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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”

Cyril R, on 2 April 2011 at 4:34 AM said:

I’m not sure what you guys are talking about, but dose levels everywhere around Fukushima have been on a declining trend for over a week now:

Click to access ENGNEWS01_1301652988P.pdf

Obviously the nuclides came with the steam relief as the cores were already damaged then, and then it stopped because decay heat dropped further and seawater cooling continued. The data explains this perfectly.

—————–

Cyril.

that may be true as of late (lets hope it is)

But the total radiation released in the first days and weeks now appears to be much higher than previously indicated by those who quoted various readings out of context with location and wind direction.

Read…

Preliminary Assessment of Accident Sequences and Potential Atmospheric Radiation Releases

Click to access Accident_Sequence_Fukushima_31March2011.pdf

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Contrasting perspectives from Dr. John Price (former member of the Safety Policy Unit at the UK’s National Nuclear Corporation) and Laurence Williams (Professor of Nuclear Safety at England’s University of Central Lancashire and the former head nuclear regulator for the UK). And the Wall Street Journal thrown in for good measure.

From ABC News: “Crews ‘facing 100-year battle’ at Fukushima” (April 01, 2010).

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Hank: I don’t think I misinterpreted anything. We’re talking about two different things.

What I was referring to was a widely circulated UCS press release, concerning march 30 IAEA.

here it is:

The IAEA is reporting that measured soil concentrations of Cs-137 as far away as Iitate Village, 40 kilometers northwest of Fukushima-Dai-Ichi, correspond to deposition levels of up to 3.7 megabecquerels per square meter (MBq/sq. m). This is far higher than previous IAEA reports of values of Cs-137 deposition, and comparable to the total beta-gamma measurements reported previously by IAEA and mentioned on this blog.

This should be compared with the deposition level that triggered compulsory relocation in the aftermath of the Chernobyl accident: the level set in 1990 by the Soviet Union was 1.48 MBq/sq. m.

I think what may have happened is that in making the internet rounds, it was attributed to Lyman.

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Cyril: I read your graph earlier.

Given the unevenness of distribution, the high cesium levels in that one location might be compatible with the graph. ?? what do you think?

I was objecting to the press release’s misleading paraphrase of the IAEA report. I don’t see how anyone can justify the press release’s version of the report.

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“sod: there are defenders of nuclear power who don’t think labor exploitation exists and then there are defenders of nuclear power who are marxists. and many positions in between. ”

i am not talking about social aspects of workers without the necessary equipment. i am talking about security aspects of having the wrong equipment.

without running water, they can not decontaminate. they should not work under those conditions.

without enough dosimeters, we simply do not know how high doses they accumulated. one dosimeter per group tells us nothing about individuals.

———————–

[deleted personal opinion presented as fact. Please re-post with links/refs.]

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> Cyril R., on 1 April 2011 at 4:51 AM said:
> The shroud cannot fail in a way which would
> compromise cooling during emergencies

A citation to the source for your belief would help, if you have a basis for believing this. If you have a source for believing it, why do you trust your source?

Looking it up, I can’t support what you claim.

I find much discussion, e.g.:

http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=561142

“… Although assessments by the USNRC staff of the potential significance of this cracking have shown that core shroud cracking does not pose a high degree of risk in the short term, the staff concluded that the cracking was a safety concern for the long term because of the uncertainties associated with the behavior of core shrouds with complete 360{degrees} through-wall cracks under accident conditions and because it could eliminate a layer of defense-in-depth….”

and
http://www.inl.gov/technicalpublications/Documents/3314495.pdf.
“… instances of core shroud cracking served to escalate attention as to the seriousness of the IGSCC problem in BWR reactor internals…. The primary emphasis has been placed on core shroud degradation, but common mode or cascading failure of other components could also have safety significance….
“… consideration is given to potential cascading and common mode effects on system performance stemming from cracking of core shrouds and other BWR reactor internals components when subjected to design-basis and beyond-design-basis accident loading conditions such as seismic events….. It is recognized that other degradation mechanisms such as fatigue can act synergistically with IGSCC in that a crack which is initiated by IGSCC can propagate to failure from fatigue….

But looking forward over time, looking up citing references, I can’t find the conclusion you state above that this is now known to be no problem. What’s your source for that?

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Rational Debate wrote:

Listening to NHK live TV, they’ve got video of the tsunami up against a cliff in one area (I didn’t catch where, I’m sorry!) such that it could be analysed. They’re saying it’s confirmed to have been over 20 meters high (65.6 ft).

Question for you RD. In light of this information, are you suggesting we should reconsider site design criteria for power plants located in coastal areas? Japan probably has dozens, and we (if you are in the US) have a few of our own. Should we be shutting down plants until they are retrofitted with sufficient defense in depth criteria to withstand probabilistic assessments at those specific sites? In 1929, The Grand Banks earthquake resulted in a 7 meter tsunami that swept the coast of Newfoundland (it was actually three successive waves that reached land 2.5 hours after the initial earthquake). What is the rational response to this information from someone who also appears to be a strong proponent of the industry?

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re post by: Cyril R, on 2 April 2011 at 4:34 AM said:

I’m not sure what you guys are talking about, but dose levels everywhere around Fukushima have been on a declining trend for over a week now:….

Hi Cyril,

The link you provided is great, thanks! What they’re talking about is a different aspect of the big picture. The link you found is measuring the dose rate from pretty much everything – cloud ‘shine’ and direct exposure to the plume, ground ‘shine’ (dose rate from radiation deposited on the ground), and so on.

In effect it’s from a piece of monitoring equipment that is measuring the ambient dose rate. Some degree of this dose rate may be coming from stuff that is passing you by, blown on the wind. That degree can be a lot, or a little, all depending on circumstances.

A part of it, however, will be coming from ground shine. So you can measure just what isotopes have actually been deposited on the ground. Of course they’ll primarily report and look for the most concerning isotopes – ones that can get in the food chain, or that produce the most shine, etc. Depending on the surface, ground deposition is what is to some extent going to be there over time. Some of it may wind up picked up in the wind again and blown away, but much of it will stay – the surface type itself helps determine just how ‘fixed’ that contamination is or isn’t, in combination with wind, rain, etc.

Anyhow, that’s what they’re talking about. Typically with the more likely accident scenarios, the dose rate being released from the plant will spike, and then taper off – the faster the better of course. There may be multiple spikes if there is periodic venting occurring – you see this most clearly right near the plant and various factors muddle it up a bit the further away you go.

Usually under most hypothetical scenarios the initial spike will be the worst, and then it will taper off. All sorts of things can affect that for a particular location however, as I’m sure you’re already aware – changes in wind direction or precipitation especially. Even topography can have major effects, either concentrating or reducing the dose rate. These factors are expected, including the likelihood of some ‘hot spots.’

Hot spots in this context doesn’t refer to the magnitude of either dose rate or deposition, so much as small relatively localized areas that because of a combination of the factors I’ve mentioned wind up with a notably higher dose rate or deposition amount than surrounding areas. We’re seeing what may be a prime example of this right now with the one small city to the NW of the plant that is outside of the exclusion zone.

Anyhow, even as the dose rate tapers off as in the graphs you linked to, the total deposition is likely to continue increasing to some extent. It will do so as long as there is some plume passing by. The RATE of deposition will almost certainly be dropping, because it is a function of how much is in the plume and how much of that plume is passing thru – so the total amount on the ground would still be increasing even if at a slower and slower rate until there isn’t any plume passing by.

Once it’s there all sorts of things then proceed to move it around… the already mentioned wind & precipitation, but also run off from any water, bioaccumulation, and so on. Even if contamination levels wind up high, there are often a number of things that can be done to decontaminate the area and make it safe again. You always hope that doesn’t wind up being necessary – as you can imagine trying to decon large areas can be pretty labor and $$ intensive. If it’s a city, just wiping down surfaces or washing them off can make a huge difference. If it’s ground, you may wind up removing the top inch or so of soil, that sort of thing.

Anyhow, that’s the gist of it.

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rational debate:

thanks for your post. It helped me a lot. I saw the distinction in the IAEA report between total and daily deposition but it wasn’t salient for me because I am not sufficiently familiar with the vocabulary. and these adjectives were not always employed, thus making the numbers a bit confusing to me.

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re post by: sod, on 2 April 2011 at 6:13 AM said:

without running water, they can not decontaminate. they should not work under those conditions.

without enough dosimeters, we simply do not know how high doses they accumulated. one dosimeter per group tells us nothing about individuals.

Sod, why is it that you don’t bother noting that they’ve already corrected the situation and have dosimeters for everyone now?

On the water front (pun intended): They don’t have running water as in infrastructure supplied tap water, regular water to sinks and so on. They DO have water for decontamination. Just because the infrastructure that normally provides running water to the plant isn’t working doesn’t mean that they don’t have water on site, portable decon units, tanks with sprayers, etc. Just one example, you know they’ve got fire trucks there full of clean water. Plus, you don’t even necessarily need running water of any sort for decon – sometimes just a wipe is more than enough. I think you are making more of and reading more into the water issue than is the case. Not having regular running taps and so on is very inconvenient – but it doesn’t have any bearing on ability to decontaminate.

As to the dosimeter issue – I just saw that late last night/early this morning. It is very disconcerting. I would say ‘unexcusable’ except that wouldn’t necessarily be the case given the mass destruction in Japan. They apparently had over 5,000 dosimeters, and all but about 3xx were destroyed. IF they made prompt efforts to get all the dosimeters they could from other plants, including not only their own but any other ones, and from other sources, but weren’t able to get them for whatever reason (e.g., not a fault of theirs or lack of trying or something) then it wouldn’t be fair to slam them on this. Clearly they HAVE to try to keep these units from having worse problems. I have a hard time imagining that they wouldn’t be able to get more dosimeters however. But we don’t know any of the key pertinent details.

Next, as to your statement “one dosimeter per group tells us nothing about individuals” That quite simply is NOT true. It all depends on the area, the dose rate, sources present in the immediate area, and the training those sharing a dosimeter were given. A single dosimeter used in a small group that is working in an area that has a fairly consistent dose rate gives quite good information about the group dose.

Now don’t read into what I am saying. I am NOT saying that at Fukushima Dai-ichi this situation was ok. I am NOT saying that it’s ideal or anything like that. I am saying that if forced by circumstances, and done judiciously, you absolutely can get decent information about the dose each individual got.

If management/staff responsible at F.Dai-ichi didn’t do everything possible to get more dosimeters, it is utterly inexcusable. If other plants or vendors were unwilling to loan/sell dosimeters to TEPCO when/if asked, it is utterly inexcusable. That still doesn’t mean that they can’t know the individual dose from shared dosimeters, however, if they were careful about how they did this.

As usual, we don’t even begin to get enough data from these articles to know who should or shouldn’t be blamed. On the face of it, it sure doesn’t sound good tho.

Meanwhile, for you to say this; “is there anything that they can do to the workers that will cause an outcry among the supporters of nuclear energy? no water, no dosimeter. this is criminal stuff!” is just unwarranted and inflammatory on several fronts.

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re post by: Gregory Meyerson, on 2 April 2011 at 7:53 AM

You’re sure welcome Gregory! All of the exposure and contamination issues get really complicated – many many individual factors all of which are fairly straightforward and logical, but so many all interacting with each other that it becomes very complicated. Difficult to explain well in online posts – heck, entire books are written about it. :0) But trying to help folks who may not be familiar with some of these things with basic understanding of the big picture concepts where I can and as best I can with little time and unfortunately tossing things down in posts pretty quickly. Then any more detailed issues we can take to the technical open thread if they come up.

Thanks for the feedback too, it’s nice to know that some of my posts have been useful.

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re post by: EL, on 2 April 2011 at 7:23 AM said:

….are you suggesting we should reconsider site design criteria for power plants located in coastal areas? …we (…in the US) have a few of our own. Should we be shutting down plants until they are retrofitted with sufficient defense in depth criteria to withstand probabilistic assessments at those specific sites? In 1929, The Grand Banks earthquake… What is the rational response to this information from someone who also appears to be a strong proponent of the industry?

Hi El,

I’m a strong proponent of facts, good science (there’s plenty out there that’s not), and logical thinking, and revising if new BETTER (more factual, accurate, etc) data becomes available.

We really ought to take this one to the philosophical open thread. So I’ll post a response there in a little while, have some things I have to get done first. You may want to copy your post over there in the meantime.
MODERATOR
Well spotted RD. I would say philosophical too.:-)

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Interesting talks on Thursday at the University of Melbourne Department of Engineering, especially from Professor Iven Mareels – his estimates of the damage to the reactors is available online.
[video src="http://www.eng.unimelb.edu.au/nuclear/FukushimaFactsFallout.mp4" /]

Barry, you seem remarkably sanguine about the fuel assemblies, rejecting “in your personal judgement” the need to entomb them. Mareels is a lot more concerned, and I quote: “estimates of the likelihood of a meltdown and the size of it: number 1 around 70 per cent, number 2 around thirty per cent, number 3 probably completely” – download his talk and slides at
[video src="http://www.eng.unimelb.edu.au/nuclear/FukushimaFactsFallout.mp4" /]

[ad hom deleted]

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Trying to put in camera to trace leak:

‘Tokyo Electric Power Co. officials said they hope to place a camera in a maintenance tunnel to determine whether water is leaking from a joint of the trench, which could help to explain the troublesome spread of contaminated water around the plant.’

Resin Spraying:
‘Crews also sprayed 2,000 liters (more than 500 gallons) of synthetic resin meant to bind radioactive particles to the site and prevent them from spreading, according to Tokyo Electric.’

Concrete pumps to be used to pump water:
‘And huge concrete pumps described as the largest such machines in the world were being readied for delivery to the Fukushima plant as efforts continue to spray water onto the spent fuel pools and reactors at the plant to help keep the nuclear fuel cool. ‘

Beef not contaminated:
‘Japan’s health ministry said Friday that it appeared an earlier report indicating there had been radioactive contamination of beef may have been wrong.

The ministry said faulty testing may have led to the result, which indicated levels of radiation slightly in excess of those allowed by Japanese law. In a second round of tests, lab workers were unable to find any trace of radioactive cesium in the same cattle, according to the reports.
Even if the report was accurate, the amount of radiation detected — 510 becquerels per kilogram — would expose a consumer who ate 95 pounds of beef in a year to 0.35 millisieverts of radiation, according to Nolan Hertel, a Georgia Tech nuclear engineering professor.
Someone living in an industrialized nation is typically exposed to 3 millisieverts per year.
Authorities had previously banned the sale and transport of numerous vegetables grown in the area after tests detected radiation.’

Water in tunnels partly drained and no longer urgent:
‘Concerns also remained about other water that has shown high levels of radiation.
This includes water in exposed maintenance tunnels leading into and out of the Nos. 1, 2, 3 and 4 reactor buildings, one of which earlier had radiation levels 100,000 above the norm.
Authorities have been working in recent days to drain these tunnels, to prevent them from spilling over and sending tainted water into the ground. By Friday, an official with the Tokyo Electric Power Company — which operates the plant and heads the recovery effort — said water levels had dropped one or more meters, and that the issue was no longer urgent.’

Groundwater radiation levels unclear. Probably not just from the air.
‘Early Friday, a Tokyo Electric official said that iodine-131 levels in ground water from a pipe near the No. 1 reactor had 10,000 times the standard limit. But the utility later backtracked, promising to get more clarity later.

Edano addressed this confusion in a news conference later Friday, noting that a “constant amount of radiation” appeared to be getting into the groundwater while noting that further tests are forthcoming.

“The numbers released … looked strange, and that led to the recalculation,” he said. “In either case, underground water seems to contain some level of radioactive substances, and this leads to an understanding that the … soil in the vicinity needs to be monitored closely.”

All this contamination — both into the ground and, eventually, the sea — is the result of a leak or some other sort of ground seepage from one of the nuclear plant’s four most embattled reactors, a Tokyo Electric official said Thursday. The official noted that the high levels suggest the release of radiation into the atmosphere alone couldn’t be the lone source.’

http://edition.cnn.com/2011/WORLD/asiapcf/04/01/japan.nuclear.reactors/index.html?hpt=T2

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@Peter Burnett:

a couple of flaws I see on the surface of the UoMelbourse presentation:

1) 9.0 earthquake was NOT within design limits…

2) where do they get the information that the torus of unit 2 is damaged? seems to be at the crux of their argument that damage occurred on the bottom of the RPV..?

the presentation clearly appears to be for educational purposes, seems to make some assumptions and “glosses over” intricate details for one reason or another…

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re to Rational Debate, on 2 April 2011 at 8:01 AM

thanks for the answer.

i know that they have enough dosimeters now. i strongly disagree with your assessment of group dosimeters being useful in the environment that they face there. ( we had a least one incident, with contaminated waters, in which the group got very different doses)

one important point about the missing dosimeters are the claims about doses that workers received. we simply do not know it, when they didn t use dosimeters properly.

———————

on the lack of running water:

water was a scarce resource at the plant. we know that, because they didn t even have sufficient drinking water. (and multiple other small things)

http://articles.latimes.com/2011/mar/29/world/la-fg-japan-workers-20110329

i am a little surprised by the claim that running water isn t needed for decontamination. it is, even when things go fairly well, just to wash away accidential contamination during undressing. it is even more important in a potentially contaminated indoor area.(and of course i am speaking about water being delivered there, not about reconnection to official water pipes)

——————

these aspects are very important, because obviously the work of these people did stop the accident from getting even worse. and whether people in the future will volunteer for a similar job (and that for our safety) depends on whether we do our best for those working there today.

i simply can not understand, why you would send people there without full equipment (including a dosimeter, of course!!!)

why they would sleep on the floor. (why they would sleep inside the compound at all?!?)

why they don t work in shifts. why they don t have military NBC containers to support their work. …

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Barry Brook Wrote:

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).

This doesn’t look very stable to me.

From the data set provided here.

RP: Reactor pressure
D/W: Drywell pressure
S/C: Suppression chamber (wet-well) pressure
FNT: Feedwater nozzle temperature
BHT: Bottom head temperature

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@David Martin: all japanese sleep on the floor. may appear strange, but it’s their habit (and a very conformable one, both for the back and for the space).
and yes, hey work in shifts, otherwise it would be impossible to work no-stop for three weeks…

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@BerGonella
?? I do not post opinion here, simply try to update news.
I think that you are addressing the wrong person.

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MODERATOR
Please note that several comments, most of which were lodged overnight, are being held in the Pending/Moderation queue until Prof Brook returns some time today. Please be patient.

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@sod, on 2 April 2011 at 9:13 AM

“i simply can not understand, why you would send people there without full equipment (including a dosimeter, of course!!!)”

The same reason first response firemen sometimes have to run into a burning building to save lives, often without all the equipment and backup they would like.

The conditions are such that they are very arguably still in “first response” mode.

There is an underlying assumption that Tepco just doesn’t care because conditions aren’t ideal or maybe they are trying to save a few bucks by withholding food and water and sleeping mats, and saving gas on transport of off-duty workers to a safe shelter. There are no facts to prove that, just semi hysterical allegations based on snippets of information that may be unreliable and in any event is not taken in context of the utter devastation that surrounds that plant.

Much of what you are claiming is based on a Fox News story, allegedly based on an anonymous (and therefore unverifiable) mother of a plant worker, speaking through an interpreter. That’s great infotainment but I wouldn’t condemn the operation based on that article.

http://www.foxnews.com/world/2011/03/31/japans-nuclear-rescuers-inevitable-die-weeks/

Fox News also reported today – on the air – that “blue lights” were seen at one or more reactors, claiming it as evidence of re-criticality. I did some googling and found only one private blog mentioning “blue lights” at the plant and it was obvious to me the report was not credible. Someone probably saw blue illumination lights, assuming it wasn’t made up out of whole cloth.

Fox then put that clip on their web site. But I can’t link to it because for some strange reason I can’t find it now.

I have no doubt doubt Fox dredged that blue light report out of that private blog, simply because it isn’t discussed anywhere else.

At the very least I’d give that report on the workers condition a day or two to see if it “sticks”. [Ad hom deleted]
Mods: feel free to edit my media directed ad-homs as you see fit. I just don’t know any better way to put it and I’m a Republican, and in this case ought to be sympathetic to Fox but I call em as I see em.

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Fukushima vs. TMI fuel melting

There is a very informative (long) 4/1 update by KBMAN. Best to go straight over there to read as the discussion builds on premises that must be read in sequence.

One summary point — because of the differences in BWR vs PWR fuel design, KBMAN speculates that Fukushima fuel melting has been much slower than TMI. That implies quite different activity by any corium dropping to the bottom of the RPV:

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confused by the fussion, on 2 April 2011 at 11:27 AM — Somebody made a mistake, as reported.

The general situation in Japan has not been ordinary since 2011 Mar 11.

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@EL, on 2 April 2011 at 10:24 AM

Thanks heaps for that dataset link for units 1, 2, 3. Just what I have been looking for.

This doesn’t look very stable to me.

What are you seeing that you don’t like?

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In the comments KBMAN explained clearly both the concentration of the source of contaminated water, and the encouraging fact that TEPCO can drain the basements while keeping up with the core cooling:

Oh absolutely, there is some source of highly contaminated water. And considering that it was still that high despite dilution by the tsunami water means that the source is far more concentrated. This is the kind of symptom that causes me to suspect that significant amounts of fuel went into solution rather than melting.

Another consideration regarding the incident at unit 3 is that the source water likely drained from the reactor building or turbine building into the basement where it met the backed up drain water from the trench. Given that the area was relatively dry the day before, the water they stepped in may not have had much dilution to that point in time. OTOH the 1 Sv/hr reading on the trench water at unit 2 is presumably after dilution.

The whole point of the relative contributions was not to minimize the impact or importance of the leaks. But rather, it was to point out that the current rate of leakage does not prevent them from being able to get the basements drained while also maintaining cooling of the reactors. Sorry if this wasn’t more clear.

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I have been “off-line” for a couple of days and on returning find this TMI thread. No, not “Three Mile Island” but “Too Much Information”.

Before I had a chance to skim this thread I saw the Fox News report with the “Blue Light” and also a ridiculous suggestion that there is a shortage of radiation monitors. I have tried protesting such rubbish from Fox News before only to be totally ignored.

Blue light is what you find in pools of water contaminated with Beta emitters. This is called Cerenkov radiation.

For blue light to be seen external to the building there would have to be criticality in a place where ionizing radiation could emerge with minimal shielding material to obstruct it. This requires several rather unlikely events:

!. A prompt critical situation after control rods have been inserted.

2. The breach of the pressure vessel.

3. The breach of the main containment structure.

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After 2:40pm this afternoon, all comments have been in bold, rather than unbold. Any reason for this?

I find it slightly less easy to read.
MODERATOR
I don’t know what is going on with this. Barry is not on the blog right now but I will ask him about it and see if we can correct it.

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@John Bennetts,

Our much-overworked moderators have an unterminated paragraph tag in this comment “sod, on 2 April 2011 at 2:40 AM”

That’s the result of the moderator extra efforts to remove the totally-unacceptable without completely deleting the comment.
MODERATOR
Thanks for that Steve. I had a sneaking suspicion it may have been my error. However, in the Comments Page that I’m working with everything looks normal.You did mention it before and I went back to look at the comment by “sod” but didn’t get what was wrong. I will see if I can fix it myself now.

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MODERATOR – IMPORTANT MESSAGE
In future, comments will be deleted, if links are given, with accompanying quotes from articles etc., simply re-gurgitated, without critical feedback pertinent to the point being made by the commenter.Please be clear about your purpose for providing the link.

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TEPCO update 02.04.2011 10AM
(only new information pasted here)
Unit 2:
At 5:05 pm on April 1st, the
water injection was finished.

********

*From 3:00 pm, April 1st, we started spraying inhibitor in order to
prevent diffusion of radioactive materials. This attempt was conducted on
a trial basis at the mountain side area of the common spent fuel pool in
the range of 200m2. The spraying finished at 4:05 pm.

*Monitoring posts (no.1 to no.8) which were installed around the site
boundary have been restored. We will continue monitoring the measured
value and make announcements on those values accordingly.

http://www.tepco.co.jp/en/press/corp-com/release/11040201-e.html

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re post by: Barry Brook, on 2 April 2011 at 5:52 PM said:

MODERATOR – IMPORTANT MESSAGE
In future, comments will be deleted, if links are given, with accompanying quotes from articles etc., simply re-gurgitated, without critical feedback pertinent to the point being made by the commenter.Please be clear about your purpose for providing the link.

Does this apply to simple plant status updates also? I thought that was in large part what this thread was for? I’m sorry, I’m a little confused on what prompted this note or just what it applies to?
MODERATOR
This is a new directive from Barry which, as I understand it, is meant to prevent folk giving a link, with just a selective, often cherry-picked quote from the article/blog, without commenting on that quote and their purpose for quoting it. I will no doubt have to check with him from time to time if lines seem blurred. It does not apply to plant up-dates.

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Oh shoot! Moderator, I’m sorry, apparently I missed my closing /blockquote at the end of quoting your message… I hope it doesn’t wind up propagating thru the thread like the missed /b did…
MODERATOR
Seems OK :-)

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(@David Martin: sorry for my mistake, I actually addressed the wrong person about the people sleeping on the floor. it was intended to “sod” but I got wrong. I apologize)

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Moderator:
I had understood that the purpose of this thread was to provide updated information on the situation at the reactors rather than conducting extensive debate or argument and therefore have provided links to updates which did not seem to have appeared.
This understanding seems to be incorrect as you are asking for argument, but with, I believe, supporting links.
I would be grateful if you would clarify what you are looking for, and will of course be happy to comply with whatever your requirements are.
MODERATOR
I have asked Barry to give some more clarification. I don’t know whether he will be on the blog tonight, so this may not be answered straight away.

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Moderator:
Perhaps I should clarify that the reason I had edited quotes from news-sources I linked was so as to avoid issues mentioned which were not directly relevant to the plant and their condition, and so as to provide topic summaries rather than for the purpose of in any way ‘cherry-picking’ data, save as that is inevitable from any effort to keep it relevant and within what I had understood was the purpose of these threads.

I am therefore at a loss, and pending clarification of what is wanted will refrain from posting.
MODERATOR
See answer above.

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mpathmahoney;

The commited dose factor for Cs-137 is 14 nSv/Bq ingested( 5.0E-02 rem/μCi, src: http://www.bnl.gov/bnlweb/PDF/00SER/c-app.pdf ).

This estimate takes into account the absorption rate of Cs-137 by the GI tract and its biological half-life of 70 days(behaves much like sodium and potassium)

E.g. if you eat 2.9 kg of sushi per year, and sushi has an activity of 500 bq/kg(the legal limit for sale of sea food in Japan), you will over time absorb a dose of 20 microsieverts.

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MODERATOR
Would everybody please settle down and be patient. I have said the Barry is not available at the moment to clarify the new commenting rule. This is not a conspiracy to shut down comment but an attempt to keep the blog relevant and interesting/instructive. Sod and David Martin – I have put your last comments, regarding the new rule, in “Pending” as I can’t give you an answer and Barry will look at them immediately he logs on. In the meantime I suggest anyone who is unsure should hold off commenting, or post on the Open Threads which are specifically for opinions, ideas etc and where the commenting rules are more relaxed (except for ad homs, incivility and the like.)

TECHNICAL OPEN THREAD
Please restrict all discussion here to technical information, analysis, criticisms and questions on FD — no philosophising or excursions into whether nuclear power is ‘good’ or ‘bad’ or the implications of FD for the future of nuclear power (except for new technical developments, e.g. safety standards), etc. You may impart your deep wisdom on how the world should work on the Philosophical Open Thread.

PHILOSOPHICAL OPEN THREAD
Please keep all dialogue here to general and philosophical discussions on nuclear power, its benefits and limitations, its alternatives, history, media treatment of the FD accident, your views on how the world should work and why people should listen to you, etc., etc. Nothing technical please — leave that for the Technical Open Thread.

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David Martin, I think I understand what Barry is trying to do with this moderation rule, and I don’t think it was directed at your comments.

Over many discussions here prior to the Fukushima incident, we sometimes get commenters, typically motivated idealogues, who support their various contentions with hyperlinks that, when followed and read with comprehension, simply do not bear on the point they are trying to make. The inference is that they themselves have not read or understood their references, or are blindly throwing in entries from some fact file they keep, or forwarding talking points from activist groups, etc.

For an examples of this behaviour, see the many contributions from commenter “Machiavelli” in the Radiation thread, or search BNC for comments from “Webs and Weavers”, to name just two. We’ve seen this kind of behaviour here from the radiation alarmists, climate change denialists, proponents of various renewable energy technologies, and antinuclear activists.

This behaviour is offensive because it is a simulacrum of engaged critical thinking. It apes the process of critical thinking by giving the appearance of providing substantiation, when it does nothing of the sort. It degrades the intellectual integrity of the discussion.

So I can see why Barry is setting this moderation standard. I don’t know if I fully agree with it, because these commenters really do their case more harm than good. But there is no place for that kind of intellectual laziness in this forum.
MODERATOR
Thank you John for your input. I think you are probably “spot-on”.

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BARRY BROOK The commenting rules are not meant to be confusing, they’re meant to be logical. This is not a forum for cut-and-pasting slabs of text, with no other comment other than a link. Tell people why you think they should be interested in reading this, and what it means for this discussion. Otherwise, you’re not thinking and not contributing. Simple as that.

I’ll add a new clause to the commenting rules:

Citing literature and other sources: appropriate and interesting citations and links within comments are welcomed, but please DO NOT cite material that you have not yourself read, digested and understood. As a general rule, please introduce any and every link or reference with a short description of the material, your judgement on its quality, and the specific reason you are including it (i.e. how it is relevant to the discussion).

Remember, we are moderating, but are not in the business of censoring criticism — we welcome well-presented critiques. The principal concern is working out how to conduct this debate in a civil and evidence-based manner, and do it well. We may reject some comments at our discretion, but will never misrepresent your comment. Comments that break “the rules” a little will generally be posted anyway, but probably with a note appended by the moderator and/or the offending part obviously expurgated. Those who have regularly broken the rules are on permanent moderation — most manage to live with this. Those who started their BNC commenting career by insulting me or others here, including threats, swearing etc. were instantly put on the ban list. They can find any number of swamps on the internet in which to lurk — I’m not interested in having them here.

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I’m not speaking for either side of the nuclear debate here, but I just wanted to point out something about the posting rules, which I see two posts from the bottom at this moment.

If the “TECHNICAL OPEN THREAD” is limited to technical FD-only posts, and “PHILOSOPHICAL OPEN THREAD” is limited to any-subject, but non-technical posts, then there is no place here for technical non-FD posts, where technical rebuttal may be given on statements made about the general use of nuclear on the world stage. I have no rebuttal of my own to share in any of the threads, but I wanted to point this out, as it may have been an accidental statement.
It occurs to me that the policy could be specifically tuned to achieve such an exclusion. If so, I understand that this is your site, and as such you are free to handle matters as you see fit. If however you seek to allow for technical rebuttal to the whole of the nuclear industry, for objectivity’s sake, perhaps some segregated allowance can be made for non-FD technical discussion.

Your site is awesome, and I’ve learned a lot from it over the last few weeks. I appreciate your honesty, rigorous thought and info-mining.

Take care,
Joshua

MODERATOR
Joshua – I think you will find that, once the Fukushima crisis is less urgent, two simple Technical and Philosophical Open Thread will be established. In the meantime you should post non FD technical/philosophical points on the current OT’s.

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Question; Is reactor 3 the 800 pound gorilla? I’m reading JAIF and expert reports, namely on the RPV status, radioactive water, and the estimated fuel melt of reactor cores in 1 (70%) and 2 (30%), but there is less reporting on the status of reactor 3. We don’t have the same degree of updates on the core, RPV, or SPF of reactor 3. Mainly we have vague terms like damaged, or stable, Does this concern any of the experts here? Yes or no, please explain why?

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Steve Darden wrote:

Thanks heaps for that dataset link for units 1, 2, 3. for.

What are you seeing that you don’t like

For Reactor #1, RP and D/W pressures seem to follow each other (as expected) until they no longer follow each other. RP rapidly goes down, and D/W pressure rapidly goes up. This indicates to me steam is not being managed through torus or condensate and feedwater lines very effectively, and there is likely a significant pipeline break in ECCS inside primary containment. What this means for on-going cooling and containment efforts remains to be seen. Further support for this is suggested here (around minute 9:30).

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Details on how much is known (and how little is being told to the public) from an article about using forensics.

“… Governments and companies now possess dozens of these independently developed computer programs, known in industry jargon as “safety codes.” Many of these institutions — including ones in Japan — are relying on forensic modeling to analyze the disaster at Fukushima Daiichi to plan for a range of activities, from evacuations to forecasting the likely outcome.

“The codes got better and better” after the accident at Three Mile Island revealed the poor state of reactor assessment, said Michael W. Golay, a professor of nuclear science and engineering at the Massachusetts Institute of Technology.

These portraits of the Japanese disaster tend to be proprietary and confidential, and in some cases secret. One reason the assessments are enormously sensitive for industry and government is the relative lack of precedent: The atomic age has seen the construction of nearly 600 civilian power plants, but according to the World Nuclear Association, only three have undergone serious accidents in which their fuel cores melted down.

Now, as a result of the crisis in Japan, the atomic simulations suggest that the number of serious accidents has suddenly doubled, with three of the reactors at the Fukushima Daiichi complex in some stage of meltdown. Even so, the public authorities have sought to avoid grim technical details that might trigger alarm or even panic. ….”

—-
A few specifics given hint that far more could be told if the news folks go after it.

Shorter: why bother blogging, we’re not going to have facts, we’re getting “reassurance” — blogging can only speculate without pretending we will know enough to say anything useful. Pretty dismal as a news story.

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@EL, on 3 April 2011 at 4:55 AM

What this means for on-going cooling and containment efforts remains to be seen.

Thanks, I see. Reminds me of patient peering at ECG, think are those good wiggles or bad wiggles? It’s not clear to the amateur which are the significant patterns.

What is the source of the Unit 1 graph that you published with the raw data? Your own Excel I presume.

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“Hank Roberts, on 3 April 2011 at 7:17 AM said:
Details on how much is known (and how little is being told to the public) from an article about using forensics….modeling”

I would argue that the output of those models are not “known facts”, they are simply the speculations of the modelers, who fortunately have rarely had a chance to test their models.

I can only imagine the hysteria that would be generated by the media, turning model *predictions* into certain facts and certain fates, and cherry picking model predictions.

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NR99: you can see for yourself what the “modelers” have said. It’s more an explanation of what they think the accident progression was in R1 to R4, instead of a prediction of hysterical situations.

See Leo above at 7:46 AM

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What is the source of the Unit 1 graph that you published with the raw data? Your own Excel I presume.
It’s not my own. It’s from the following thread (and the link to the data too … which is very useful). Is it worth asking why there is so little data for the first 8 hours of the accident (prior to venting). Definitely looks like a pretty hectic period in the control rooms for three different reactors.

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Sadly, the first two casualties have been announced.

TOKYO — The operator of the stricken Fukushima Daiichi Nuclear Power Station said Sunday that two workers at the plant who had been missing for several days had been confirmed dead.

The operator, Tokyo Electric Power Company, said the workers were found in the basement of the turbine building connected to the plant’s No. 4 reactor. The company did not say how the workers died. But various news media reports say the men lost blood and went into shock.

“It pains me that these two young workers were trying to protect the power plant while being hit by the earthquake and tsunami,” Tokyo Electric’s chairman, Tsunehisa Katsumata, said in a statement, according to The Associated Press.

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Tokyo Electric Power Co. said Saturday that a cracked storage pit at the Fukushima No. 1 power plant was the source of a radioactive water leak contaminating the ocean and that it is attempting to fill it with concrete.
According to the utility and the Nuclear and Industrial Safety Agency, the square, concrete-covered pit is situated near an intake used to pump seawater into reactor No. 2.
Although the pit is small, it contains highly contaminated water with a radioactivity exceeding 1,000 millisieverts per hour that is leaking into the ocean from a 20-cm crack, Tepco said.
The pit, which is 1.2 meters x 1.9 meters and 2 meters deep, is usually used to store cables. But it is also connected directly to the reactor building through a cable trench, raising the possibility that the source of the contaminated water is the reactor itself, a NISA official said.
The cable trench is different from the pipe trench at No. 2, where water with the same level of radioactivity was discovered Monday. Although the two trenches are connected, no water has been found in the cable trench because it is at a higher elevation, the official said.
How much water has leaked and for how long were not known as of Saturday afternoon.
NISA spokesman Hidehiko Nishiyama said Tepco has been told to make sure there are no other leaks near reactor No. 2 and to strengthen is monitoring of seawater.

http://search.japantimes.co.jp/cgi-bin/nn20110403a1.html

There is a diagram of the location of the leak at the link.

Of course this should actually be called the path of the leak, not the source, which presumably is some breach in the reactor or pipework.
Blocking this will stop much or all of the drain to the sea though.

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@Leo Hansen, on 3 April 2011 at 11:54 AM said:

“NR99: you can see for yourself what the “modelers” have said. It’s more an explanation of what they think the accident progression was in R1 to R4, instead of a prediction of hysterical situations.”

I did *not* say that the modelers were predicting hysterical situations. I read the article; the predictions were along the lines of what has been discussed here since the early days of the event although the article implies the modelers very early predictions were more along the lines of what we know now than Barry’s early predictions, for example.

Some models may have been very wrong. For example, the NRC Chairman’s announcement that SPF4 was bone dry and on fire has been shown, to the extent we understand things, to have been very wrong. I can only assume he was working from a model although he never disclosed the basis for his assertion (this discussed previously on the comments here in other threads).

I suggested the *media* (not the modelers) would hype the various model predictions into “doomsday is here as a fact”.

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@NR99 I stand corrected, your comment was about the media, not about the modelers.

BTW, I agree with you about models, having worked with them for years. We have a saying “All models are wrong, but some models are useful.”

Your comment is I think especially true about climate models, climate modelers and the MSM: ” I would argue that the output of those models are not “known facts”, they are simply the speculations of the modelers, who fortunately have rarely had a chance to test their models.

I can only imagine the hysteria that would be generated by the media, turning model *predictions* into certain facts and certain fates, and cherry picking model predictions.”

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> Blocking … the drain to the sea …

Has anyone seen estimates of the volume of water that’s been going out via this path? It sounds like a lot did; the crack must date back to the earthquake (or earlier, and opened wide with the earthquake) so it may have served as a drain for a long time.

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IAEA: Unit 1 variable pressure; Unit 2 at atmospheric pressure; Unit 3 no pressure given.
http://www.iaea.org/press/?p=1916#more-1916

“… TEPCO announced on 2nd April that, following the detection of highly contaminated water leaking through a crack found in a pit near Unit 2, they had added 3 additional sampling points at 15km from Fukushima Daiichi and Fukushima Daiini….”

[Can they locate and collect the water flowing out of the crack at the downstream end?]

“In Unit 1 the indicated temperature at the feed water nozzle of the RPV is relatively stable at 259oC and at the bottom of RPV at 117oC. The RPV pressure indications are fluctuating and Drywell pressure is slightly decreasing. In Unit 2 the indicated temperature at the feed water nozzle of the RPV has decreased slightly from 161oC to 153oC. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is stable at 118oC and at the bottom of the RPV is about 92oC. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation….”

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From the same IAEA report:

“On 2 April, measurements were made at 7 locations at distances of 32 to 62 km, North and Northwest to the Fukushima nuclear power plant. The dose rates ranged from 0.6 to 4.5 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.09 to 0.46 megabecquerel per square metre….”

Anyone able to evaluate “beta-gamma … megabecquerel per square meter” numbers? Should that have a time associated with it as well as an area? Why are beta and gamma combined?

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An explanation of the terms (from a report on radioactivity left from some of the earliest research work done on radiation, by Rutherford)

Click to access ea-6-2009.pdf

“… The rate at which spontaneous transformations occur in a given amount of a radioactive
material (radioactive decay) is known as its activity. Activity is expressed in a unit called the Becquerel which has the symbol Bq, where 1 Bq is equal to one transformation per second. As for the unit of energy, multiples of the Bq are often used to describe the number of transformations that a radioactive material will undergo, with 1 million transformations being expressed as a mega-Becquerel (MBq)
…
“Becquerel (Bq)
The international (SI) unit for the number of nuclear disintegrations occurring per unit time, in a quantity of radioactive material. 1 Bq = 1 radioactive disintegration per second. This is an extremely small unit and levels are often prefixed with mega (106 Bq – MBq), giga (109 Bq – GBq) and tera (1012 Bq – TBq) particularly in the context of discharges of activity into the environment. Conversely, under normal circumstances, activity concentrations in environmental materials are generally low and so prefixes such as milli (10-3 Bq – mBq) and micro (10-6 Bq – μBq) are used…”

This is part of a rather thorough academic explanation of the longterm exposures over the lifetime of the various decay chains from each source. I recommend it, from paging through several of the documents, as a likely good reference for explaining this. Many of the popular press explanations either ignore radioactive decay or else give the mistaken impression that one thing goes away without mentioning that some of the decay products are also radioactive with their own decay paths, so utterly fail to explain dosage over time. These papers get that clear.

http://www.manchester.ac.uk/rutherfordreview/

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2nd Attempt at blocking crack underway using expanding gel:

‘Workers on Sunday poured a chemical compound mixed with sawdust and newspaper into a crack at Japan’s Fukushima Daiichi nuclear power facility that’s been a conduit for highly radioactive water leaking into the Pacific Ocean, a utility company official said.
This follows an unsuccessful attempt a day earlier to use concrete to plug the 2-meter-deep (6.5-foot-deep), concrete-lined basin, where authorities had found water gushing directly into the sea via a roughly 20-centimeter crack.
Eighty bags of a water-gel mix made by the Tokyo-based IB Daiwa company will be used in the operation. Each one contains 100 grams of material that includes a special polymer. A Tokyo Electric official said the substance should expand to several thousand times its size as it sticks, ideally, to plug the leak.
The cracked shaft sits behind the No. 2 reactor’s turbine building at the facility, which has been in constant crisis since the failure of cooling systems and numerous explosions in the wake of last month’s epic earthquake and tsunami.
Fixing the problem quickly is critical because officials believe it is one source of alarmingly high levels of radiation spotted in seawater near the plant. ‘
http://edition.cnn.com/2011/WORLD/asiapcf/04/03/japan.nuclear.reactors/index.html?hpt=T2

The importance of this is presumably obvious.

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I have apparently been marked out for approval before posting although at no stage was I rude, and simply asked for clarification of what was wanted, which as I stated is fine by me whatever the requirements are providing I understand them.
Since I have simply posted information which was not on the site already I am happy to continue to do so.
I appreciate that moderation has been fraught, but should I find that the next update I attempt to post is singled out for moderation before posting I will assume that they are no longer wanted, and regrettably will no longer post to this blog.
I wish all concerned all the best for the future.
MODERATOR
You have been put on the Pending list so that your incoming comments can be assessed for the new “Citing literature and other sources” commenting rule. You commented over-night Australian time so your comment has been held-up until Barry is on the blog. As Moderator I think your latest comment breaks the new rule but, as I am still getting used to it, I think we should await Barry’s decision.

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@Leo Hansen, on 3 April 2011 at 11:22 PM said:

Another interesting example of models… for decades astronomers have been modeling the expected characteristics of other solar systems but until fairly recently no one had actually seen an exoplanet so the models were constructed totally “blind”, except for the one sample that was known – our solar system.

Those models describe in great detail exactly how nebular material supposedly coagulates into a solar system. Some models even feature fancy computer graphics to illustrate the process in great detail.

As I understand it, the preponderance of the models, if not all of them, suggested other solar systems would look very much like ours with gas giants at the outer areas of the solar system with smaller rocky planets closer to the star.

In the last few years many exoplanets have been discovered and very recently some surprisingly small exoplanets have been discovered (something I find absolutely amazing).

The common thread that has surfaced is that none of these solar systems look anything like ours :-). All the models are very, very wrong. The consensus conclusion, as I understand it, is that although the models are “based on hard science” and physics is physics, the models were all seriously biased by the one example we know.

It would not be surprising that, months or a few years from now, after the cameras are finally lowered into these reactors and long term radiation studies are conducted, , all those forensic models will get some serious changes.

This is nothing like TMI, which was a PWR that sustained a single LOCA event over a 12-14 hour period. In this case you have a BWR that has sustained various degrees of a LOCA (really a loss of power event) over several weeks. But unlike TMI, the onsite engineers likely understood very well what was happening at each stage, they just didn’t have the tools to control it.

The current models are probably very biased toward the particulars of TMI since that is the only real life sample they have (of a major commercial reactor failure), not counting Chernobyl because the circumstances, engineering and equipment were so different and unlikely to be repeated.

A stopped clock is right twice a day, every day. Any journalist can construct a story about highly accurate stopped clocks. He simply has to cherry pick his clocks and the time he measures them.

Especially given the secrecy surrounding those models (per the article), we will never know how many of those models turned out wrong (and the results buried for good reason), based on what is known at this point in time or in the future. It’s easy to write a story about accurate models when you have the benefit of hind sight at some certain point in time, as we have now to some extent.

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NR99- Having had Geoff Marcy as a Professor (in Astrophysics post retirement) let me suggest that our current methods are skewed towards detecting giant plants circling close to stars. This is by the doppler shift method.

As such,our current understanding of the distribution of plantetary systems is at thistime is crude. I agree that we should not have believed that our plantetary aranngement is typical.

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I have been wondering why it’s so far not been possible to get the reactor vessels full of water or to stay full (having just read that they’re getting ready to introduce pure nitrogen to reduce the risk of a hydrogen-oxygen reaction inside the vessel, makes me think there’s no expectation of being able to fill the space entirely with water and keep it full.

Has anyone seen comments or information about this question anywhere?

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The pressure boundaries on PCVs #2 and #3 appear to leaking since they are running at atmospheric pressure. It was widely reported/speculated that #2 is leaking at or near the torus. Not sure where #3 is leaking. If they were to flood the PCV the static pressure head at the torus would be about 20 m = 4 atm which is the design pressure of the PCV. Maybe they can flood #1 since it holds pressure but unless they can repair the pressure boundary I doubt that they could flood #2 or #3.

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Hank Roberts, on 4 April 2011 at 10:56 AM — Introducing nitrogen strikes this amateur as a wise precaution. I don’t see that this precludes a future attempt to fill the reactors with water.

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Leo, I understand very well that the exoplanet data is necessarily skewed towards large planets (but see below!).

What broke the models, though, was the fact that many very large (presumably gas giant) planets are located very close to the stars, close enough to result in orbits in the order of a few days. The models all predicted that those gas giants must be very distant, like Jupiter and Saturn, with orbital periods measured in many years.

If you take a look at this chart of Exoplanets:

http://exoplanets.org/table/

You see very massive planets – greater than 1 Jupiter mass – msin(i) – with very short orbital periods, some only a few days, placing them well inside the orbit of Mercury.

You also see planets with as little as 0.02 Jupiter masses, which is only about 8x Earth’s mass. They are making great progress locating smaller planets- far greater than was expected only a few years ago.

My main point, though, is that in general models work well when the outputs are well understood and well observed in the real world. They work progressively more poorly when the outputs are not well observed and understood.

I suspect nuclear engineers know more about reactor behavior than astronomers know about exoplanets simply because they have blown a few up in the early years (this was discussed in a recent thread). And the physics may be simpler and more predictable- to some degree I do think the context holds, though, to some extenht. I’m not convinced climatologist modelers know much more, on a relative basis, than the astronomers, but that’s another discussion :-).
MODERATOR
Off-topic(as you say) – please move to Open Thread. Off-topic comments may be deleted as per BNC comment policy.

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David, I quite agree filling the air space with nitrogen makes sense. I don’t know if it’s a routine procedure delayed due to the earthquake (perhaps they didn’t have tanks of nitrogen on hand?) — or if it’s an unusual procedure entered into because they have concluded for whatever reason that they can’t get the containments to fill up anytime soon.

My question is has anyone seen any clear answer to why they haven’t been able to get the containments to fill up, up to the level where they were normally expected to be? Different answers for each reactor, or a replicated failure?

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Hank Roberts, on 4 April 2011 at 12:09 PM — I have no idea how routine adding nitrogen might be, but I’ll opine it is not.

I’ll also opine that #2 and #3 may have leaks. If so, those will need mending before the reactor container will hold water without incessant pumping.

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At this point the partial pressure of oxygen in the PCV should be approaching zero. The gas phase should be water only. Even if hydrogen is generated by oxidation of zircon by steam/water there will be no oxygen in the vessel to react with it. As long as any hydrogen is vented to the atmosphere outside of the rector building, it should not pose an explosion hazard.

Additionally, introducing nitrogen would add another significant hazard, i.e. the possibility of oxygen depletion in the environment where workers are present.

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Could they be preparing nitrogen injections because they need to pause water flow in order to repair the torus / cooling systems?

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Ernie, David and Hank: It’s my understanding that the PCV are normally inerted with N2, so that H2 explosions are minimized.

Although I doubt that zirconium-steam reactions are currently unlikely, radiolysis of water to produce both H2 and O2 is still taking place in the reactor. When the reactor PSV’s dump to the supression chamber, the H2 and O2 can build up over time in the PCV.

Typically it takes (at least with HC’s) a min O2 of ~ 8-10% for an explosion to take place. Over-inerting with N2 to keep O2 low is a common practice in the petroleum and tanker business.

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I’ve been very grateful to this discussion the issues around the efforts to contain the reactors in Japan. The amounts of “highly contaminated water” reaching the ocean are receiving a lot of attention. Can anyone offer details of the risks this may actually pose, absent the expansive doom reverberating through the media?

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Question for anyone who actually knows the hardware: The IAEA says:

“… In Unit 1 Fresh water has been continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using off-site power. In Unit 2 and Unit 3 fresh water is being injected continuously into the reactor pressure vessels through the fire extinguisher line indicated rates of 8 m3/h and 7 m3/h respectively …”

and then says

“In Unit 1 … The RPV pressure indications are fluctuating and Drywell pressure is slightly increasing. The reliability of RPV pressure indications is in question.
In Unit 2 …. Indicated Drywell pressure remains at atmospheric pressure.
In Unit 3 [no pressure given]”

I’d think they would have a pressure gauge on the pumps putting water into the RPVs and could figure out the pressure against which they are pushing water into Unit 1, to evaluate the sensor; just stop the pump momentarily, close a valve and see how much the reactor is pushing back.

Maybe not — if there’s a one-way valve in the system stopping backflow for example. That’s what I’m wondering. (I don’t expect to be told even if they do have them — I’m just wondering if it makes sense they’d have this info source, in addition to the pressure sensors originally installed that are dubious or dead.)

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Hank: A UCS file shows 2 isolation valves on the steam and 2 check valves on the main feedwater line (to prevent backflow). The two valves are 1 inside PCV and 1 outside.

I’d expect that fire extinguisher line would also have 2 check valves, but I have never seen a fire extinguish line on any of the simple BWR dwgs.

Re figuring out what pressure the reactor is at, one could back down the flow from the pumps and the indicated pressure at low flow would be the reactor pressure after adjusting for differences in height (static head)

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FEPC update, 4 April:

• Radiation Levels
o The level of concentration of radioactive nuclide I-131 (2.5 x 101 Bq/cm3) from the seawater sampled near the seawater discharge point of Fukushima Daiichi Nuclear Station at 1:50PM (JST) on April 3 was approximately 625 times higher than the maximum permissible water concentration (4.0 x 10-2 Bq/cm3) set by the government.
o On April 4, TEPCO announced that it will discharge 10,000 tons of low level radioactive water stored at the Central Radioactive Waste Disposal Facility in order to accommodate higher level radioactive water. It will also discharge 1,500 tons of low level radioactive water which had accumulated at the sub-drain pits of Unit 5 and 6 in order to prevent important equipment of Unit 5 and 6 from being submerged. The original TEPCO press release is attached and also available at:
http://www.tepco.co.jp/en/press/corp-com/release/11040404-e.html
(At 9:30PM on April 4, NHK reported the discharge of water from the Central Radioactive Waste Facility has commenced around 7:00PM and from the sub-drain pits at 9:00PM.)
o At 6:00PM on April 4, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 118 micro Sv/hour.
o At 6:00PM on April 4, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 72.1 micro Sv/hour.
o Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on April 4 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 2, lighting was restored at the part of the turbine building.
o At 7:20AM on April 4, the temperature of the spent fuel pool by thermography measurement: 64.4 degrees Fahrenheit.
o At 11:00AM on April 4, pressure inside the reactor core: 0.299MPa.
o At 11:00AM on April 4, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
o At 11:00AM on April 4, pressure inside the primary containment vessel: 0.15MPaabs.
o At 11:00AM on April 4, the temperature of the reactor vessel measured at the water supply nozzle: 469.0 degrees Fahrenheit.
o As of 3:00PM on April 4, the injection of freshwater into the reactor core continues.
o As of 7:00PM on April 4, preparation to recover and transfer the accumulated water at the turbine building continues.
• Fukushima Daiichi Unit 2 reactor
o On April 2, lighting was restored at the part of the turbine building.
o On April 2, monitoring cameras were set at the trench outside the turbine building and at the basement floor of the turbine building to monitor the water levels.
o At 9:30AM on April 2, the accumulated water was found in the pit (a vertical portion of an underground structure for housing electric cables) near the seawater intake and the radiation level of the water was over 1,000 milli Sv/hour. In addition, the water was observed entering the ocean from a crack (about 20cm = 7.9 inches) on the lateral surface of the pit.
o At 4:25PM on April 2, concrete was injected into the pit in an attempt to stop the discharging of water. (injected again at 7:02PM)
o At 1:47PM on April 3, polymer absorber, sawdust, and shredded newspapers were inserted in the pit in an attempt to stop the overflow of the discharge of water, until 2:30PM.
o At 7:08AM on April 4, tracer (white colored bath agent) was inserted into the trench outside the turbine building to determine the route of the water leakage.
o At 11:00AM on April 4, pressure inside the reactor core: -0.018MPa.
o At 11:00AM on April 4, water level inside the reactor core: 1.5 meters below the top of the fuel rods.
o At 11:00AM on April 4, pressure inside the primary containment vessel: 0.10MPaabs.
o At 11:00AM on April 4, the temperature of the reactor vessel measured at the water supply nozzle: 282.2 degrees Fahrenheit.
o At 11:00AM on April 4, the temperature of the spent fuel pool: 122 degrees Fahrenheit.
o As of 3:00PM on April 4, the injection of freshwater into the reactor core continues.
o As of 7:00PM on April 4, preparation to recover and transfer the accumulated water at the turbine building continues.
• Fukushima Daiichi Unit 3 reactor
o On April 2, lighting was restored at the part of the turbine building.
o At 9:52PM on April 2, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 12:54PM (approximately 75 tons in total).
o At 7:20AM on April 4, the temperature of the spent fuel pool by thermography measurement: 134.6 degrees Fahrenheit.
o At 9:30AM on April 4, pressure inside the reactor core: 0.005MPa.
o At 9:30AM on April 4, water level inside the reactor core: 1.75 meters below the top of the fuel rods.
o At 9:30AM on April 4, pressure inside the primary containment vessel: 0.1069MPaabs.
o At 9:30AM on April 4, the temperature of the reactor vessel measured at the water supply nozzle: 194 degrees Fahrenheit. (This figure is under investigation.)
o As of 3:00PM on April 4, the injection of freshwater into the reactor core continues.
o At 5:03PM on April 4, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete.
o As of 7:00PM on April 4, preparation to recover and transfer the accumulated water at the turbine building continues.
o As of 7:00PM on April 4, approximately 4,908 tons of water in total has been shot into the spent fuel storage pool.
• Fukushima Daiichi Unit 4 reactor
o On April 2, lighting was restored at the part of the turbine building.
o At 5:14PM on April 3, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 10:16PM (approximately 180 tons in total).
o At 7:20AM on April 4, the temperature of the spent fuel pool by thermography measurement: 86 degrees Fahrenheit.
o As of 7:00PM on April 4, approximately 1,473.2 tons of water in total has been shot into the spent fuel storage pool.
• Fukushima Daiichi Unit 5 reactor
o At 2:00PM on April 4, the temperature of the spent fuel pool: 94.3 degrees Fahrenheit.
• Fukushima Daiichi Unit 6 reactor
o At 2:00PM on April 4, the temperature of the spent fuel pool: 70.7 degrees Fahrenheit.
• Fukushima Daiichi Common Spent Fuel Pool
o At 8:10AM on April 3, the temperature of the spent fuel pool: 89.6 degrees Fahrenheit.
• Others
o At 9:10AM on April 2, a US Military barge (No.2) carrying freshwater docked at the dedicated port at Fukushima Daiichi Nuclear Power Station, towed by a vessel of the Marine Self Defense Forces.
o At 10:20AM on April 2, transferring freshwater from the US Military barge (No.1) to a filtrate tank resumed, until 4:40PM.
o At 12:12PM on April 4, a US Military barge (No.2) carrying freshwater docked again at the dedicated port at Fukushima Daiichi Nuclear Power Station, after refilling the freshwater.

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, 5 April

(1) Discharge of low level radioactive accumulated water in the Fukushima Daiichi NPS to the sea

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

(3) Missing TEPCO Employees at Fukushima Daiichi 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) Discharge of low level radioactive accumulated water in the Fukushima Daiichi NPS to the sea

There is currently great amount of radioactive waste water in the turbine buildings of the Fukushima Daiichi NPS and especially the turbine building of Unit 2 has extremely high level radioactive waste water.

We think it is necessary to transfer the radioactive waste water to the Central Radioactive Waste Disposal Facility in order to store it in a stable condition. However, ten thousand tons of low level radioactive waste water has been already stored and we have to discharge the existing low level radioactive waste water to receive new liquids.
In addition, as low radioactive subsurface water is piling up in sub drain pits of Unit 5 and 6 and a part of subsurface water is running into buildings, important equipment to secure the safety of reactors will be submerged.

Based on the Section 1 of the Article 64 of the Nuclear Reactor Regulation Law, we have decided to discharge to the sea approximately ten thousand tons of the accumulated low level radioactive water and a total of 1,500 tons of the low level radioactive subsurface water stored in the sub drain pits of Unit 5 and 6.

We evaluate approximately 0.6 mSv of effective radioactive doses per year for adults as the impact on the discharge of the low radioactive waste water to the sea if they eat adjacent fish and seaweeds every day. The amount (0.6 mSv of effective radioactive doses per year) is one-forth of annual radioactive dose to which the general public is exposed in nature.

Afterwards, we were preparing to discharge the low radioactive waste water to the sea. We started discharging the low radioactive waste water stored in the Central Radioactive Waste Disposal Facility to the sea at 7:00 pm on April 4th. In addition, at 9:00 pm on April 4, we started discharging the low level radioactive subsurface water stored in the sub drain pits to the sea.

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

On April 2, at around 9:30 am, 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. Furthermore, there was a crack about 20 cm on the concrete lateral of the pit, from where the water in the pit was outflowing. At around 12:20 pm, we reaffirmed the event at the scene.

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 NPS for analysis.

In addition to seawater sampling conducted in the coastal areas of Fukushima Daiichi /Daini NPS (sampling conducted at 4 points), we have initiated additional seawater sampling at 3 points in the areas 15 km offshore from the relevant power stations. Taking into account the result of these monitoring, we are intending to conduct a comprehensive assessment.

In order to block the leakage, we have injected concrete to fill up the pit and close the crack. But it turned out that leakage into the sea still continues. Then we tried to plug the path by putting sawdust, polymer and newspaper into the path from the afternoon on April 3. The water still keep spilling into the sea. This morning (April 4th), from 7:08 to 7:11 am, tracer (opaque white powder) was poured into the pit through the horizontal shaft of the trench for seawater piping and began to investigate the water path. The amount of tracer power was approx 13kg.

We will investigate the influx route of contaminated water in the pit and implement necessary measures to prevent such influx.
*pit: a shaft made of concrete

(3) Missing TEPCO Employees at Fukushima Daiichi NPS

Due to the Tohoku-Taiheiyou-Oki Earthquake which occurred on March 11th 2011, two TEPCO employees, who had been working at the turbine building of Unit 4 for site investigation, went missing.

We had put all our efforts to search them, and approximately at 3:25 pm and at 3:53 pm, March 30, those employees were found at the basement of the turbine building and we confirmed their death on March 31.

We would like to offer our deep regret that our employees died while working at the plant and heartfelt condolences to the bereaved families.

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MODERATOR
Please note that off-topic comments will be deleted and, as we are unable to transfer comments, you will be asked to re-post in the correct thread. In particular comments regarding your personal opinions, beliefs etc should be posted in the Fukushima Philosophical Open Thread.

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thanks for the update, but an important information about cesium in the sea seems to be missing:

but it has been reported in media, like the nytimes:

“The announced standards for fish came hours after the Tokyo Electric Power Company said it found radioactive iodine 131 in seawater samples collected to be 200,000 becquerels per cubic centimeter, or five million times the legal limit. The samples were collected Monday near the water intake of the No. 2 reactor of the Daiichi plant.

The sample also showed levels of cesium 137 to be 1.1 million times the legal limit, according to the public broadcaster NHK. Cesium remains in the environment for centuries, losing half its strength every 30 years. ”

[deleted personal scientific assessment not borne out by reference quoted.]

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