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Fukushima Daiichi crisis – April 1 perspective

The Fukushima Daiichi nuclear crisis has moved off the front page of most newspapers, but a lot continues to happen, and the situation remains unresolved. Below I offer some personal perspectives on some of the things that have been widely reported over the last few days, and then I conclude with some official updates.

Disclaimer: What follows is my interpretation of the sparse and often confusing information being made available by TEPCO, NHK etc. Take or leave at your discretion.

Will the GE Advanced Boiling Water Reactor (a Gen III unit) be built at Fukushima Daiichi to replace units 1-4?

1. Plutonium detected in the soil around the plant. A few isotopes of plutonium (Pu) have been found in soil at various test sites at the FD plant. This has sent some folks on Twitter apoplectic. So where does it come from?

One theory, and quite a reasonable one, is that it is the global residual left over from the extensive atmospheric atomic weapons testing of the 1950s — 1970s. That would help explain the presence of Pu-238, for instance — an isotope not readily created in a power reactor.

Another thought is that there was a local source, either from volatilisation of sloughed material in the drying spent fuel ponds, or perhaps from the reactor cores (that was then carried away in minute traces via the vented steam). Being a heavy metal, however, the Pu would not mobilse readily and would deposit very locally. Remember, Pu is present in all spent fuel, via the U-238 –> Pu-239 transmutation pathway. All reactor fuel elements that have been fissioning will contain plutonium. It is not something peculiar to mixed-oxide (MOX) fuel (which was being used in FD unit 3), as some have implied — there has been a lot of nonsense written about this during the past few weeks.

In short, Pu is a metal, not a demon. Indeed, from my perspective on the Integral Fast Reactor technology, I see Pu as THE fuel of the future, and boldly predict that it will be looked back on, by some far distant civilisation, as among the most important elements humankind ever encountered. However, that’s for another post for another day. But if you want the full review now, please read Cohen.

2. Containment integrity and core damage. The story that hit the headlines was this

Richard T. Lahey, former chair of nuclear engineering at Rensellaer Polytechnic Institute, in Troy, N.Y., was quoted as saying that the evidence he had seen indicated that fuel melted through the pressure vessel of reactor No. 2 at some point after the crisis began. He told The Guardian:

“The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell.”

While I respect his personal opinion as an engineer with professional experience with GE BWRs, I really don’t think he’s correct– to me, as a logical analyst, it’s just not consistent with the recent data. The reactor pressure vessel (RPV) outlet temperature, RPV internal pressure, and drywell pressure readings, have all remained relatively stable over the last few days (see latest FEPC and JAIF reports at the foot of this blog entry). I can’t see that this could possibly have been the case if chunks of molten metal had burned a gaping hole through the 8″ thick steel vessel and then fizzed through the concrete floor to boot. It certainly didn’t happen at TMI-2 in 1979, and I don’t think that it happened at Fukushima unit 2 either. Lahey seems to think his theory is supported by the high radiation readings in the water trench adjacent to unit 2… however, I disagree, as I explain in point 3.

3. Trench water. I think World Nuclear News had done an excellent recap on this: Tsunami likely filled trenches. In short:

Analysis of the trenches at Fukushima Daiichi indicates they were probably flooded by the tsunami. Low radioactivity in one trench may result from capture of radionuclides from the air but high levels in another are unexplained…

…But while an answer appears close on the presence of the water, the levels of radioactivity remain unexplained. The trench at unit 2 is a serious concern due to radiation levels from surface measurement in excess of 1000 millisieverts per hour. Further sampling has not yet taken place due to this extraordinary level, and it is not clear if the dose rate is representative of the whole 6000 cubic metre body of water, although it does match the level in the basement of the turbine building. Unit 2 suffered suspected damage to its torus suppression chamber on the morning of 15 March.

The key to this riddle, I think, is the wetwell torus breech (which is likely to be a pinhole or crack) — there has clearly been damage to containment at unit 2, but NOT, I think, to the RPV. The radioactive water in the trench could also plausibly have come from cracked/burst piping or seals elsewhere in the containment/primary system (remembering that in a BWR, the cooling water/moderator also runs through the turbine directly, unlike in a PWR). But there is no reason to think that this water comes directly from the RPV or drywell (which is where the fuel would be if it had melted through the RPV). Indeed, I think the chances of a large steam explosion at this stage of events — more than two weeks out from the core damage event — is remote in the extreme, and even if this highly unlikely chain of events did occur, it would still not spread reactor fuel over a wide area, because most of the heavier material is very difficult to mobilise  and disperse (remembering that there is no burning graphite in this situation, unlike Chernobyl, and even in that accident most of the actinides stayed put).

The weird theories of Caldicott and her ilk, in which she fantasises about some ‘magical’ mechanism that is able to spread fine particulates of Pu across the landscape and into the lungs of millions of humans, and so (she outrageously claims) render the Japanese islands uninhabitable as a result, is simply beyond a joke (from many angles). Actually, it’s nothing short of appalling, grossly unscientific, hyper-alarmism.

4. Spent fuel ponds. These continue to get serious attention, with regular injections of water. They have likely been the primary source of the Cs-137 releases. The current TEPCO plan is to switch to fresh water injection ASAP. The pools in units 5 and 6 are now stable and both below 40C (see reports given at the end of this post), but there is still some concern of the pools in units 2, 3 and 4 especially. There was even a report that authorities are still considering entombing them in concrete. It’s possible, but I really don’t think that will happen because it may solve a few short-term problems, and create other longer-term site-management headaches (personal judgement).

5. Radation levels in the ocean. These continue to be elevated close to the plant, due presumably to site run-off and the flushing/settling of airborne particles, but drop away rapidly with distance as the isotopes are spread in the ocean waters, as expected. The I-131 has a short half life, and the longer-lived Cs-137 does not bioaccumulate like mercury (for instance). I thought John Bennetts, writing in response to another BNC commenter who had earlier objected vociferously to my rather bland statement about the ‘disperse and dilute’ principle, summed it up rather well:

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, i.e. 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, e.g. 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.

6. Future of Fukushima Daiichi site. TEPCO have announced that units #1 to #4 will be decommissioned once the crisis is finally closed off. Hardly surprising. I said about 2 weeks ago that 1-3 were write-offs, and although unit 4 didn’t have a fuel loading during the accident, the secondary containment has been so badly damaged by the hydrogen fires and problems with the drying spent fuel ponds that it was inevitable that it’d also be curtains. World Nuclear News has more on that story here. The decomm period is likely to take 5-10 years, based on TMI-2 experience (TMI-1 is still running, incidentally), and perhaps longer given the serious problems they’ve had with multiple reactor units. The fate of the undamaged units 5 and 6, which are some 200 m distance from 1-4, remains unresolved. I suspect they’ll eventually be put back into operation, as Japan really needs their electricity, but probably not for 12+ months. From that WNN story, there is also now speculation about whether the slated Gen III units (GE advanced boiling water reactors, similar to those built at Kashiwazaki-Kariwa in the 1990s) will be built on the Fukushima Daiichi site the future:

Tepco had planned to construct two 1380 MWe Advanced Boiling Water Reactors at Fukushima Daiichi and the start of work on these was slated for 2012. This was a delayed date as a result of additional earthquake engineering flowing from what the company learnt during a July 2007 earthquake that hit similar reactors at Kashiwazaki Kariwa. Tepco contracted for 1600 MWe of new coal generation and 4500 MWe of gas to bridge the supply gap.

So, at least that’s clear. Once again, it’s nuclear, or it’s coal and gas.

7. Other useful unofficial posts. Charles Barton from Nuclear Green looks at the good, the bad and the ugly side of reporting on the Fukushima crisis. George Monbiot comments on The double standards of green anti-nuclear opponents (We must apply the same standards to all energy-generating technology as we do to nuclear power). Will Davis, a former U.S. navy reactor operator, has an interesting blog going here: Atomic Power Review, with some informed theories and speculation on what the FD data mean. Worth checking out.

8. Donations to BraveNewClimate. Many people have asked about this, in the comments and privately, and I thank them for their generosity. However, I’ve always maintained that I’d rather pay for the running of the site myself ,on principle. That is, I don’t want to be seen to profit from this venture in any way, because I do it for non-monetary reasons. Indeed, it’s fair to say that I get more than enough reward out of the work by having people read my posts and for them providing a wonderful stream of comments that really makes this blog alive (even if I don’t always agree with them!). That community input makes me feel rich indeed.

(Oh, and I don’t get any $$ from the Google Ads that run — this is how WordPress extracts their pound of flesh for their otherwise largely free [and excellent] hosting service — I just pay them for domain redirection etc.).

———————————

Okay, on to some (semi-) official stuff. The latest IAEA report is here (last updated on 30 March). NEI update status here. Some snips:

At the Fukushima Daiichi site, workers continued to inject fresh water into reactors 1, 2 and 3 to keep them cool, while at the same time dealing with water that has pooled in the basements of turbine buildings and in concrete trenches near the units. As available storage space in the reactors’ condensers is filled, Tokyo Electric Power Co. is looking to store the radioactive water in tanks that will be brought to the facility. TEPCO has switched to fresh water for spraying the spent fuel pools for reactors 1, 2, 3 and 4.

All the units at Daiichi are operating on off-site electric power and work continues to connect equipment. High radiation levels and wet equipment still hampers restoration of the plants’ original machinery.

Here is the latest JAIF status update, as of 2100 on 31 March 2011:

Here are links to the latest reports from the Japanese Nuclear and Industrial Safety Agency (NISA):

Conditions of Fukushima Dai-ichi Nuclear Power Station Unit 1-6(As of 14:00 30th, 2011)

Fukushima Di-ichi Nuclear Power Station Major Parameters of the Plant (As of 14:00, March 30th)

March 30th, 2011 Fukushima Dai-ichi Monitoring points

Finally, the most recent FEPC report:

  • Radiation Levels
    • At 8:51AM (JST) on March 31, it was announced that radioactive nuclide I-131 was detected from the seawater sampled near the seawater discharge point (south side) of Fukushima Daiichi Nuclear Station at 1:55PM on March 30. The level of concentration was approximately 4,385 times higher than the maximum permissible water concentration set by the government.
    • At 2:00PM on March 31, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 157 micro Sv/hour.
    • At 2:00PM on March 31, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 99.9 micro Sv/hour.
    • Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 31 are shown in the attached PDF file. English version is available at:    http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm
    • 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 8:00AM on March 31, pressure inside the reactor core: 0.329MPa.
    • At 8:00AM on March 31, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
    • At 8:00AM on March 31, pressure inside the primary containment vessel: 0.21MPaabs.
    • At 8:00AM on March 31, the temperature of the reactor vessel measured at the water supply nozzle: 480.9 degrees Fahrenheit
    • At 9:20AM on March 31, transferring of the accumulated water at the trench (concrete tunnel which houses pipes and cables) outside the turbine building commenced, until 11:25AM. As a result, the water level at the trench was reduced from 0.14 meters to 1.14 meters below the top of the trench.
    • At 1:03PM on March 31, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete.
    • As of 3:00PM on March 31, the injection of freshwater into the reactor core continues.
    • As of 3:00PM on March 31, preparation to recover and transfer the accumulated water at the turbine building continues.
  • Fukushima Daiichi Unit 2 reactor
    • As of 3:00PM on March 29, the water level at the trench was 1.04 meters below the top of the trench.
    • At 8:00AM on March 31, the temperature of the spent fuel pool: 131 degrees Fahrenheit.
    • At 8:00AM on March 31, pressure inside the reactor core: -0.016MPa.
    • At 8:00AM on March 31, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
    • At 8:00AM on March 31, pressure inside the primary containment vessel: 0.11MPaabs.
    • As of 3:00PM on March 31, the injection of freshwater into the reactor core continues.
    • As of 3:00PM on March 31, approximately 96 tons of water in total has been injected into the spent fuel storage pool.
    • As of 3:00PM on March 31, preparation to recover and transfer the accumulated water at the turbine building continues.
  • Fukushima Daiichi Unit 3 reactor
    • As of 3:00PM on March 29, the water level at the trench was 1.55 meters below the top of the trench.
    • At 9:40AM on March 31, pressure inside the reactor core: 0.016MPa.
    • At 9:40AM on March 31, water level inside the reactor core: 1.85 meters below the top of the fuel rods.
    • At 9:40AM on March 31, pressure inside the primary containment vessel: 0.1066MPaabs.
    • As of 3:00PM on March 31, the injection of freshwater into the reactor core continues.
    • As of 3:00PM on March 31, approximately 4,697 tons of water in total has been shot to the spent fuel storage pool.
    • As of 3:00PM on March 31, preparation to recover and transfer the accumulated water at the turbine building continues.
  • Fukushima Daiichi Unit 4 reactor
    • As of 3:00PM on March 31, approximately 1,098 tons of water in total has been shot to the spent fuel storage pool.
  • Fukushima Daiichi Unit 5 reactor
    • At 11:00AM on March 31, the temperature of the spent fuel pool: 86 degrees Fahrenheit.
  • Fukushima Daiichi Unit 6 reactor
    • At 11:00AM on March 31, the temperature of the spent fuel pool: 78.8 degrees Fahrenheit.
  • Fukushima Daiichi Common Spent Fuel Pool
    • At 8:20AM on March 30, the temperature of the spent fuel pool: 89.6 degrees Fahrenheit.
    • As of 3:00PM on March 31, approximately 130 tons of water in total has been injected to 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)


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.

222 replies on “Fukushima Daiichi crisis – April 1 perspective”

Some good news today. Might help some of the nuclear “worriers” stop worrying about radiation levels.

Japan stops leaks from nuclear plant
Posted 23 minutes ago

Engineers have stopped highly radioactive water leaking into the sea from a crippled Japanese nuclear power plant, a breakthrough in the battle to contain the worst nuclear crisis since Chernobyl.

Here is the full story.
http://www.abc.net.au/news/stories/2011/04/06/3183588.htm?section=justin

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The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
FEPC UPDATE, 6 April:

• Radiation Levels
o The concentration of radioactive nuclides from the seawater sampled at the screen device (installed to remove waste before the intake of seawater) of Unit 2 of Fukushima Daiichi Nuclear Station was as follows:
The details of this report are available at:
http://www.tepco.co.jp/en/press/corp-com/release/11040506-e.html

Nuclides
(half-life) Concentration (Unit : Bq/cm3)
Sampled at 11:50AM on April 2 Sampled at 6:25PM on April 3 Sampled at 9:00AM on April 4 Maximum Permissible Water Concentration
I-131
(8 days) 3.0 x 105 7.9 x 104 2.0 x 105 4.0 x 10-2
Cs-134
(2 years) 1.2 x 105 3.5 x 104 9.6 x 104 6.0 x 10-2
Cs-137
(30 years) 1.2 x 105 3.6 x 104 9.6 x 104 9.0 x 10-2

o At 6:00PM on April 5, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 112 micro Sv/hour.
o At 6:00PM on April 5, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 67.4 micro Sv/hour.
o Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on April 5 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm
o 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
o At 6:00AM on April 5, pressure inside the reactor core: 0.308MPa.
o At 6:00AM on April 5, water level inside the reactor core: 1.7 meters below the top of the fuel rods.
o At 6:00AM on April 5, pressure inside the primary containment vessel: 0.15MPaabs.
o At 6:00AM on April 5, the temperature of the reactor vessel measured at the water supply nozzle: 452.3 degrees Fahrenheit.
o At 7:20AM on April 5, the temperature directly above the spent fuel pool by thermography measurement: 64.4 degrees Fahrenheit.
o At 7:20AM on April 5, the temperature directly above the primary containment vessel by thermography measurement: 78.8 degrees Fahrenheit.
o As of 7:00PM on April 5, the injection of freshwater into the reactor core continues.
o As of 7:00PM on April 5, preparation to recover and transfer the accumulated water at the turbine building continues.
• Fukushima Daiichi Unit 2 reactor
o At 6:00AM on April 5, pressure inside the reactor core: -0.018MPa.
o At 6:00AM on April 5, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
o At 6:00AM on April 5, pressure inside the primary containment vessel: 0.10MPaabs.
o At 6:00AM on April 5, the temperature of the reactor vessel measured at the water supply nozzle: 287.1 degrees Fahrenheit.
o At 6:00AM on April 5, the temperature of the spent fuel pool: 159.8 degrees Fahrenheit.
o At 7:20AM on April 5, the temperature directly above the second containment building by thermography measurement: 82.4 degrees Fahrenheit.
o At 2:15PM on April 5, TEPCO announced that the tracer (white colored dye) was observed entering the ocean through a crack on the lateral surface of the pit (a vertical portion of an underground structure for housing electric cables) near the seawater intake.
o At 3:07PM on April 5, TEPCO began injecting coagulator into the soil around the pit in an attempt to stop the discharge of water.
o As of 7:00PM on April 5, the injection of freshwater into the reactor core continues.
o As of 7:00PM on April 5, preparation to recover and transfer the accumulated water at the turbine building continues.
• Fukushima Daiichi Unit 3 reactor
o At 7:20AM on April 5, the temperature directly above the spent fuel pool by thermography measurement: 132.8 degrees Fahrenheit.
o At 7:20AM on April 5, the temperature directly above the primary containment vessel by thermography measurement: 64.4 degrees Fahrenheit.
o At 10:20AM on April 5, pressure inside the reactor core: 0.005MPa.
o At 10:20AM on April 5, water level inside the reactor core: 1.85 meters below the top of the fuel rods.
o At 10:20AM on April 5, pressure inside the primary containment vessel: 0.1071MPaabs.
o At 10:20AM on April 5, the temperature of the reactor vessel measured at the water supply nozzle: 184.5 degrees Fahrenheit. (This figure is under investigation.)
o As of 1:30PM on April 5, approximately 4,978 tons of water in total has been shot into the spent fuel storage pool.
o As of 7:00PM on April 5, the injection of freshwater into the reactor core continues.
o As of 7:00PM on April 5, preparation to recover and transfer the accumulated water at the turbine building continues.
• Fukushima Daiichi Unit 4 reactor
o At 7:20AM on April 5, the temperature directly above the spent fuel pool by thermography measurement: 122 degrees Fahrenheit.
o At 5:35PM on April 5, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 6:22PM.
• Fukushima Daiichi Unit 5 reactor
o At 1:00PM on April 5, the temperature of the spent fuel pool: 94.6 degrees Fahrenheit.
• Fukushima Daiichi Unit 6 reactor
o At 1:00PM on April 5, the temperature of the spent fuel pool: 81.5 degrees Fahrenheit.
• Fukushima Daiichi Common Spent Fuel Pool
o At 7:10AM on April 5, the temperature of the spent fuel pool: 84.2 degrees Fahrenheit.

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)

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TEPCO Washington Update:

Here are updates on radioactive material release from Fukushima Daiichi NPS and information on IAEA’s visit to the sites.
(1) Outflow of fluid containing radioactive materials to the ocean from areas near intake channel of Fukushima Daiichi NPS Unit 2 (continued report)
(2) Measures taken to stop outflow of radioactive fluid to the ocean from unit 2
(3) IAEA visit to Fukushima Daiichi and Daini NPS

Contacts:
TEPCO Washington Office 202-457-0790
Kenji Matsuo, Director and General Manager
Yuichi Nagano, Deputy General Manager,
Masayuki Yamamoto, Manager, Nuclear Power Programs

(1) Outflow of fluid containing radioactive materials to the ocean from areas near intake channel of Fukushima Daiichi NPS Unit 2 (continued report)

TEPCO detected water containing radiation dose over 1,000 mSv/h in the pit where supply cables are stored near the intake channel of Unit 2 on April 2. Furthermore, we identified a crack about 20 cm on the concrete lateral of the pit, from where the water in the pit was out flowing.

We have implemented sampling of the water in the pit, together with the seawater in front of the bar screen near the pit. These samples were sent to Fukushima Daini Nuclear Power Station for analysis.

Afterward, we implemented sea water sampling at the inside of the pit and in front of the bar screen near the pit. We conducted radionuclide analysis and found radioactive materials. We reported the results to Nuclear and Industrial Safety Agency (NISA), Ministry of Economy, Trade and Industry (METI), and Fukushima prefecture respectively.

We are announcing 3 type of nucleus (Iodine- 131, Cesium-131, and Cesium-137) as definite value at the result of the analysis. In addition, we will re-evaluate other type of nucleus based on the preventive measures under a strong warning of NISA on April 1st (we have reported this yesterday),

(2) Measures taken to stop outflow of radioactive fluid to the ocean from unit 2

In the afternoon on April 3, we injected 20 sets of sawdust (approx 60 kg), 80 sets of polymer (approx 8kg), 3 sets of newspapers and 2.5m3 of water to the trench for power cable of intake channel and stirred.
Afterward, we observed the changes of water level inside the pit and the amount of outflow to the sea. However, as of 9:30, April 5th, we could not observe any changes in the amount of the outflow. Meanwhile, from 7:08 am to 7:11 am, we injected white powder as a tracer from the trench shaft of seawater duct and started a survey for the outflow condition. [Amount of injection: approx 13kg, 20 boxes x 660g/box = 13.2 kg] Currently, we are implementing the water shutoff method of the ground near the screen with the crack surrounding cable duct of the pit. We are injecting materials of water shutoff into the ground to block the outflow channel.

In order to reduce the spread of the radioactive contamination to the sea, we are making efforts to shut the outflow from water intake by installing silt fences and steel sheet piles. Also we will continue to monitor the impact in front of the plant and in the area within 15km from the coast.

(2) IAEA visit to Fukushima Daiichi and Daini NPS

The IAEA plans to dispatch a survey mission to evaluate the incident once the plants are brought into stable condition. The purpose of the visit this time is to observe the situation to prepare for the main survey mission.
The IAEA will conduct visual observation of plants at Fukushima Daiichi NPS and brief opinion exchange with chief of the plants.

They will arrive at Fukushima Daiichi NPS during the afternoon of April 6(Wed). Then, they move to Fukushima Daini NPS and stay one night. In the morning of April 7(Thu), they will observe Fukushima Daini NPS and return to Tokyo.
The IAEA team consists of Mr. Nobuhiro Muroya, Department of Nuclear Safety and Security, Mr. Edward Bradley and Mr. Katsumi Yamada, BWR experts from Department of Nuclear Energy.

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@Ms.Perps

I found the TEPCO press release which says just this:

At 5:38 am on April 6th, we observed the stoppage of the water spilling
from the crack on the concrete lateral of the pit. Details of the
situation will be announced after checking the blockage of the water
flows.

We will continue the countermeasure in order to prevent further outflow
of high level radioactive materials to the ocean.

http://www.tepco.co.jp/en/press/corp-com/release/11040601-e.html

If the radiation was mostly coming from the R2 torus…

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@Barry Brook 6 April 10:37 and elsewhere:

“For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. ”

Barry, I don’t doubt your figure but I think you should say this is the “average” human dose per year. Clearly there are some very large variations in this figure (entirely or at least mostly from natural variation) depending on where one lives. Have you ever seen credible data which provides standard deviation or even 10th and 90th percentiles for this “average” world figure? Alternatively, can you suggest a source for common ranges in natural radiation?

I think it might be useful for everyone to appreciate the natural ranges in order to put the added doses into context .

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@Leigh Bettenay, on 6 April 2011 at 10:59 PM

Barry was just quoting the publicly posted FEPC Update. You can google “FEPC Update” and see the same text posted at many sites.

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Update to Information Sheet Regarding the Tohoku Earthquake
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office

As of 11:30AM (EST), April 6, 2011
• Radiation Levels
o On April 6, TEPCO announced that plutonium 238, 239 and 240 were detected in the soil sampled on March 25 and 28 at Fukushima Daiichi Nuclear Power Station. Concentration of detected plutonium 238, 239 and 240 are the same level of the fallout observed in Japan at the atmospheric nuclear tests in the past, but TEPCO assumes the detected plutonium are attributed to the Fukushima Daiichi Nuclear Power Station, considering the isotope ratio of Plutonium 238 to 239 and 240.
o The concentration of radioactive nuclides from the seawater sampled at the screen device (installed to remove waste before the intake of seawater) of Unit 2 of Fukushima Daiichi Nuclear Station was as follows:

Nuclides
(half-life) Concentration (Unit : Bq/cm3) Ratio
Sampled at 8:00AM on April 5 (a) Maximum Permissible Water Concentration (b) a / b
I-131
(8 days) 1.1 x 104 4.0 x 10-2 280,000
Cs-134
(2 years) 5.5 x 103 6.0 x 10-2 92,000
Cs-137
(30 years) 5.5 x 103 9.0 x 10-2 61,000

o The level of concentration of radioactive nuclide I-131 (1.1 x 101 Bq/cm3) from the seawater sampled near the seawater discharge point of Fukushima Daiichi Nuclear Station at 2:10PM (JST) on April 5 was approximately 280 times higher than the maximum permissible water concentration (4.0 x 10-2 Bq/cm3) set by the government.
o At 7:00PM on April 6, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 82.5 micro Sv/hour.
o Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on April 6 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm
o 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
o On April 6, TEPCO announced that it will start the injection of nitrogen gas into the primary containment vessel at 10:30PM to prevent an explosion by accumulated hydrogen gas.
o At 7:30AM on April 6, the temperature directly above the spent fuel pool by thermography measurement: 75.2 degrees Fahrenheit.
o At 7:30AM on April 6, the temperature directly above the primary containment vessel by thermography measurement: 84.2 degrees Fahrenheit.
o At 12:00PM on April 6, pressure inside the reactor core: 0.313MPa.
o At 12:00PM on April 6, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
o At 12:00PM on April 6, pressure inside the primary containment vessel: 0.15MPaabs.
o At 12:00PM on April 6, the temperature of the reactor vessel measured at the water supply nozzle: 417.2 degrees Fahrenheit.
o As of 2:30PM on April 6, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 2 reactor
o At 5:38AM on April 6, TEPCO confirmed the termination of water leakage into the ocean through a crack on the lateral surface of the pit (a vertical portion of an underground structure for housing electric cables) near the seawater intake.
o At 7:30AM on April 6, the temperature directly above the second containment building by thermography measurement: 89.6 degrees Fahrenheit.
o At 12:00PM on April 6, pressure inside the reactor core: -0.016MPa.
o At 12:00PM on April 6, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
o At 12:00PM on April 6, pressure inside the primary containment vessel: 0.10MPaabs.
o At 12:00PM on April 6, the temperature of the reactor vessel measured at the water supply nozzle: 288.5 degrees Fahrenheit.
o At 12:00PM on April 6, the temperature of the spent fuel pool: 123.8 degrees Fahrenheit.
o As of 2:30PM on April 6, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 3 reactor
o At 7:30AM on April 6, the temperature directly above the spent fuel pool by thermography measurement: 140 degrees Fahrenheit.
o At 7:30AM on April 6, the temperature directly above the primary containment vessel by thermography measurement: 89.6 degrees Fahrenheit.
o At 12:00PM on April 6, pressure inside the reactor core: 0.005MPa.
o At 2:00PM on April 6, water level inside the reactor core: 1.8 meters below the top of the fuel rods.
o At 12:00PM on April 6, pressure inside the primary containment vessel: 0.1069MPaabs.
o At 12:00PM on April 6, the temperature of the reactor vessel measured at the water supply nozzle: 173.8 degrees Fahrenheit. (This figure is under investigation.)
o As of 2:30PM on April 6, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 4 reactor
o At 7:30AM on April 6, the temperature directly above the spent fuel pool by thermography measurement: 134.6 degrees Fahrenheit.
• Fukushima Daiichi Unit 5 reactor
o At 1:00PM on April 6, the temperature of the spent fuel pool: 95.4 degrees Fahrenheit.
• Fukushima Daiichi Unit 6 reactor
o At 1:00PM on April 6, the temperature of the spent fuel pool: 85.1 degrees Fahrenheit.
• Fukushima Daiichi Common Spent Fuel Pool
o At 8:00AM on April 6, the temperature of the spent fuel pool: 80.6 degrees Fahrenheit.
• Others
o At 3:00PM on April 5, TEPCO began to install the components of a silt barrier near the south sea wall of Fukushima Daiichi Nuclear Power Station in order to contain the spread of discharged radioactive water.

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)

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TEPCO Washington updates

Here are updates on Fukushima Daiichi NPS.
(1) Injection of nitrogen to reactor containment vessel of Unit 1
(2) Detection of radioactive material in the soil in Fukushima Daiichi NPS: Detected Pu-238 might come from reactors.
(3) Outflow of fluid containing radioactive materials to the ocean from areas near intake channel of Unit 2 was shut off.

Contacts:
TEPCO Washington Office 202-457-0790
Kenji Matsuo, Director and General Manager
Yuichi Nagano, Deputy General Manager,
Masayuki Yamamoto, Manager, Nuclear Power Programs

(1) Injection of nitrogen to reactor containment vessel of Unit 1

Taking into account the possibility of hydrogen accumulating inside, we have been considering encapsulation of hydrogen by injecting nitrogen to the reactor containment vessel.

On April 6, we received an order from minister of economy, trade and industry to report on matter such as necessity of encapsulating nitrogen, method for implementation, and impact assessment of safety. Accordingly, we have compiled related matters and reported to Minister of Economy, Trade and Industry. The report was approved after the deliberation in the Ministry of Economy, Trade and Industry.

Base on the report, we began injecting nitrogen to the reactor containment vessel of Unit 1 around 10:30pm.

[Comments]
・ In the Unit1, 2, and 3 of Fukushima Daiichi NPS, it is estimated that water injection to remove decay heat in RPV is generating steam inside of primary containment vessels (PCV). Because it is assumed that the inside of PCV is mostly steam, we evaluated hydrogen accumulation is not high, hence possibility of hydrogen explosion is limited.
・ However, there is a possibility that the RPV boundaries of all three units have been damaged. If we continue cooling reactors through injection of water, there is a concern regarding possible explosion caused by concentration of hydrogen which might leake from RPV to PCV. In order to prevent possible combustion of hydrogen for these units, we determined to inject nitrogen to each PCV.

Volume of steam inside of the PCV will decrease through condensation at wall of PCV (Heat-transfer to the outside of the PCV) and injected water to the reactor which was not consumed for the decay heat removal. In addition, an impact of condensation from heat transfer at wall is no greater than that of the injected water. On the other hand, it is necessary to continue injecting water to the reactor to cool the core, and the amount of water injection will be more than needed for the decay heat removal.

・ As for unit1, the damage to D/W is supposed to be relatively light compared to unit 2. Therefore, in the case of increase in concentration of steam, pressure in PCV would become negative along with increase of hydrogen through cooling of the reactor. Moreover, oxygen might be supplied to PCV by in-leak and partial-pressure of hydrogen would increase, which would make the atmosphere susceptible to reach combustible limit. In order to prevent this, we determine injection of nitrogen to unit 1 first, then to unit 2 and 3.

(2) Detection of radioactive material in the soil in Fukushima Daiichi NPS (continued report)

As part of monitoring activity of the surrounding environment, we conducted analysis of plutonium contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station. As a result, plutonium 238, 239 and 240 were detected. (we reported this on March 28) Subsequently, from the 3 spots where periodic sampling was conducted on March 25th and 28th and from another spot which was supplemented on 25th, we conducted analysis of plutonium contained in the soil. As a result, plutonium 238, 239 and 240 were detected. See Table (1) and Figure (2) for detail.

In addition, we conducted nuclide analysis of gamma ray contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi NPS. Such analysis was also conducted on soil collected on March 25th and 28th at the 4 spots. As a result, radioactive materials were detected as described in the attached excel file. Accordingly, we have reported the result of analysis to Nuclear and Industrial Safety Agency and Fukushima Prefecture.

[Comment]
Density of detected Pu-238, Pu-239 and Pu-240 are within the same level of the fallout observed in Japan after the atmospheric nuclear test in the past. Activity ratio of Pu-238 detected in site field on March 25th and 28th and also detected in adjacent to industrial waste disposal facility against Pu-239 and Pu-240 are 1.6, 2.2 and 2.0 respectively. They exceed activity ratio of 0.026 which resulted from the atmospheric nuclear test in the past, thus those Pus are considered to come from the recent incident.

Pu-238, Pu-239 and Pu-240 are also detected from samples collected from site field on March 21st. Pu-238 was (5.4±0.62)×10-1Bq/kg, Pu-239/240 was (2.7±0.42)×10-1Bq/kg)

(3) Outflow of fluid containing radioactive materials to the ocean from areas near intake channel of Unit 2 was shut off.

At around 9:30 am on April 2nd, we detected water containing radiation dose over 1,000 mSv/h in the pit where supply cables are stored near the intake channel of Unit 2. Furthermore, there was a crack about 20 cm on the concrete lateral of the pit, from where the water in the pit was outflowing.
We have implemented sampling of the water in the pit, together with the seawater in front of the bar screen near the pit. These samples were sent to Fukushima Daini Nuclear Power Station for analysis.

We also injected fresh concrete to the pit on April 2 to stop the outflow, but we could not observe a reduction in the amount of water spilling from the pit to the sea. Therefore, we started to inject the polymer on April 3rd.

From 7:08 am to 7:11 am on April 4, we put the tracer into the pit and began an investigation of water flows. Additional tracer was put through the two new holes drilled near the pit. At 2:15 pm, April 5, it was observed that the tracer came out from the crack on the concrete lateral of the pit. At 3:07 pm, injection of coagulant from the holes was initiated.

At 5:38 am on April 6, we observed the water spilling from the crack on the concrete lateral of the pit stopped.

Shutoff of water outflow was confirmed at approx. 5:38 am on April 6th, 2011.

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Update to Information Sheet Regarding the Tohoku Earthquake

The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office

As of 3:00PM (EST), April 7, 2011
• Radiation Levels
o The concentration of radioactive nuclides from the seawater sampled at the screen device (installed to remove waste before the intake of seawater) of Unit 2 and sampled near the seawater discharge point (south side) of Fukushima Daiichi Nuclear Station were as follows:

Nuclides
(half-life) Concentration (Unit : Bq/cm3) Ratio
Sampled at the screen of Unit 2 at 7:40AM on April 6 (a) Sampled at south side discharge point at 2:05PM on April 6 (b) Maximum Permissible Water Concentration (c) a / c b / c
I-131
(8 days) 5.6 x 103 3.7 x 100 4.0 x 10-2 140,000 93
Cs-134
(2 years) 3.1 x 103 2.4 x 100 6.0 x 10-2 52,000 40
Cs-137
(30 years) 3.2 x 103 2.5 x 100 9.0 x 10-2 36,000 28

o At 6:00PM (JST) on April 7, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 99 micro Sv/hour.
o At 6:00PM on April 7, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 56.8 micro Sv/hour.
o Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on April 7 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm
o 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.

• Plant Parameters
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
pressure inside the reactor core (gauge pressure, MPa) 0.375 -0.009 0.000 – 0.002 0.008
4/7
12:00PM 4/7
12:00PM 4/7
12:00PM – 4/7
12:00PM 4/7
12:00PM
pressure inside the primary containment vessel (absolute pressure, MPaabs) 0.165 0.100 0.1059 – – –
4/7
12:00PM 4/7
12:00PM 4/7
12:00PM – – –
water level inside the reactor core (meter) *1 -1.65 -1.5 -1.9 – +1.801 +1.816
4/7
12:00PM 4/7
12:00PM 4/7
12:00PM – 4/7
12:00PM 4/7
12:00PM
temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) 434.8 290.5 190.9
*2 – – –
4/7
12:00PM 4/7
12:00PM 4/7
12:00PM – – –
temperature of the spent fuel pool (degrees Fahrenheit) – 123.8 – – 96.8 69.8
– 4/7
12:00PM – – 4/7
12:00PM 4/7
12:00PM
the temperature directly above the spent fuel pool by thermography measurement (degrees Fahrenheit) 75.2 – 140.0 134.6 – –
4/6
7:30AM – 4/6
7:30AM 4/6
7:30AM – –
temperature directly above the primary containment vessel (degrees Fahrenheit) 84.2 – 89.6 – – –
4/6
7:30 – 4/6
7:30 – – –
temperature directly above the second containment building (degrees Fahrenheit) – 89.6 – – – –
– 4/6
7:30 – – – –
Amount of water in total shot/injected to the spent fuel storage pool (tons) 90 299 – 314 5,048 1,493 – –
as of 4/7
7:00PM as of 4/7
7:00PM as of 4/7
7:00PM as of 4/7
7:00PM – –
*1: Minus figure means that water level is below the top of the fuel rods.
*2: This figure is under investigation.

• Fukushima Daiichi Unit 1 reactor
o At 1:31AM on April 7, TEPCO began the injection of nitrogen gas into the primary containment vessel to prevent an explosion by accumulated hydrogen gas.
o As of 3:30PM on April 7, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 2 reactor
o At 1:29PM on April 7, TEPCO began to inject freshwater into the spent fuel pool, until 2:34PM (approximately 36 tons in total).
o As of 3:30PM on April 7, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 3 reactor
o At 6:53AM on April 7, TEPCO began to shoot water aimed at the spent fuel pool, until 8:53AM, with a specialized vehicle normally used for pumping concrete (approximately 70 tons in total).
o As of 3:30PM on April 7, the injection of freshwater into the reactor core continues.
• Fukushima Daiichi Unit 4 reactor
o At 6:23PM on April 7, injection of freshwater into the spent fuel pool commenced.
• Fukushima Daiichi Common Spent Fuel Pool
o At 7:45AM on April 7, the temperature of the spent fuel pool: 82.4 degrees Fahrenheit.
• Others

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)

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TEPCO Washington Office 202-457-0790
Kenji Matsuo, Director and General Manager
Yuichi Nagano, Deputy General Manager,
Masayuki Yamamoto, Manager, Nuclear Power Programs

(1) Aftershock at 23:32, April 7: No damages at Fukushima Daiichi/Daini NPS

At 23:32, April 7, there was a large aftershock near Fukushima Daiichi and Daini NPS.

So far, no damages and injuries are reported at both sites.

TEPCO will investigate the sites tomorrow morning then determine whether it would be necessary to change scheduled work.

The figures indicated at monitoring posts at the station boundary are within the usual range, and there is no influence of radioactivity outside as of now for both Fukushima Daiichi and Daini NPS.

Also there is no changes in radioactivity monitoring at the stacks in Fukushima Daini NPS.

Maximum observed acceleration of the earthquake base was 58.1 Gal at reactor building of Fukushima Daini unit 3 (No data available from Fukushima Daiichi NPS).

(2) Impact of radioactive water release to the sea

The following is information regarding impact of radioactive water discharge to the sea.

2-1: Impact of the discharge of the low level radioactive wastewater implemented on April 4th.
–> The radioactive density measured around the south water discharge has been decreased slightly, and so we could say we will not find an impact of the water discharge.

On the other hand, the radioactivity density measured around the north water discharge is a little bit bigger than yesterday’s. The discharge from the sub-drainage might have caused this to some degree but these 2 changes in the measured density are within the variation range already measured in the past, and we could think that there is no impact of the water discharge on the radioactivity density in the seawater. We will continue monitoring any changes in samples.

–> After the water discharge, we have been taking samples at 3 more points 15km offshore, and we now do so twice in a day, but in any event the results are almost the same level as the other ones at the points 15km offshore.

2-3: Impact of the water discharge to the environment and human bodies.

–> As to this sampling, we are still at the stage for monitoring the tendency or the variation and collecting and analyzing data, therefore we think that we are not ready for conclusion. However we have been doing our best and trying to clarify and release them as soon as possible.

The impact of the exposure to radiation might emerge by taking in radioactive materials but, since seawater is not for drinking and considering how the seafood is consumed, we would think that no immediate impact will be caused.

2-4: Reportedly, Cesium of 510 Bq, which is bigger than the temporary regulation value for the fish (500 Bq/kg) has been detected in Ammodytes personatus landed in the Ibaraki offshore.

–> We are very sorry that we have cause so many concerns and so much inconvenience to the people who live near the sites, people in Fukushima Prefecture and other people concerned.

We think that it is possibly due to the accident in Fukushima Daiichi Nuclear Power Station and we need to take sampling in the wider range to verify the influence of radioactive materials discharged. We have added 3 more sampling points to the present 3 points 15km offshore and we are taking samples twice a day. We will continue monitoring the trends and changes.

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> Cesium of 510 Bq … We think that it is possibly
> due to the accident in Fukushima Daiichi ….

Vague PR/lawyer wording? Or a hint some other source out there may be showing up that’s been around undetected, until the intensive sampling lately?

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Hank Roberts, Cesium-137, Strontium-90 and various plutonium isotopes are present all over the world due to nuclear weapons testing. You can google images them, here are some examples.

http://maps.grida.no/go/graphic/cesium_137_from_nuclear_weapon_testing_fallout_1995_figures

As we can see background deposition is quite high, at over 1000 becquerels per square meter.

http://3.bp.blogspot.com/-6cz-0zfc5J4/TXy-BtIuJlI/AAAAAAAAAKg/Q2ykaZakGkQ/s1600/Chernobyl%2Bmap%2BCaesium-137%2Bcontaminated%2Bareas%2Bin%2BEuropean%2Bcountries.bmp

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