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10+ days of crisis at the Fukushima Daiichi nuclear power plant – 22 March 2010

Update: Detailed graphical status report on each reactor unit is available. Here is the picture for Unit 2 — click on the figure to access the PDF for all units.

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Yes, it really has been that long. So what happened during those 10+ days? For a long answer, look back over the daily posts on this blog, which also has plenty of links to more off-site information. For the short-hand version, I offer you this excellent graphic produced by the Wall Street Journal:

Credit: Wall Street Journal: http://goo.gl/E9YuA

Things continue to develop slowly, but I think now towards an inevitable conclusion — barring any sudden turn of events, a cold shutdown (reactor temperature below 100C) should be achieved in units 1 to 3 within the next week (or two?). The other priority is to get the spent fuel storage sufficiently covered with water to make them approachable (and ideally to get AC power systems restored to these ponds, as has been the case already for units 5 and 6). The clean up, diagnostics, and ultimate decommissioning of Fukushima Daiichi, of course, will take months and years to complete.

What is the latest news?

First, there is a new estimate of the tsunami damage. According to the NEI:

TEPCO believes the tsunami that inundated the Fukushima Daiichi site was 14 meters high, the network said. The design basis tsunami for the site was 5.7 meters, and the reactors and backup power sources were located 10 to 13 meters above sea level. The company reported that the maximum earthquake for which the Fukushima Daiichi plants were designed was magnitude 8. The quake that struck March 11 was magnitude 9.

Second, the IAEA reports elevated levels of radioactivity in the sea water off the coast of these reactors. That is hardly surprising, given that contaminated cooling water would gradually drain off the site — and remember, it is very easy with modern instruments to detect radioactivity in even trace amounts. These reported amounts (see table) are clearly significantly elevated around the plant — but the ocean is rather large, and so the principle of disperse and dilute also applies.

I’m reminded of a quote from James Lovelock in “The Vanishing Face of Gaia” (2008):

In July 2007 an earthquake in Japan shook a nuclear power station enough to cause an automatic shutdown ; the quake was of sufficient severity-over six on the Richter scale-to cause significant structural damage in an average town. The only “nuclear” consequence was the fall of a barrell from a stack of low-level waste that allowed the leak of about 90,000 becquerels of radioactivity. This made front page news in Australia, where it was said that the leak posed a radiation threat to the Sea of Japan.The truth is that about 90,000 becquerels is just twice the amount of natural radioactivity, mostly in the form of potassium, which you and I carry in our bodies. In other words, if we accept this hysterical conclusion, two swimmers in the Sea of Japan would make a radiation threat.

For further details on radiation trends in Japan, read this from WNN. In short, levels are hovering at or just above background levels in most surrounding prefectures, but are elevated in some parts of Fukushima. However, the World Health Organisation:

… backed the Japanese authorities, saying “These recommendations are in line with those based on accepted public health expertise.”

Below is a detailed situation summary of the Fukushima Daiichi site, passed to me by a colleague:

(1) Radioactivity was detected in the sea close to Fukushima-Daiichi. On March 21, TEPCO detected radioactivity in the nearby sea at Fukushima-Daiichi nuclear power station (NPS). TEPCO notified this measurement result to NISA and Fukushima prefecture. TEPCO continues sampling survey at Fukushima-Daiichi NPS, and also at Fukushima-Daini NPS in order to evaluate diffusion from the Fukushima-Daiichi. Though people do not drink seawater directly, TEPCO thinks it important to see how far these radioactivity spread in the sea to assess impact to human body.


Normal values of radioactivity are mostly below detection level, except for tritium. (detection level of Co-60 is 0.02Bq/ml) Also, samples of soil in the station have been sent to JAEA (Japan Atomic Energy Agency).

(2) Seawater injection to the spent fuel pool at Fukushima-Daiichi unit 2. This continues, with seawater injected through Fuel Pool Cooling and Cleanup System (FPC) piping. A temporary tank filled with seawater was connected to FPC, and a pump truck send seawater to the tank, then fire engine pump was used to inject seawater to the pool. Although the water level in the pool is not confirmed, judging from the total amount of injected seawater, 40 tons, it is assumed that the level increased about 30 cm after this operation.

(3) Brown smoke was observed from unit 3 reactor building. At around 3:55 pm on March 21, a TEPCO employee confirmed light gray smoke arising from the southeast side of the rooftop of the Unit 3 building. Workers were told to evacuate. It is observed the smoke has decreased and died out at 6:02pm. TEPCO continues to monitor the site’s immediate surroundings. There was no work and no explosive sound at the time of discovery.

(4) Smoke from unit 2 reactor building (as of 9:00pm, March 21). TEPCO’s unit operator found new smoke spewing from mountain side of unit 2 reactor building around 6:20 pm, which was different smoke from blow-out panel on the sea side. There was no explosive sound heard at the time. At 7:10 pm, TEPCO instructed workers at unit 1 – 4 to evacuate into the building. Evacuation was confirmed at 8:30 pm.

(Note: Since there was another smoke found from unit 3 at 1:55pm and evacuation was completed at that time, no workers were remained at the units when smoke found at unit 2.)

TEPCO assumes the smoke is something like vapor, but are still investigating the cause of this smoke with monitoring plant parameters.

Radiation level near the Gate of Fukushima-Daiichi NPS increased at the time of smoke, then decreased to prior level.

5:40 pm 494 μSv/hr

6:10 pm 1,256 μSv/hr

6:20 pm 1,428 μSv/hr

6:30 pm 1,932 μSv/hr

8:00 pm 493.5 μSv/hr

As a result of smoke from unit 2 and 3, scheduled water cannon spraying operations for March 21 were postponed.

(5) Power supply restoration at unit 2 (as of 5:00 pm, March 21). Power cables have been connected to the main power center (existing plant equipment) and confirmed as properly functioning. Presently, soundness tests of the equipment are underway. A pump motor, which is used to inject water to spent fuel pool, has been identified as needing to be replaced.

Similar power connections have been made to reactors 5 and 6 and a diesel generator is providing power to a cooling pump for the used fuel pools. Power cable is being laid to reactor 4, and power is expected to be restored to reactors 3 and 4 by Tuesday.

Kyodo News now reports that all 6 units are connected to external power, and control room power and lighting is about to be restored.

The water-spraying mission for the No. 4 reactor, meanwhile, was joined by trucks with a concrete squeeze pump and a 50-meter arm confirmed to be capable of pouring water from a higher point after trial runs.

With the new pump trucks arriving, the pumping rates for water spraying has increased to 160 tonnes per hour through a 58 metre flexible boom via remote control.

Here is the latest FEPC status report:

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  • Radiation Levels
    • At 04:30PM (JST) on March 21, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 2,015 micro Sv/hour.
    • At 06:30PM on March 21, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 1,932 micro Sv/hour.
    • Measurement results of ambient dose rate around Fukushima Nuclear Power Station announced at 1:00PM and 4:00PM on March 21 are shown in the attached two PDF files respectively.
    • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.
  • Fukushima Daiichi Unit 1 reactor
    • At 2:25PM on March 21, pressure inside the reactor core: 0.198MPa.
    • At 2:25PM on March 21, water level inside the reactor core: 1.75 meters below the top of the fuel rods.
    • At 2:25PM on March 21, pressure inside the primary containment vessel: 0.16MPaabs.
    • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.
    • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.
  • Fukushima Daiichi Unit 2 reactor
    • At 2:25PM on March 21, pressure inside the reactor core: -0.023MPa.
    • At 2:25PM on March 21, water level inside the reactor core: 1.35 meters below the top of the fuel rods.
    • At 2:25PM on March 21, pressure inside the primary containment vessel: 0.12MPaabs.
    • At 2:25PM on March 21, the temperature of the spent fuel pool: 122.0 degrees Fahrenheit.
    • At 6:22PM on March 21, steam was emitted from the secondary containment building. (Under investigation)
    • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.
    • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.
  • Fukushima Daiichi Unit 3 reactor
    • At 9:30PM on March 20, the Tokyo Fire Department began to shoot water aimed at the spent fuel pool, continuously until 3:58AM on March 21 (roughly 1,137 tons in total).
    • At 12:25PM on March 21, pressure inside the reactor core: -0.083MPa.
    • At 12:25PM on March 21, water level inside the reactor core: 1.6 meters below the top of the fuel rods.
    • At 12:25PM on March 21, pressure inside the primary containment vessel: 0.120MPaabs.
    • At 3:55PM on March 21, gray smoke was emitted from the secondary containment building.
    • At 4:49PM on March 21, the gray smoke changed to white smoke, but the volume of the smoke was unchanged.
    • At 6:02PM on March 21, it was confirmed that the emission of smoke had ceased.
    • As of 4:00PM on March 21, the injection of seawater into the reactor core continues.
    • As of 7:00PM on March 20, about 3,742 tons of water in total has been shot to the spent fuel storage pool.
    • As of 7:00PM on March 21, activities for connecting an external power supply are underway.
  • Fukushima Daiichi Unit 4 reactor
    • At 6:22PM on March 20, 10 Self Defense Force vehicles began to shoot water aimed at the spent fuel pool, until 7:43PM (roughly 81 tons in total).
    • At 6:37AM on March 21, 12 Self Defense Force vehicles and TEPCO began to shoot water aimed at the spent fuel pool, until 8:41AM (in total about 91 tons). TEPCO used one high pressure water cannon supplied by the US Army.
    • As of 7:00PM on March 21, roughly 83 tons of water in total has been shot to the spent fuel storage pool.
    • As of 7:00PM on March 21, activities for connecting an external power supply are underway.
  • Fukushima Daiichi Unit 5 reactor
    • At 4:00PM on March 21, the temperature of the spent fuel pool: 108.1 degrees Fahrenheit.
    • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.
  • Fukushima Daiichi Unit 6 reactor
    • At 7:27PM on March 20: cold shutdown
    • At 4:00PM on March 21, the temperature of the spent fuel pool: 96.8 degrees Fahrenheit.
    • As of 7:00PM on March 21, external power generation is connected and the functionality of the electric devices is being checked.
  • Fukushima Daiichi Common Spent Fuel Pool
    • From 10:37AM to 3:30PM on March 21, roughly 130 tons of water in total has been injected into the spent fuel storage pool.

Our official sources are:

  • Office of The Prime Minister of Japan
  • Nuclear and Industrial Safety Agency (NISA)
  • Tokyo Electric Power Company (TEPCO) Press Releases
  • Ministry of Education, Culture, Sports, Science and Technology (MEXT)

And, to wrap up this report, the the Japan Atomic Industrial Forum has provided their 19th reactor-by-reactor status update (19:00 March 22):

I’ll probably only do a detailed report once every few days now, as things are no longer changing quickly, and we have other issues to start exploring. There’s another reason too — I’m exhausted!

 

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

391 replies on “10+ days of crisis at the Fukushima Daiichi nuclear power plant – 22 March 2010”

“Tokyo (CNN) — Reactors 1 and 2 at Japan’s earthquake-stricken Fukushima Daiichi nuclear power plant suffered more damage from seawater than originally believed and will take more time to repair, the plant’s owner said Tuesday.”

[link deleted -did not support above statement. Please re-submit with the correct link]
What is the current best-case definition of “repair”?

–bks

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TEPCO believes the tsunami that inundated the Fukushima Daiichi site was 14 meters high, the network said. The design basis tsunami for the site was 5.7 meters, and the reactors and backup power sources were located 10 to 13 meters above sea level. The company reported that the maximum earthquake for which the Fukushima Daiichi plants were designed was magnitude 8. The quake that struck March 11 was magnitude 9.

This leaves a rather different impression regarding the design. Early reports seemed to imply that the emergency generators had been foolishly built without protection from a tsunami. This update suggests that they were clearly positioned with a tsunami in mind. Just not one this big.

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bks, I’d think “repair” means bringing back to a system that responds to control and provides a safe working environment. But not operating power reactors.

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Reports that during the periods of grey smoke yesterday/today, site radiation levels spiked to nearly 2000milliSV and personnel were of course withdrawn. When the smoke went away, levels dropped somewhat.

The BBC reported Tepco as speculating the smoke might be from “oil” left by damaged equipment and that the very high rad levels are from a wind change.

I think the only real explanation is that the fuel is moving/settling as the structures are collapsing/warping.

IIRC, the World Trade Centre Towers were discovered to have an expansion rate problem in the steel re-enforcement of the concrete.

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Your cover of this whole affair has been incredible, and makes me wonder how you were able to stay on top of everything that was going on. You certainly deserve your break! ;)

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The seawater reference has made me do a fun calculation.

Chernobyl released an estimated 14 EBq of radioactivity.

The worlds oceans contain a lot of uranium and potassium-40 and other isotopes which are radioactive.

The worlds oceans contain about 15000 EBq of radioactivity.

The world’s oceans contain a THOUSAND Chernobyls worth of radiation.

Think about that next time you go to the beach!

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nmsalgueiro said: You certainly deserve your break! ;)

I fully agree. Many thanks Barry for your wonderful info compiling task.

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I suspect in the coming weeks as the facts, and not the hype, becomes known a lot people will be increasingly coming to the realization that this event speaks in favor of nuclear power, not against.

More than a few people have changed their stance from against or neutral to *pro* nuclear due to Fukushima:

“Why Fukushima made me stop worrying and love nuclear power”
George Monbiot, # guardian.co.uk, Monday 21 March 2011 19.43 GMT

Article excerpt:
“A crappy old plant with inadequate safety features was hit by a monster earthquake and a vast tsunami. The electricity supply failed, knocking out the cooling system. The reactors began to explode and melt down. The disaster exposed a familiar legacy of poor design and corner-cutting. Yet, as far as we know, no one has yet received a lethal dose of radiation.

Some greens have wildly exaggerated the dangers of radioactive pollution. For a clearer view, look at the graphic published by xkcd.com. It shows that the average total dose from the Three Mile Island disaster for someone living within 10 miles of the plant was one 625th of the maximum yearly amount permitted for US radiation workers. This, in turn, is half of the lowest one-year dose clearly linked to an increased cancer risk, which, in its turn, is one 80th of an invariably fatal exposure. I’m not proposing complacency here. I am proposing perspective.”

ParetoJ

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I tried to post this in a previous thread but I guess the discussion has now moved here

This follows a prior discussion regarding these thermal images


red_blue:
“Image of reactor 1 is somewhat disconcerting, because the peak heat areas appear to be above the reactor pressure vessel proper and not the SFP. This could indicate leaks around the top shields or their circumferencial support plugs, but is inconclusive”

@red_ blue

regarding n.1, I have also read that
” TEPCO executive vice president, Sakae Muto, said the core of reactor No.1 was now a worry with its temperature at 380-390 Celsius (715-735 Fahrenheit).
“We need to strive to bring that down a bit,” Muto told a news conference, adding that the reactor was built to run at a temperature of 302 C (575 F).
http://ca.reuters.com/article/topNews/idCATRE72A0SS20110322?pageNumber=1&virtualBrandChannel=0

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Reports that during the periods of grey smoke yesterday/today, site radiation levels spiked to nearly 2000milliSV and personnel were of course withdrawn. When the smoke went away, levels dropped somewhat.

It would be interesting to note where this claimed 2,000 mSv/h was measured and who is the source. All correct site measurements have been done in uSv/h and there was no such spike today or yesterday in TEPCO’s own measurements. The latest data they have posted is 2300 JST (so 1.5 hours old) from the main gate, which is 235.9 uSv/h. The highest spike today was 472.7 uSv/h at 1930 JST.

Last time the mobile unit measure radiation at the high dose rate area (closest temporary monitoring station to the reactors, 500 m distance) north of the office building was yesterday at 1630 JST at which time it was 2015.0 uSv/h.

I think what could be going on is that media monitoring these readings doesn’t understand that the highest measurements from the plant area come from this car that drives between several stations (during the last days only between the main gate and north of the office building) and the difference between the 500 m and 1,000 m measuring stations is one order of magnitude (250 -> 2,500 uSv/h). There is no concern when the car moves from the gate to the north of the office building, you would expect the measurement to increase by x 10 each time the car moves.

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All correct site measurements have been done in uSv/h…

Referring to the standard monitoring system including the car, measurements done by patrols engaged in spray operations or other work have been in the mSv/h range (such as readings taken less than 50 m from the reactor buildings on the west reactor service road).

…you would expect the measurement to increase by x 10 each time the car moves.

Of course, when the car moves back to the main gate from the north of the office building, the dose rate it measures drops to 1/10, but that’s never “newsworthy”.

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I would like to comment on the table Barry has provided above on the radioisotopes in the seawater around the crippled reactors. The one isotope that raises questions is I-132. The half-life of this isotope is only 2.3 hrs. There could not have been any of this left in the fuel. I was initially worried this could indicate fission still occuring in the reactors, but I-132 is being produced by the parent isotope Te-132 which has a half-life of 76.9 hrs, so just over 3 half-lives. I-132 should be approaching equilibrium with Te-132, which means the activity of both are roughly equal, i.e. as much I-132 is being produced from Te-132 as is decaying away. If the Te-132 activity was also measured it would allay any concerns fission is still occuring in the reactors, but the decay chain mechanism is the most likely.

http://www.wolframalpha.com/entities/isotopes/iodine_132/pt/h5/gx/

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nmsalgueiro writes, referring to our host,

Your cover of this whole affair has been incredible

I agree — except for a stylistic nitpick. What Barry has been has been credible. That is why more than half the site’s hits have come in the last ten days.

And come to think of it — who was so desperate to deny me my victory in the million-hit-prediction pool that they triggered that earthquake?

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NHK: The lights are on in the control room at unit 3.

Cyril R, so it sounds like Chernobyl released an enormous amount of radiation. Not very reassuring.

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regarding n.1, I have also read that
” TEPCO executive vice president, Sakae Muto, said the core of reactor No.1 was now a worry with its temperature at 380-390 Celsius (715-735 Fahrenheit).
“We need to strive to bring that down a bit,” Muto told a news conference, adding that the reactor was built to run at a temperature of 302 C (575 F).

That temperature alone should not be a big problem as long as the pressure stays within limits (it’s currently about 1/20 of operating pressure). Also, you would not expect amounts detectable by IR imaging of that temperature to radiate from the thick concrete upper shield (or actually several layers of shield slabs), not even if the reactor was operating.

I think the most reasonable explanation for that temperature reading at that exact spot is that some equipment (most likely parts of the crane) have fallen there and then the roof remains have fallen on top of it, creating kind of a “tent structure”, where the collapsed roof remains are highest at that spot (which is also shifted a little to the west from the center of the reactor pressure vessel top). Any heat buildup under the collapsed roof would concentrate on the highest spots of the collapsed structure geometry. Alternatively, temperature differences can come from variations of thickness of remaining roof material.

Remember that at reactor building 1, the roof top collapsed as a whole on top of the refueling floor, while in buildings 3 and 4 the roof panels were blown completely off and the steel grid structure remained somewhat erect (building 4 almost completely erect and building 3 partially collapsed, but not down to the refueling floor level).

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CNN are reporting at 16:30 GMT that damage to reactors 1 & 2 from seawater corrosion is much more extensive than they had thought.

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If there’s a thousand times more radioactivity in the oceans than Chernobyl released, how does that sound like Chernobyl released a lot of radiation if you are not an unreasonable person?

What is the total amount of radioactivity in Bq that was released by Fukushima?

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David Martin, on 23 March 2011 at 3:08 AM said:

CNN are reporting at 16:30 GMT that damage to reactors 1 & 2 from seawater corrosion is much more extensive than they had thought.

I raised this concern here when I first learned they were injecting seawater into the core. Hot salt water is very corrosive. The heat exchangers and pumps were designed for using de-ionized water. There are going to be many leaks as they circulate this salt water through the system to restore normal cooling. The pumps are likely to seize up. Replacing the pumps and/or heat exchangers will be problematic as they will have radioactive material deposited on them.

Do you have a link for this report?

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Woops in my 1:56 AM post I meant to say:
!
Clearly these show reactor 2 UNdamaged and reactor 4 damaged by an internal explosion.

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‘Earlier Tuesday, Tokyo Electric Vice President Sakae Muto said the No. 1 and No. 2 reactors at the plant suffered more damage from seawater than originally believed and will take more time to repair.

The tsunami that followed the 9.0-magnitude earthquake March 11 damaged electrical components and coolant pumps in units No. 1 and 2. Those are two of the three units now believed to have suffered damage to their reactor cores, Muto said.

Reactor No. 2 suffered more damage than No. 1, and the earliest those parts can be replaced is Wednesday, Muto said. The cause of the damage was unclear, but seawater was pumped in previously to cool the reactors as an emergency measure after the earthquake.’

http://edition.cnn.com/2011/WORLD/asiapcf/03/22/japan.nuclear.reactors/index.html?hpt=T2

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The oceans are huge. One thousand is not that many. Fukushima is nowhere near the league of Chernobyl.

David Martin, I would say that damage to the equipment, like pumps and other machines, may be more extensive than they thought. The reactors themselves are intact, inside their containment and pressure vessels. So to me this means we have to be patient while they replace damaged ancillary equipment.

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TEPCO said emergency generators were located 10 to 13 meters above sea level. They also said that damage due to sea water is more extensive than originally estimated.

Even if the generators were not flooded there was still a problem with sea water wetting any electrical equipment in lower locations. Unlike fresh pure water, the sea water is far more conductive to electricity, hence any electrical equipment wetted with sea water is prone to short circuit and failure, therefore, the electric back up system would most likely fail anyway. Electrical control wiring and electric control equipment is especially sensitive to moisture. Minor failure in electric control system can disable power circuits. The problems in control wiring are very difficult and time consuming to find. No doubt there are serious problems with electric system because it took 8 days to bring in power, they say from 1.5 km away, and restore equipment to working condition and it is not all done yet. Once more, there is evidence that electric back up system is not reliable source of power for emergency reactor cooling.
This did not have to happen if steam driven turbo pumps were used for emergency cooling, utilizing steam from reactor itself. As it stands, the anti nuclear crowd will point out the lack of cooling incident is Fukushima for a long time to come

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seamus, on 23 March 2011 at 3:43 AM said:

The reactors themselves are intact, inside their containment and pressure vessels.

I would say that is incorrect. There is damage. The extent and how much radioactivity may be leaking out is not known. The main source of radioactivity has been from pressure release from the primary containment. This has decreased and hasn’t been done recently, but there are other sources of radioactive release. The SFPs being a primary suspect. See the latest JAIF reactor report.

Click to access ENGNEWS01_1300796691P.pdf

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Another report of interest is JAIF earthquake report No. 23. Tokyo Fire Department has sprayed 3 times the pool capacity of unit 3 SFP. The water is leaking out and going somewhere, probably the ocean. Unless their aim is very bad and they don’t correct it. That they haven’t had to spray as much at unit 4 SFP also indicates they have a serious leak in the pool of unit 3.

Click to access ENGNEWS01_1300796691P.pdf

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Where can I find a heat chart? What I mean is when you shut down a reactor how much heat is left after lets say a week.

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The water is leaking out and going somewhere, probably the ocean. Unless their aim is very bad and they don’t correct it.

At least the videos of the first spraying operations with the ARFF vehicles showed that clearly a large portion of the water was falling outside of the entire reactor building. Even assuming they had improved this (by higher pump power and/or clearing rubble to position the vehicles closer), it would be reasonable to assume that 1/3 of the water getting to the pool is probably the upper limit of their effectiveness.

The concrete pouring vehicle is an entirely different animal, with which almost 100% accuracy to a target the size of the pool even from the level of the damaged roof should be expected.

The ARFF vehicles are designed to fight fires resulting from aircraft accidents and typically spray at distances of less than 10 m against a target that is at the same level (not 30 m higher) with clear line of sight and good illumination even during night and heavy fog/rain etc. Some of them carry airframe penetration nozzles, which are only usable when the vehicle is within about 3 meters from a crashed aircraft.

The remotely operated concrete pour vehicle is designed and operated at these heights and higher, with accuracies of less than meter for where the pour must land.

It’s important to keep in mind the limitations of equipment not designed for this kind of work and personnel who have no experience or training for anything like this. Aiming even the standard ARFF spray accurately from inside the vehicle against a target at the same level and of the shape and size they are trained with, is quite difficult due to the showers created.

They often have to operate them in bursts. First spray some and then look where it lands, correct, spray again, etc. until continuous spray can be maintained. In this case they had very little in terms of gauging effectiveness or in aiming so that most of the flow would land on the pool.

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There has likely been some damage to the exposed fuel rods in the cores (probably the main source of radionuclides), but as far as we know, the reactor vessels are intact, and the torus on #2 has been damaged.

The reason they didn’t spray water on #4 was because there was still some water in the pool (despite irresponsible speculation otherwise), and the SFP at #3 was more urgent. And just because they sprayed more water than capacity on #3 doesn’t necessarily mean there’s a leak. Quite possibly a lot of it didn’t get in the pool, there’s a lot of debris up there. There’s no clear indication of leaks in any of the SFPs. There’s been speculation, but no solid evidence. Without circulation, it seems that evaporation alone is enough to reduce the water level significantly over days. Now that the situation at #3 has improved, they are indeed turning their attention to the SFP at #4.

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One reason I suspect a leak in SFP 3 is that the heat of the fuel in SFP 4 is higher, so evaporation should have been higher in 4, but they concentrated on 3. Maybe there was more sloshing in unit 3 that decreased the level, so there are other mechanisms.

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Mattias Svensson says,

Where can I find a heat chart? What I mean is when you shut down a reactor how much heat is left after lets say a week

There’s one in Luke Weston’s recent guest posting here.

Fission fragments produce little heat per decay, i.e., the sum of such a decay’s beta-ray and gamma-ray energies is small, compared to the energy of the alpha-decay of a fuel nucleus that captures a neutron but does not fission. The fastest-decaying of these that I know of is curium-242, half-life a little over 160 days if I recall, and so for the first few weeks it is reasonably accurate to include only beta-decay energy in the residual power calculation.

This being so, you can use the Untermeyer and Weill rule for that. It says the post-fission-shutdown power ‘t’ seconds after fission stops, as a fraction of average fission power during a run time of ‘T_0’ seconds, is


0.1*
(
(t+10)^(-0.2) - (t+10+T_0)^(-0.2)
- 0.87*
(
(t+20000000)^(-0.2) - (t+20000000+T_0)^(-0.2)

)
)

At 10.5 days, I get this working out as 0.0029. At 12 hours after the earthquake, which I seem to recall is about when the batteries ran out, it was 0.0083.

That is why improvised emergency cooling measures are working better now.

(Anyone going to the Darlington public hearings? Would you like me to go?)

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The above information shows both reator 2 and 3 having neagative core pressures and both have a portion of their fuel rods uncovered. Reactor 2 core has negative 0.023 MPa (negative 3.34 psi) and reator 3 core has negative 0.083 MPa (negative 12.0 psi). With a negative 12 psi the water would be boiling around 140 degrees F and to get such a low pressure it seems to me there would need to be significant cooling/condensation in the process. Even when the power generation system is working normally is it possible to have -12 psi at the condensor end of the turbine, much less in the reator core? Would someone explain? Thanks.

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@cyril “Chernobyl released 14 EBq of radioactivity” is a misleading statement. The satement is basically saying that at the moment of release, there were 14 x 10^18 radioactive decays per second. But most of those decays are from Xenon, Krypton, and Iodine with half lives of hours to weeks. Within a few hours, the decay rate might be down to half that rate. Since the actual process of release was sustained for many hours, what does this even mean? Are two significant digits (14) even warranted? Comparing that radiation level to that in the oceans is meaningless. By the time Chernobyl-sourced radiation made it into the ocean, its decay rate was probably down by at least 2 orders of magnitude. Today, the contribution to the world’s radioactivity of Chernobyl is probably nearer to a millionth of the radioactivity in the oceans than it is to a thousandth.

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Hi!

A lot of not so smart people fled Tokyo immediately by plane. I read that an international flight from Tokyo to America will expose them to roughly 50-100 microsievert, making the radiation from the trip much higher than the radiation in Tokyo.

I am now wondering how high the radiation is from x-ray and security checks at the airports? Could you help?

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G.R.L. Cowan, hydrogen energy fan until ~1996, on 23 March 2011 at 5:21 AM said:

Fission fragments produce little heat per decay

Technically you are talking about fission products. The fission fragments are what are produced at the moment of scission, even before the release of neutrons. These fragments have a kinetic energy of around 190 Mev. That is where most of the energy is released in the fission process. Alpha decay has an energy of around 5 Mev and the beta/gamma decay that happens later is in the 100s of kev range. But there are a lot of them for each fission as the products go down the decay chain to stable isotopes. Did my thesis on predicting fission fragment yield, so that is why I’m nitpicking. ;)

http://www.nucleonica.net/forum/showthread.php?173-Fission-fragments-versus-fission-products-what-is-the-difference

A proposal for using fission fragments directly.

http://en.wikipedia.org/wiki/Fission-fragment_rocket

There is also a reactor “design” with 90 % efficiency

http://en.wikipedia.org/wiki/Fission_fragment_reactor

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What makes no sense to me is that the last temperature reported for pool #4 was 84 degrees C on the 14th, and there were various reports of it boiling, yet based on the infrared it’s claimed pool #4 was only 42 degrees C on the 20th. According to the IAEA and other sources, the decay heat in pool #4 is close to 2 MW, with 1331 assemblies versus a decay heat of 0.25MW and 514 assemblies in pool #3. Yet the infra red shows pool #3 at 62C, and that’s where the bulk of the spraying is going. How likely is it that the SFP would drop 40C spontaneously, especially when it’s the one with by far the most decay heat? If it’s dry, why isn’t it hotter on the infra red? If it’s wet, what’s keeping it cool?

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With all the news focused on the fear coming from low levels of radiation to the public here is one news paper article that uses actual data from Nuclear bomb survivors to show Radiation Doserates actually increasing their lifespan and health. http://www.nationalpost.com/todays-paper/Reactor+victims+will+benefit+studies+show/4480863/story.html

Radiation Hormesis also demonstrated by the medical profession in Japan and supported by technical papers provides support for this from the medical cancer treatment side. this link covers the basics and gives reference to the studies supporting it.
http://www.angelfire.com/mo/radioadaptive/inthorm.html

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Lessons learned from TMI and Chernobyl were actually enacted by the industry. This is the next level of enlightenment for public safety in my opinion.

Some national nuclear safety agencies have already reacted even before IAEA guidance to make preliminary inquiries to their supervised nuclear energy companies about at least the following issues:
– review of design environmental threats and protection measures
– SBO scenarios and extended accident management (beyond DBA) guidance in place
– backup electricity sources, offsite and onsite
– backup coolant sources, offsite and onsite
– interfacing with offsite rescue services, such as the general fire brigade, army and portable electricity generation

Preliminary reports about these issues will probably be release much sooner than even a preliminary accident investigation report to the still ongoing situation in Fukushima.

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“The clean up, diagnostics, and ultimate decommissioning of Fukushima Daiichi, of course, will take months and years to complete”.

Analysis of TMI bottom vessel steel took more than 10 years…

I think generally there is under evaluation of the true impact of this issue.
I. E. the explosion in building 3 was great, probably with damage of the pool with fuel…

We have no data of Sv values on the vertical of buildings.

You Barry are exhausted, I truly understand you. But the fuel is not exhausted, it will work each day, 24 hours per day, for many, many years.

Ciao from Italy

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Barry/David evening,

The issues seem to be alot less than early on in the event. They can logically deal with them as reported or occur now. Final details will take months to come out in factual reports. Facts as known currently, this situation seems to be stabilizing. But maybe that’s purely on my opinion.

Factual impacts and challenges yet seen will be eventually disclosed, unless they involve security effects. Lessons learned will be enacted by the industry, that I am sure of.

It’s actually good to see preliminary figures on beyond the concurrent design basis events that occurred published.

I was somewhat aware of how far this pushed some of them. But without technical documentation to support, was not going to comment.

I also know that doesn’t make people feel good, but it seems to appear the design margins to address the assumed values were conservative and prudent.

Lessons learned from TMI and Chernobyl were actually enacted by the industry. This is the next level of enlightenment for public safety in my opinion.

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“For the short-hand version, I offer you this excellent graphic produced by the _Wall Street Journal_”

Edward Tufte (author of _The Visual Display of Quantitative Information_ and many other incisive works on presentation graphics) would tear that to pieces for its sloppiness.

For one thing, it glaringly and inaccurately depicts the hydrogen explosions as “burst” symbols with a radiation hazard icon inside of the burst.

Thereby implying to the casual or scientifically illiterate reader that a nuclear explosion had occurred, instead of a chemical explosion.

There are about a half dozen other obvious lapses of informationally precise presentation in just that one page. And I’m not even by any means a specialist in that discipline.

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WordPress is now back online after that extended hiatus.

torquewrench, point taken, nothing is perfect. If I want to be picky in return (!) there was a rise in radioactivity following the hydrogen explosions.

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Some further updates:

(1) Atmospheric Radioactivity in Fukushima-Diichi site area TEPCO has reported NISA and Fukushima prefecture on detection of atmospheric radioactivity in Fukushima-Daiichi NPS. TEPCO sampled air on March 19, 20 and 21, then identified radioactivity exceeded the limit for radioactive workers (Japanese law stipulates limit of atmospheric radioactivity concentration for three months average not exceeding 50 mSv even if workers breath this air one year)
Iodine-131 concentration was relatively high, 2.30 times of the limit for March 20 sample and 1.52 times for March 21.
Normal radioactive plume discharge concentration is 5 x 10E -6 Bq/cm3 for Iodine-131. (this value is equivalent to 1mSv if breath the air one year.) We believe this level of radioactive concentration is not an immediate danger, but we will continue to monitor atmospheric radioactivity and workers have already equipped with charcoal mask.

(2) Result of additional radioactive material survey in the seawater around Fukushima-Daiichi NPS On March 21st 2011, radioactive materials were detected from the seawater around the discharge canal (south) of Fukushima Daiichi Nuclear Power Station.
TEPCO had conducted re-sampling survey in the wide range of area to examine the effect of radioactive materials in the seawater. Details are as follows;

(3) Off-Site Power restoration status as of 11:00pm March 22nd

The power restoration work was started around 8:00 am. All the cable installment tasks have been completed by the morning of March 22nd (between 8:00 am and 10:30 am). The soundness test is still under progress. It is difficult for us at this moment to clearly decide when the work will be completed.

Current status:
(Unit 1/2)
Reestablishment of power cable to the existing receiving equipment in Unit 2 building has been completed. Soundness test of the equipment and facilities inside Unit 2 building is under progress. As such, the main control room and other equipment inside have not yet been energized.

(Unit 3/4)
“Connection” of power cable to the temporary receiving equipment on the site has been completed.
At 10:35 am, tests to energize between the temporary receiving equipment and the existing receiving equipment in Unit 4 have been completed. Currently the test has been conducted for the equipment at load side.
Unit 3 main control room recovered power for lighting at 10:43 pm on March 22. The power has not been supplied to equipment in the building.

(Unit 5/6)
Reestablishment of power to the existing receiving equipment in Unit 5 and 6 buildings has been completed. The central control center and Residual Heat Removal system which is necessary to cool the reactor are being energized.

(4)Water spray to 1F-4 spent fuel pool using concrete pumping vehicle.
A concrete pumping vehicle sprayed 150ton seawater to spent fuel pool at unit 4, from 5:17 pm to 8:30 pm on March 22. TEPCO has decided to use this concrete pump for spent fuel cooling on March 18, since then we trained workers for the operation as well as to bring the vehicle to the power station under the severe road conditions due to the quake.
The radiation level around the site was 3.0 – 10.0 mSv/hr.
Though we think the concrete pumping vehicle is very effective, we will continue to take all measures to conduct the restoration work with the cooperation of organizations involved.
A camera was set at the end of the water spray arm. We will assess the status of the pool after the spray this time when we retrieve the camera.

This vehicle is designed to inject concrete at high elevation.
– Width of the vehicle: approximately 2.5m
– Length of the vehicle: approximately 15m
– Weight of the vehicle: approximately 55 tons
– Length of the arm: approximately 58m
– Discharge rate: approximately 0 to 160 tons per hour
– Manufacturer: Putzmeister (Germany)

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By Post Author

G.R.L. Cowan, on 23 March 2011 at 2:28 AM said:[…]

There was a lot of traffic at The Oil Drum during the DH debacle for the same reason. Everyone else was babbling about the oilcano.

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Just looked at Rod Adams “Atomin Insights” blog.
Several days ago, he posted on this blog a topic called “Stop Worrying about Spent Fuel Ponds, Zirconium tubes do not burn”, which was cited by Barry Brooks.

This topic and associated comments have been deleted from “Atomic Insights”. The only thing I can find is:

http://theenergycollective.com/rodadams/53997/stop-worrying-about-spent-fuel-pool-fires-zirconium-tubes-do-not-burn

There you find the following:

Stop Worrying About ‘Spent’ Fuel Pool Fires. Zirconium Tubes Do Not Burn
Tags: earthquakeEnergyjapannuclearNuclear Powerzirconium

comments Posted March 20, 2011 by Rod Adams

The contents of this post were incorrect. I acknowledge the error and apologize.

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“Second, the IAEA reports elevated levels of radioactivity in the sea water off the coast of these reactors. That is hardly surprising, given that contaminated cooling water would gradually drain off the site — and remember, it is very easy with modern instruments to detect radioactivity in even trace amounts. These reported amounts (see table) are clearly significantly elevated around the plant — but the ocean is rather large, and so the principle of disperse and dilute also applies.” Barry Brook.

So “the principle of disperse and dilute also applies”. What kind of scientific proof are you showing to asseverate this fact? That radioactivity dilutes harmlessly in seawater. Because I haven’t seen a link in the text to prove this fact. You censored my previous post (not very polite, by the way) cause I didn’t put links to prove my opinion, so it’s fair you show me now yours.

“At 2:30 p.m. Monday, TEPCO collected 500 milliliters of seawater at a point 100 meters south of the outlet, from which waste liquid is drained into the sea.
A total of 5.066 becquerel of iodine-131 per milliliter was detected, a level 126.7 times more than the yearly limit a person can safely ingest as set by the Nuclear Reactor Regulation Law.
If a person ingested two liters of water at this level of contamination over a three-day period, it would be equivalent to being exposed to an annual dose of radiation according to government-set safety standards, the Nuclear and Industrial Safety Agency said.”
DAILY YOMIURI ONLINE
http://www.yomiuri.co.jp/dy/national/T110322004914.htm

126.7 times the yearly limit is way far of dilution of radioactivity, and add this to tainted vegetables, milk, tap water, dust and rain and I can assure you are going to receive a fair amount of radiation if you stay at Fukushima and surroundings.

I’m going to trust every advocate of nuclear safety at Fukushima if he drinks two litres of that water and eats vegetables and food from there. And I want videotaped proof. :)

As far as I know, not even a high rank government official has put a foot (not to say a Minister or the Prime Minister) on the zone, so I presume it must not be a safe place at all.

Respect “the principle of disperse and dilute also applies”, here it goes a proof that it doesn’t:
“”These aren’t levels of contamination that pose an immediate impact,” said Junko Matsubara, former professor at Yokohama City University. “Should the current level of concentration continue, however, consuming contaminated marine products could have an impact on the health.””
DAILY YOMIURI ONLINE
http://www.yomiuri.co.jp/dy/national/T110322004914.htm

Also,
“What general advice can be given to food consumers and producers in the event of a nuclear emergency?
Many other short-, medium- and long-term actions need to be considered in areas confirmed to be seriously contaminated, such as: […] avoid fishing.”
WORLD HEALTH ORGANIZATION
http://www.who.int/hac/crises/jpn/faqs/en/index7.html

There is something funny about how the Japanese government try to downplay the risks of radioactivity:
“Radioactive materials that exceeded regulation levels have been found in seawater around the endangered Fukushima nuclear plant, but government officials offered reassurances Tuesday they will not have an immediate effect on people’s health.”
THE JAPAN TIMES ONLINE
http://search.japantimes.co.jp/cgi-bin/nn20110323a2.html

So, the regulation levels have been excedeed but there is not an inmediate effect on people’s health. Why the reason of putting a safety level in the first place if it doesn’t matter when it’s surpassed? Cancel the levels! You are safe even it’s surpassed by 127 times! The Japanese government keeps you saying that everything is ok in spite of radioactive food, radioactive tap water, radioactive seawater, radioactive dust, and radioactive rain/snow.

It’s a pity people use common sense and don’t trust the government:
– “Evacuees forced out of their homes by the March 11 earthquake and tsunami have begun a fresh exodus to escape the threat of radioactive fallout from the crippled Fukushima No. 1 nuclear power plant.
At least 21,000 people had left evacuation centers for other prefectures as of Saturday, according to a count by The Asahi Shimbun. Most of the evacuees are from Fukushima Prefecture.”
THE ASAHI SHIMBUN
http://www.asahi.com/english/TKY201103210075.html
– “The institute has been inundated with inquiries on radiation exposure.
More than 1,000 people had called by Saturday, tying up all six telephone lines. Callers included people living in the Kanto region.”
THE ASAHI SHIMBUN
http://www.asahi.com/english/TKY201103210086.html

Even the medical proffesion is running away:
– “About one-third of the hospital’s 108 doctors and 730 nurses are absent. Many of them are believed to have left the city to avoid possible exposure to radiation.”
THE ASAHI SHIMBUN
http://www.asahi.com/english/TKY201103210084.html

Finally, the geniuses at the government are doubting if put a ban on seafood at the zone.
“”Given the current situation, I cannot rule out any possibility (including a ban on seafood), but it is not necessary at the moment,” Edano said. “But it is necessary to collect data from a wider range and firmly continue to have experts analyze them.””
THE JAPAN TIMES ONLINE
http://search.japantimes.co.jp/cgi-bin/nn20110323a2.html

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William Fairholm, thanks for the link about possible sources of leaks from the SFPs. The March 19 post by Dave Lochbaum has some interesting information about how reactor to pool transfers work. He says “In addition, reports from Japan say that the spent fuel pool at reactor Unit 4 is leaking, which further increases the need for additional water.” But the only other reports of this that I can find are articles quoting Lochbaum. For example: “David Lochbaum… suspects water is leaking out of the No. 4 spent fuel pool through a seal that, because of the loss of power, is no longer water tight.” http://www.energycentral.com/generationstorage/nuclear/news/en/19271506/Expert-Browns-Ferry-vulnerable-to-leak-like-Japan-plant

Maybe we’ll find out when the pools are topped off and it’s safer to get in there and see what’s going on.

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“NEWS ADVISORY: No. 2 reactor power repair work halted, 500 millisievert per hr radiation found” 11:13 23 March (JST)

If confirmed, this measurement is the highest spot radiation field dose rate measurement to date for the entire crisis. On the other hand, encountering higher radiation fields inside the reactor and auxiliary buildings should be expected considering all that has happened there. Reactor 2 is also the one where containment damage (at least for the pressure suppression pool) is suspected with supporting evidence, since over a week ago.

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So, the regulation levels have been excedeed but there is not an inmediate effect on people’s health. Why the reason of putting a safety level in the first place if it doesn’t matter when it’s surpassed?

Industrial work safety, food safety, chemical safety and other similar safety regulatory systems work on principles of reducing risks to as low levels as practicable and usually contain high safety margings. The idea is that if there is any exceedance of a norm, there will be sufficient time and other protective measures in place to correct the defiency, _before_ any health effects come observable.

In the case of radiation and especially radionuclide contamination, these safety margings are much higher than in many other fields, for various reasons, such as:

– The most likely effects of radiation is increase of cancer risk, which takes years to many decades to manifest itself and diagnostically is from very difficult to completely impossible to attribute to any given carcinogen at the time of diagnosis, which means, that when the effects are actually realized, it’s too late to do anything about it.

– The risk estimates of extremely low doses (less than the variability of background/natural radiation, which in itself is over 100 times) are based on an untested and untestable theory, which is essentially the worst case estimate used instead of actual knowledge of harmfull effects.

– Hysteria: Because below extremely huge and always fatal doses, it’s impossible to detect radiation by human senses, and consequently radiation as a health risk is a big uknown to the general population, creating much irrational fear of the uknown.

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@Red_Blue.
I was reading your and Barrys comments on previous posts, something on your opnion changed since that?
Is the situation under control? I don’t mean: Everything is okay, and this kind of stuff, but it can’t get worst than it was, right? Sorry about my poor grammar, my main language is japanese.

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Yohak, why the fuss?

There is no need for your long-winded rant. Not only was it unwarranted [excessive language deleted] it also ignores basic truths.

Firstly, to demand that a reference be provided to support the notion that 500ml of water, when mixed with the waters of an ocean, actually dilutes! I am shocked! Indeed, once the dilution factor achieves 128, then all reported isotope concentrations will be below the reporting limit, ie of no interest to the regulatory authorities. So what’s there to worry about?

At that point, your own concerns will become baseless. As per the table at the head of this thread, three limits have been exceeded and publicly reported.

With a half-life of 8 days, the offending isotope will naturally decay by a further factor of 128 in 7*8 = 56 days, after which time you can be doubly assured that no nasty exceedances remain. I have no doubt that assessment of the real world impacts will be reviewed and assessed and talked about for some time to come, but the fact remains, that once the waters have been diluted in the Pacific, there will be no cause for further alarm. There will be no ongoing public health threat and there will be no threat to the food chain.

The only threats after dilution will be those which arise due to incomplete dilution, eg possible uptake in molluscs of certain species, or in aquatic vegetation, and even these will dissipate rapidly with time. I am sure that there are many suitably qualified people who will be involved in ensuring that hypothetical secondary effects are assessed and monitored and that, where doubt exists, actions such as bans on fishing are put in place.

You have added precisely nought to the process of rational assessment, review and response which will ensure that the community’s health will not be damaged through these releases.

Finally, where are your manners? Barry brought these figures to your notice. He explained why he was confident that they would not be of lasting concern. Without Barry’s open and frank attitude, you would not even know that the isotopes had been released. [excessive language deleted]

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To the Moderator:

My contribution, above, includes some content which breaches the rules of fair play on this site.
Sorry for that… delete as appropriate.

I tend to get stroppy when confronted by [excessive language deleted] outbursts. Perhaps I am human. For this, I apologise.
MODERATOR
Just a little trimming needed. :)

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@Red_Blue.
I was reading your and Barrys comments on previous posts, something on your opnion changed since that?

I’m not sure which comments you are referring to. I’ve been cautiously optimistic for almost a week now due to the last major releases of activity on March 16th (with the explosion in unit 4). I think the most likely juncture in this accident development was with those hydrogen explosions obliterating the last barrier (secondary containment) between the cores/spent fuel pools and the environment.

Most SBO, cooling failure, containment failure scenarios end with the hydrogen burn in the secondary containment and the core release fraction (outside of the reactor building) not going up after that. These scenarios assume almost total core melt and reactor pressure vessel failure and do not account for controlled pressure release to prevent PRV or containment vessel failure. Also, these scenarios have a timeframe of about battery life + 7 hours (or in our case 15 hours since SBO), so they are not applicable to the timeframes we have seen in Fukushima.

We don’t yet know enough about the status of the cores to preclude the situation worsening, but it seems now much less likely than a few days after the quake.

Is the situation under control?

In my opinion it’s not yet completely under control, because the cooling of the cores and SFPs is still being maintained by ad hoc extended accident management efforts with completely uknown and unmodelled long term effectiveness.

I think one key problem is the usage of salt water in the PRV. I have seen saturation calculations (which are based on the boil off rates with the assumed decay heat values) that after about 1.5-2 weeks of pumping in seawater, natrium cloride (sea salt) concentrations will reach solidification fractions and further pumping will be impossible until temperatures and pressures will reach PRV failure levels.

As don’t know yet how much outflow there has been or what the condition of the cores are, assessing the salt water concentration risk is very difficult.

Other possible problems are associated with reactor equipment damaged by the initial quake and tsunami as well as the hydrogen explosions, venting of very high pressure steam to the reactor building (possible damage to the air conditioning system ducts, if they have not been reinforced like in the US plants), leakage of seawater from the SFP and reactor cooling operations, etc.

So in summary, it could get quite a bit worse than today with all radiation measurements trending down (no further major releases for several days), but the probability is decreasing with every day there is active and well coordinated work onsite to bring things under control.

We might be able to make better risk evaluations when the control rooms of reactors 1&2 and 3&4 are fully functional with (undamaged) all of the standard and backup instrumentation available.

My understanding is that the remote consoles used for the last week lacked displays for much of the critical data, for reasons unknown. TEPCO has recently reported recovery of PRV temperature readings for example, which is good news for properly adjusting their seawater injection flows (which they have already done also).

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An fascinating quote: ” You can’t reason someone out of a position they didn’t reason themselves into.”

The fascinating thing is it seems to apply to many sides of this discussion.

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Quotes from the latest update from JAIF, discussing some of the issues I just mentioned:

􀁺 TEPCO will conduct test operation for pumps, which are to inject water into the reactor at unit-3. External AC power to the main control room of Unit-3 became available at 13:43 of March 22. (10:55, March 23)
􀁺 Nuclear and Industrial Safety Agency announced in its news briefing held around 10:00 AM on March 23 that the core temperature exceed design value of 302℃ and reached almost 400℃ at Unit-1. Core cooling function was enhanced through increasing number of injection lines, given this situation. (10:55, March 23)
􀁺 The work to recover external AC power for units-1, 2, 3 and 4 of Fukushima Daiichi nuclear power station is in progress. External AC power to the main control room of unit-3 became available at 13:43 of March 22. Now the lights are working in the room and working condition has been improved. Unit-3 is the first unit that external AC power became available among four units which are in severe condition. TEPCO will provide eternal AC power to systems for cooling the reactor and the suppression pool after checking availability of these systems at unit-3. Also the work to connect AC power line to distribution panels for Unit-1, 2 and 4 was accomplished. However, pumps of Unit-1 and 2 for cooling were covered by seawater and maintenance work is necessary for these pumps. (04:15, March 23)
􀁺 The Ministry of Education, Culture, Sports, Science and Technology will expand the area for monitoring radioactive nuclides in seawater to 30km, offshore, given the situation that seawater sample collected surrounding area contains radioactive nuclides in excess of the legal standards. (04:15, March 23)
􀁺 Most meters and gages have been unavailable in the power station since station blackout occurred after the earthquake. Meanwhile, temperature instrument to measure surface of the reactor of unit-1, 2, and 3 was restored and becomes available. (04:15, March 23)

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@Red_Blue
Thanks a lot, seriously, I was really worried about the situation, half of my family still 40km from Daichii Plant.
NHK reports are driving people (without base knowledge about the problem) crazy, and they sound like TEPCO isn’t capable to hold on the situation.
Again, thank you for clarifying all those situation!

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At UTC-5 away from the scene, I’ve been pulling for the engineers and technicians at Fukushima Daiichi.

One concern voiced here by several has been that the use of seawater for reactor or SFP cooling is undesirable due to precipitation, corrosion and damage to components. If this is a significant danger to the overall effort, can someone please explain why fresh water supplies are not being used? Are the volumes required too large to truck in? Is well water unavailable or also a bad choice?

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DrD, on 23 March 2011 at 3:40 PM — I certainly don’t know by this time. At the beginning seawater was probably all that was available. Seawater obviously remains convenient. I’m sure the nuclear operators are aware of the salt buildup problem and switch to fresh water before that adds to the difficulties.

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Thanks a lot, seriously, I was really worried about the situation, half of my family still 40km from Daichii Plant.

Just to make it clear, if my family was there, I would make what ever arrangements were necessary in advance to get them out even if there were no nuclear plant issues, because of the overall situation.

The actual decission to leave on the other hand should be based on credible information and evaluation of the risks and costs of self evacuation compared to the risks of staying. The risk of leaving could be serious due to road conditions and aftershocks (like last night) alone.

It’s interesting to note that there is a small region nort west of the plant about 30-40 km away, where the dose rate has been above levels for sheltering in place (staying inside), but apparently the government has not decided to extend the sheltering area towards this direction on the account of most people self evacuating this low population rural area.

Your family members should have a reasonable amount of time available to leave, if they are 40 km away from the plant and with some means of transport (to a local evacuation center at least) available, because it will take several hours of any possible fallout to reach them, should a major new release of radionuclides take place at the plant.

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@Red-Blue 2:55 PM ” I think one key problem is the usage of salt water in the PRV.”

I agree that this may be a potential key problem. It depends on the details of how sea water injection into the reactors has been managed, and details of the reactor pressure vessel which I don’t have.

I think that sea water is injected into the RPV for cooling core decay heat by generating steam. The steam is vented. Sea water contains about 3.5 wt% salts, mainly NaCl, but many others too. Over time, the sea salts can be concentrated in the sea water that remains in the PRV. At some point, the salt concentration gets so high that salts precipitate as solids possibly plugging PRV internals and fuel assemblies . My back of envelope estimate is 35-50% salt would be the saturated solution at high temperatures.
If the managed sea water injection into the PRV by both venting steam and also pressuring out some concentrated sea water, it would be possible to keep salt concentrations below saturation. This would involve the release of some radioactive water.
Does anybody know how they are managing sea water injection into the PRV’s?

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[comment deleted unsupported hearsay. Link provided in Japanese – please re-submit with reference/link in English]

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MODERATOR
I have been away for several hours and standards are already slipping. Now I am back!
Several comments have been deleted because they were unsupported hearsay designed to alarm people.
BNC is a science blog – please support your comments with references/links.
Incivility/rudeness/ad homs have also started to creep back – they will not be tolerated on BNC.

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Can someone explain to me how they are injecting seawater into the reactors without releasing something? Are they draining and filling? Thanks

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Does anybody know how they are managing sea water injection into the PRV’s?

I haven’t read any word about any pumps or other methods of removing liquid water from the reactors being used.

The quickest access that comes to mind for draining some of the RPV inventory is through the reactor water cleanup system, but I have no idea how hard tapping that line for a new connection and a pump would be in the accident conditions. Probably not very easy. Incidentally, this system could be also used to remove trace amounts of sodium cloride and other salts and impurities from the water, if it had power and was otherwise in working condition.

They probably have spent the manpower and other resources elsewhere. The seawater cooling was most certainly intended as a stopgap until normal cooling systems can be brought back online.

It seems there is still have huge demand/supply disparity of clean or even fresh (low salt) water if they have really injected seawater to cool the external spent fuel storage pond, since decontaminating that will be costly and some damage to fuel rods and equipment might be expected.

Since the water treatment facilities are not designed to work with seawater, any large quantity/reservoir of plant process water tainted with seawater added, is going to further complicate any cleanup effort later. Which means, the would not be doing that if there were any other water sources than seawater available in quantity.

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Much talk about the salt in the seawater, but what about other debris such as sand, shells, rocks, and other minerals; what could their effect be on nozzles, valves, pumps, seals, or other parts in the cooling system once it is brought back online?

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Is this to reading at 20km be believed? If so, please put into context.

http://e.nikkei.com/e/fr/tnks/Nni20110322D22JF571.htm

At least it has a rather big error in geography. It mentions Namie as the point of measure, but Namie is 10 km north of Fukushima Daiichi, not 20 km. It is indeed 20 km north of Fukushima Daini though.

Considering that the highest dose rates measured outside of the 30 km perimeter have been 170 uSv/h (although about a week ago) and that the measurement point 46 actually 20 km away from Daiichi (and about 12 km north west of Namie) read 18 uSv/h at 1110 JST yesterday (a value between most other stations and the previous peak dose rate measuring points further north west), this new 160 uSv/h reading at Namie is not such a clear outlier.

This is a dose rate that would usually require sheltering in place. Namie has been evacuated, so there should not be any concern for the general population and the emergency workers would be able to work there for about a month before exceeding even their normal (not extended rescue work) yearly doses.

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[unsupported hearsay. re-submit with reference/link please]

just kidding ;-)
MODERATOR
re previous post:
Rules are somewhat relaxed on the Open Threads which are for personal opinions etc. Ad hom/incivility is still edited and links, where given, must be relevant to the comment and live. Threads with specific subject matter are more rigourously moderated and must not be off-topic or they will be deleted and the commenter advised to re-submit in the Open Thread. Note this version of WordPress does not enable us to switch comments between threads.

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