions to risks. A diesel generator on the top floor, passive hydrogen recombiners, a hardened external overpressure steam vent with loads of gasket-less carbon filter beds, a two month submarine grade lithium battery system for essential controls and valves, and you’re all set to go.”
I agree with you that inherent safety is preferred and passive systems are better than active.
However, I would absolutely disagree that this obviates the need for a strong safety culture. Without a safety culture learning from other plants will never be implemented to fit such systems (eg Fukushima) and safety systems will not be adequately maintained (eg Buncefield and many, many others). Inherent safety and passive systems are necessary, but not sufficient. Without much more openness from the industry, this safety culture can not be delivered IMHO.
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Hi Barry, and others on the blog.
Thank you for the speedy reply, and to the mod man sorry for not posting links I have added some to the end of this message which confirm what i said in my earlier post. Barry, and others on the blog, what do you think the worst case could be with the work going on at Monju? My wife seems to have found a load of information (in Japanese) that says it is a very dangerous operation they are attempting. (no ref for this as it is what I have been told) I hope the extra information in the links below may help. Thank you
John
links to news articles:
http://www.japantoday.com/category/technology/view/recovery-of-fallen-device-from-monju-reactor-slated-for-june
http://www.nucpros.com/content/equipment-dropped-monju-reactor-vessel-gets-stuck-delaying-restart-plans
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As the 2nd story you linked to said, they are working in an inert argon atmosphere. There is no danger of an accident as the reactor is not operating and there is no water present or anywhere near. However, they may need to drain the sodium if they cannot retrieve the relay cylinder. That is the worst case — that the reactor restart will be delayed again, perhaps for another year (I’ve given up guessing when with Monju). In my honest opinion, the sooner the Japanese close down Monju, dump the loop design and move from oxide to metal fuels, the better. All they need to do is support a PRISM demo. Monju gives them plenty of additional reasons to do this!
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> Old spent fuel does not pose any meaningful hazard
You and Joffan and others keep saying this kind of thing over and over, with no science cite, just PR stuff.
I wonder how it gets by each time it’s repeated.
MODERATOR
You are answering a comment in an Open Thread. Comments Policy is relaxed here, except for personal abuse, so references are not mandatory and personal opinion is tolerated.However, references to the hazards or otherwise of nuclear fuel abound on BNC posts.
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> close down Monju …
> all they need to do is support a PRISM demo
http://www.sciencedirect.com/science/article/pii/S0048733300001086
Entrapment in large technology systems: institutional commitment and power relations
“… embedded commitments can create inertia, causing inferior technologies and technology paths to survive long after they should have been abandoned. This form of technological lock-in may be reinforced when there are close relations between producers and states which prevent markets and democratic processes from operating effectively. These phenomena are illustrated through study of the Thermal Oxide Reprocessing Plant (THORP) — a nuclear reprocessing plant in the UK. The lesson for technology policy is that much more attention needs to be given to the maintenance of reversibility and adaptability in infrastructural development…..”
For a history in detail of how this went wrong, see:
Click to access rr05.pdf
Why think about this in relation to Fukushima?
Reprocessing fuel: http://www.corecumbria.co.uk/newsapp/briefings/briefsmain.asp?StrNewsID=253
“… the rationale for building the plant was predicated on securing a majority of its MOX fuel orders from Japanese utilities. No firm orders from Japan have materialised and none featured in the original order book ….”
and
“… the plant’s process system was too complex to succeed as projected (as admitted by the Secretary of State in 2008 – ‘SMP was based on unproven technology’), … and that hopes of securing large orders from Japan have virtually evaporated as a result of the loss of trust by Japanese utilities following the 1999 MOX falsification scandal.”
Everybody remembers that, right?
There’s a pattern here.
Incompetence, and optimism — a bad combination.
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(Just providing a reference for Joffan’s statement above.)
That’s correct about the fallout, though early direct measurements of radiation due to fallout from the bombs were very fragmentary, and estimates of doses from neutron activation and fallout were actually lacking in major early studies of the bomb survivors until the 1970s.
A comprehensive discussion of the dose estimates due to neutron activation and fallout
can be found in Chapter 6 of US-JAPAN JOINT REASSESSMENT OF ATOMIC BOMB RADIATION DOSIMETRY IN HIROSHIMA AND NAGASAKI: FINAL REPORT and is available here:
http://www.rerf.jp/cgi-bin/frame.cgi?home=ds86a&page=Chapter6
The maximal cumulative radiation dose from fallout integrated from 1 hour after the blasts to infinity
were estimated to be 0.01-0.03 Gy in the area of maximum fallout found to the northwest of Hiroshima and 0.2-0.4 Gy in a small area to the east of Nagasaki.
At the hypocenter, the estimated cumulative dose from neutron activation is estimated to be 0.8 Gy at Hiroshima and 0.3-0.4 Gy at Nagasaki.
The doses from neutron induced radiation are estimated to fall very rapidly with distance from the hypocenter, and they also fall very rapidly in time – some 80% of the induced dose being received on the first day after the explosions and 90% within the first five days.
Since essentially nobody was able to enter the immediate area of the hypocenters on the first day
after the explosion, it is extremely unlikely that anybody received more than 20% of the maximal accumulated dose from neutrons.
In contrast, the maximal estimated doses from direct gamma irradiation, received by people close enough to the hypocenters, but far enough away to survive the blast effects, that is, outside a radius of about 1 km at Hiroshima, were certainly orders of magnitude higher.
(See other chapters of the same work.)
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In brief, to stay on topic and scale a real disaster (scaling nuclear energy is most difficult, even for experts, but is vital).
An Hiroshima event is technically different from the latent danger of Fukushima in that some ~ 95% of bomb effects are released as heat/ radiant energy, perhaps 4% is released as fall out. However these explosions were ~ 1% efficient, and contained ~ 100+ lbs of fuel. (the real numbers are classified, unknown to me). Fukushima can not be a fission bomb, but it can undergo a steam/ hydrogen explosion due to a mis op and/or natural cause. Or hostile action. Pools can be drained and containers can be ruptured, thus removing vital shielding. Uncontrolled airborne releases can be thought of (crudely) as fall out. Power plant spent fuel inventories are orders of magnitude larger than any bomb. These facts are unarguable; they happened/ exist.
The danger of Fukushima is real, present, and can go really bad (my term; biblical). Spent fuel must always be under total control of governmental power. Japan does not have this today.
I have never heard, from any nuclear expert, that, “Old spent fuel does not pose any meaningful hazard to future generations.” If true, it would be the biggest technical breakthrough since Eisenhower’s Atoms for Peace. (You can carry fresh fuel in your pocket; it is harmless until it is excited by the fury of the reactor’s neutron flux.)
No society has properly scaled the risk of nuclear power. Our technical management policies are neither rational, safe, or sustainable. I honor this colloquy.
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