Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[rowmag]

new data from Tepco website on underground water contamination:

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110419e11.pdf

and pdf with time curves for all reactors samples:

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110419e12.pdf

Updated plots:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf

Looks like the I-131/CS-137 ratio is not changing at Unit 2...

 

[jarvik]

Well, maybe i should have written maximal ALLOWED dose for general population (defined by french safety coden but that is the limit in many countries for artificial radiation). Which i expect is a "safe limit" by the way ;o)

Fred has gone over much of your other text already but I thought you might like to know something further about what actually might be considered a "unsafe" exposure to radiation, as in one that we actually have reason to believe there could be health effects down the road.

From the 3rd table in the sourced linked below:

"100 mSv/year is the lowest level at which any increase in cancer is clearly evident. Above this, the probability of cancer occurrence (rather than the severity) is assumed to increase with dose. Allowable short-term dose for emergency workers taking vital remedial actions (IAEA)"

So a yearly exposure of 100mSv/year or 10,000 mrem /year is likely a more realistic safe limit that if crossed we can expect ramifications to human health to occur with some degree of certainty.

While it is certainly prudent to ensure that public exposure is well below this level and by a healthy margin, which I might add is what the 1 mSv/year guideline is meant to achieve. However it most certainly does not indicate that we need to be panicking the moment 1 mSv /yr is exceeded as it's well short of what we actually expect to be a dangerous level of exposure.

So again this is a bad situation that warrants alot of concern and yes if possible be over cautious with regards to public health (i.e.. try to get children and others out of the red zone NW of the current exclusion zone) but keep in mind evacuation has its own consequences to human welfare that might in this case be a greater likelihood of causing harm than exposure to a level of radiation that is somewhere in the area of 1/5th of the level expected to cause some measurable degree of long-term health effects. We don't have all the facts and additional complications that impact the decisions being made here.

There's lot we don't know about this situation and perhaps it is worse than we are lead to believe but having real information and knowledge is the only way to make headway and not jump at every shadow would be my preferred path.

http://www.world-nuclear.org/info/inf05.html"

 

[dinorobo]

It seems that this accident is gradually worsening, with no coherent strategy to resolve it.
The public parameters certainly show deterioration, with the closing of the immediate 20km zone and the extension of the contaminated zone to the north.
Also, while the official charts summarized here: http://fleep.com/earthquake/ show a reassuring steady decay of the measured contamination, the level privately monitored here http://www.ustream.tv/channel/%E6%94%BE%E5%B0%84%E7%B7%9A%E3%83%AC%E3%83%99%E3%83%AB from Chiba has about tripled since the April 19-21 inland wind and rain, to about 30 microsieverts/hr.
It does seem that the analogy to the frog being slowly boiled is not entirely off the mark.
Must a larger part of Japan become uninhabitable before the Japanese leadership recognizes that the current approach is not working?

That is not 30 microsieverts/hr, it is 0.30/hr

 

[tsutsuji]

...

Another private monitoring in Chiba prefecture : http://www.ustream.tv/channel/%E6%94%BE%E5%B0%84%E7%B7%9A%E6%B8%AC%E5%AE%9A-%E5%8D%83%E8%91%89 (about 0.150 μSv/h right now)

In Fukushima city : http://www.ustream.tv/channel/%E7%A6%8F%E5%B3%B6%E5%B8%82-%E6%94%BE%E5%B0%84%E7%B7%9A%E6%B8%AC%E5%AE%9A%E5%80%A4 (0.600 μSv/h right now)

More private monitoring channels at http://bearishtrader.blogspot.com/p/santa-monica-west-la-live-radiation.html

 

[jarvik]

It seems that this accident is gradually worsening, with no coherent strategy to resolve it.
The public parameters certainly show deterioration, with the closing of the immediate 20km zone and the extension of the contaminated zone to the north.
Also, while the official charts summarized here: http://fleep.com/earthquake/ show a reassuring steady decay of the measured contamination, the level privately monitored here http://www.ustream.tv/channel/%E6%94%BE%E5%B0%84%E7%B7%9A%E3%83%AC%E3%83%99%E3%83%AB from Chiba has about tripled since the April 19-21 inland wind and rain, to about 30 microsieverts/hr.
It does seem that the analogy to the frog being slowly boiled is not entirely off the mark.
Must a larger part of Japan become uninhabitable before the Japanese leadership recognizes that the current approach is not working?

So let's think about this a bit, 0.30 microSv/ hr or 7.2 microSv/ day works out to 2.63 milli Sv/yr or the extra exposure an Englishmen would get from moving to and living in France for a year.

 

[Dmytry]

You mean, leading to "natural" isotope separation causing nests of criticality?

No, not isotope separation. It really ain't going to happen that e.g. u235 would be separated from u238. Chemical element separation. Plutonium is a different chemical element, and it's compounds got different melting temperature from that of uranium, etc.

 

[mscharisma]

Getting KHG or something similar in there would have been my first task.
Instead, PackBots, T-Hawk and "Technicians" who can't even work with counters.

It's freaking me out, Japan isn't some 3rd world country, is it?

I KNOW I read somewhere yesterday that they are bringing in Japan-made robots that are much more sophisticated in their abilities (sorry, the technical details were beyond me, so I can't retell the story). Unfortunately, for the life of me, I can't find where I read it. Will post it when I come across it. Whatever I read said they would try and start operating these robots on Friday, i.e., today.

UPDATE: It's not the article I read yesterday, but here's info on the next step regarding robots:
http://search.japantimes.co.jp/cgi-bin/nn20110423f1.html

 

[etudiant]

So let's think about this a bit, 0.30 microSv/ hr or 7.2 microSv/ day works out to 2.63 milli Sv/yr or the extra exposure an Englishmen would get from moving to and living in France for a year.

Thank you.
It is good news to get this corrected info.
The larger point however is not altered, the exclusion zone is growing and the progress is desultory, with no coherent management evident.
The NRC characterization of the situation as 'static but fragile' conspicuously avoids using the word 'stable' that was reported elsewhere.

 

[NUCENG]

Updated plots:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf

Looks like the I-131/CS-137 ratio is not changing at Unit 2...

I looked for another earlier or later sample of the sub drains as a sample point. If anyone has that information (concentrations of I-131 and Cs-137) at the same sample point it may give us some information. Without that information it is not possible to say very much. There is still at least 3E16 Bq of I-131 that was initially in the core but has not yet decayed. and about the same amount of Cs-137. If you sampled all of the release streams and the inventories in the RPV, Suppression chamber (wet and air) and the drywell you would expect that the ratio is around 1:1 at this time after shutdown. The samples you cite give an Iodine ratio of I/Cs of about 7:1. But without knowing how the I-131 and Cs have been transported you cannot predict what the ratio should be at a particular sample point. Again, Cs and I have opposite chemical valences and chemical interactions may have affected the two isotopes differently during their trip to the subdrain. The higher level of I-131 probably rules out the sample point having become acidic allowing I₂ gas to reevolve. Has the source of the sample been drained or concentrated by evaporation or boiling? Has the Cs plated out or settled well upstream of the sample point?

One thing you can look at to see if the ratio is completely out of wack compared to the other units. Unit 1 is about 4:1, Unit 3 is about 1:1, and Unit 4 is about 8:1. With that sort of spread I can't guess whether these numbers tell us anything for certain. Give me more data from the same sample points and it may start to be useful.

 

[AntonL]

M5.5 earthquake at 00:25AM April 23 is reported with epicenter 37.224°N, 140.981°E , which is 11km south of the Fukushima II Daini NPP and 22km sout of Fuukushima I Daichi NPP

 

[Samy24]

Updated plots:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf

Looks like the I-131/CS-137 ratio is not changing at Unit 2...

I did never belief the quotes of criticality events because most scientists told us that there is no evidence for that. But maybe I had to change my mind.

The graphs show roughly two half-lifes and if I do simple math rightly, not only unit 2 but also the readings of the underground water in the area of unit 3,4 and 5 do not fit.

If the places of measurement are the same over the timeline then it reminds me to three possibilities:

1. The amount of iodine at the meassure point increases over time but not the amount of Cs.
But how is this possible? Someone with chemistry knowledge?

2. The source of the contaminated water releases more I-131 than Cs over time.
Why? Is there still something melting an iod is released first?

3. The source of the contaminated water still generates I-131.

 

[Samy24]

I looked for another earlier or later sample of the sub drains as a sample point. If anyone has that information (concentrations of I-131 and Cs-137) at the same sample point it may give us some information. Without that information it is not possible to say very much. There is still at least 3E16 Bq of I-131 that was initially in the core but has not yet decayed. and about the same amount of Cs-137. If you sampled all of the release streams and the inventories in the RPV, Suppression chamber (wet and air) and the drywell you would expect that the ratio is around 1:1 at this time after shutdown. The samples you cite give an Iodine ratio of I/Cs of about 7:1. But without knowing how the I-131 and Cs have been transported you cannot predict what the ratio should be at a particular sample point. Again, Cs and I have opposite chemical valences and chemical interactions may have affected the two isotopes differently during their trip to the subdrain. The higher level of I-131 probably rules out the sample point having become acidic allowing I₂ gas to reevolve. Has the source of the sample been drained or concentrated by evaporation or boiling? Has the Cs plated out or settled well upstream of the sample point?

One thing you can look at to see if the ratio is completely out of wack compared to the other units. Unit 1 is about 4:1, Unit 3 is about 1:1, and Unit 4 is about 8:1. With that sort of spread I can't guess whether these numbers tell us anything for certain. Give me more data from the same sample points and it may start to be useful.

I do understand most of your view, but it is not the total ratio that I feel is wired, it is the fact that at the same measure point the ratio stay the same over time.

 

[jarvik]

Thank you.
It is good news to get this corrected info.
The larger point however is not altered, the exclusion zone is growing and the progress is desultory, with no coherent management evident.
The NRC characterization of the situation as 'static but fragile' conspicuously avoids using the word 'stable' that was reported elsewhere.

No problem.

I'm sure I haven't been following the situation as closely as many on this forum have been, but I to have not been impressed with how TEPCO appears to have been responding to the situation and the amount of information that is readily available leaves many un-answered questions and concerns.

Somedays I also get a bit panicky about numbers (and the reliablility of numbers) until I've had a chance to think a bit about their context and have tried to filter my fears through a bit of number crunching. That being said I don't envy the techs, engineers, scientists and policy makers having to deal with this situation and hope to hell they are more compentent than what TEPCO appears to have been in the first hours after the quake.

 

[NUCENG]

We digress off-topic for this thread, and for that I apologize. I certainly can't claim to be knowledgeable enough to debate this topic on a purely scientific basis with experts in the field. I will say that the "one ionizing particle, one cell, one mutation, one cancer" basis for LNT-based regulations seems overly conservative for practical purposes. One nail could cause one flat tire resulting in one accident resulting in one or more fatalities. But it is not appropriate to stringently regulate the nail industry because of this, nor to induce in the public an irrational fear of the absolute risks of death by nail.

Continuous exposure to low dose radiation is an environmental fact of life. Perhaps the nuclear industry is to be lauded for stringent safety regulations with nothing but good and appropriate intentions for doing so, and for following the most conservative approach with the LNT as a guideline. But in practical terms, IMO, it is may be overlooked that one potential harm from such a conservative approach is propagation of the public perception of an irrational fear of radiation - "Oh my God, one particle of radiation and I am at increased risk for cancer! Where's my lead shield?!

Tcups,

The nuclear industry assumes the LNT approach as a basis of applying ALARA (As Low As Reasonably Achievable) for workers. Basically the three principles of reducing exposure are Time, Distance and Shielding. You keep dose low by spending less time in a radiation area. You try to spend time away from hot spots or local sources wherever possible (distance) and You may install extra shielding to reduce dose. ALARA calculations are often tradeoffs in these principles. For instance by training on a mockup in a non-radiation error, technicians may be able to do the job faster. The people who install temporary shielding to reduce another technician's dose may themselves get more dose than the techician would get without the shielding.

That is for nuclear workers. We treat releases to the environment as a much greater concern. Most plants now have achieved zero-release standards for liquid releases by filtering and other waste processing methods. BWR airborne releases are closely monitored. We work hard to achieve zero defects in fuel because that is the quickest way to start raising the airborne release numbers. Finally out of purely economical reasons we try very hard to reduce the generation of solid waste. Solid waste disposal is very expensive and a huge NIMBY (Not in My Backyard) issue.

My lifetime dose is about 7.5 Rem (75 mSv). That dose was all received while in US Navy submarines and during training in a prototype reactor in Idaho. My lifetime dose from working in commercial nuclear plants is zero. (Admitedly, I haven't been involved in any accidents in those commercial plants.) All rumors to the contrary, but I'm not dead yet!

People have been praying for the operators at Fukushima who are working to stabilize the plants. They deserve our respect because they are taking a risk. But believe it or not in the early hours and days of the accident at TMI2, one of the problems they had was too many people in the control room making it hard to hear orders and creating distractions. People wanted to be there to help figure it out and get the plant into a safe condition. They finally had to order people out of the control room. Plants today have developed Emergency Response orgainzations and facilities outside of the control room to assist operators fighting an accident. The Techical Support Center is usually on site in a shelded and filtered area. The The Emergency Operations Center is located safely offsite and includes environmental monitoring, Communications with state and government organizations and provides a single point of information to the press. Another example of learning from experience.

 

[MadderDoc]

These two photos ...

are linked from the Tepco handout page. Above the links the page says:
"A picture taken from the concrete pumping vehicle, the spent fuel pool, Unit3, Fukushima Daiichi Nuclear Power Station
(pictured on April 14, 2011)"

The picture to the left I cannot recognize as having anything to do with unit 3 at all, nor indeed, a spent fuel pool. I am not sure this photo is even from the vicinity of unit 3.

The picture to the right appears to me as something that could very well be from unit 3, however that would be from the north end of the building, not at the spent fuel pool, which is situated in the south end of the buiding

I wonder if anyone might have been more successful than I, in an effort to locate the motives of these two photos?

For comparison, here's how the roof floor of unit 3 with its SFP (the greeny area) looked in Tepco's skyview from April 15th:

[URL]http://www.tepco.co.jp/en/news/110311/images/110415_1f_3_4.jpg[/URL]

 

[NUCENG]

I do understand most of your view, but it is not the total ratio that I feel is wired, it is the fact that at the same measure point the ratio stay the same over time.

The specific sample that was discussed was a liquid sample at the Unit 2 "Sub Drain" If you have the same sample point at a different time please point me to it as I asked in my post. As far as I know that was the only sample at that location so there is no time trend yet.

If you want me to look at ratios at another sample point for which we DO have time trend data, I will look at that for you. I am alert to possible recriticality, but have not yet seen anything convincing, such as confirmed neutron bursts, generation of new short-lived isotopes, and other possible indicators like evidence of corium concrete interaction, new releases of hydrogen, etc.

Assuming that recriticality is possible should prompt TEPCO to be monitoring these sorts of indicators. If they haven't seen it I wouldn't expect them to be reporting things that HAVEN'T gone wrong. I am not saying I can prove no recriticality. I say that recriticality is not needed to explain the measurements we see. But we should all keep looking.

I do hope that someone at TEPCO is monitoring this and other websites around the world. There have been some very good questions, and postulations here. Even one of the other posters who has basically accused me of lying about my experience and expertise has had one idea that I am looking at seriously. Dmytry has stated that having emergency generators and pumps available off site, with airlift capabilities would be a good way to keep some of the emergency backups now stored on site away from a major on-site problem such as earthquakes, site external flooding, or major storms like tornados or hurricanes. TEPCO had inadequate design to handle the 9.0 earthquake and the 14 m tsunami and lost all AC power. Having prepositioned generators and pumps available may have permitted them to be in place before the batteries were depleted. Flooding and hurricanes may prevent access early enough, but having that capability may certainly help in other events that could be imagined. Of course if Fukushima had a 15 m wall we might not even be here.

 

[PietKuip]

Tsutsuji, the link you provided for simulation of local oceanic currents and radioactive dispersion is great (i repost it: http://sirocco.omp.obs-mip.fr/outils/Symphonie/Produits/Japan/SymphoniePreviJapan.htm ).
[...]
I put also this extract of their explanation to set the limits of this simulation:

We do not know how much radionuclides have been injected, when they have been injected...

This is worrying. This French institute has been asked by the IAEA to do simulations on the plume in the Pacific, but they did not get any other data than what has been published in those endless reams of paper that Tepco publishes on its site.

 

[mscharisma]

...

If you want me to look at ratios at another sample point for which we DO have time trend data, I will look at that for you. I am alert to possible recriticality, but have not yet seen anything convincing, such as confirmed neutron bursts, generation of new short-lived isotopes, and other possible indicators like evidence of corium concrete interaction, new releases of hydrogen, etc.

Assuming that recriticality is possible should prompt TEPCO to be monitoring these sorts of indicators. If they haven't seen it I wouldn't expect them to be reporting things that HAVEN'T gone wrong. ...

Technical aspects are somewhat beyond me, but from a PR standpoint (more my field), TEPCO should IMHO very much report on bad things they haven't seen. What better news than "no new neutron bursts or evidence of corium concrete interaction" could there possibly be to quell - reasonable or unreasonable - fears? Personally, I find the lack of reporting of the "bad stuff" they have not found rather disconcerting. For more than one reason I find it difficult to imagine that they are not looking for these things, not at last because the Japanese government might/should require such info to plan further actions regarding the population affected by this accident.
Very opposite to the scientific approach, when it comes to PR, one rule of thumb certainly is that one often learns more from the information not provided than from the information given.

 

[Samy24]

The specific sample that was discussed was a liquid sample at the Unit 2 "Sub Drain" If you have the same sample point at a different time please point me to it as I asked in my post. As far as I know that was the only sample at that location so there is no time trend yet.

If you want me to look at ratios at another sample point for which we DO have time trend data, I will look at that for you. I am alert to possible recriticality, but have not yet seen anything convincing, such as confirmed neutron bursts, generation of new short-lived isotopes, and other possible indicators like evidence of corium concrete interaction, new releases of hydrogen, etc.

Assuming that recriticality is possible should prompt TEPCO to be monitoring these sorts of indicators. If they haven't seen it I wouldn't expect them to be reporting things that HAVEN'T gone wrong. I am not saying I can prove no recriticality. I say that recriticality is not needed to explain the measurements we see. But we should all keep looking.

I do hope that someone at TEPCO is monitoring this and other websites around the world. There have been some very good questions, and postulations here. Even one of the other posters who has basically accused me of lying about my experience and expertise has had one idea that I am looking at seriously. Dmytry has stated that having emergency generators and pumps available off site, with airlift capabilities would be a good way to keep some of the emergency backups now stored on site away from a major on-site problem such as earthquakes, site external flooding, or major storms like tornados or hurricanes. TEPCO had inadequate design to handle the 9.0 earthquake and the 14 m tsunami and lost all AC power. Having prepositioned generators and pumps available may have permitted them to be in place before the batteries were depleted. Flooding and hurricanes may prevent access early enough, but having that capability may certainly help in other events that could be imagined. Of course if Fukushima had a 15 m wall we might not even be here.

Here is the reference I'm talking about:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf"

On page two is the data of the subdrain below the unit 2 since the last two weeks.

 

[etudiant]

Technical aspects are somewhat beyond me, but from a PR standpoint (more my field), TEPCO should IMHO very much report on bad things they haven't seen. What better news than "no new neutron bursts or evidence of corium concrete interaction" could there possibly be to quell - reasonable or unreasonable - fears? Personally, I find the lack of reporting of the "bad stuff" they have not found rather disconcerting. For more than one reason I find it difficult to imagine that they are not looking for these things, not at last because the Japanese government might/should require such info to plan further actions regarding the population affected by this accident.
Very opposite to the scientific approach, when it comes to PR, one rule of thumb certainly is that one often learns more from the information not provided than from the information given.

The old Boeing approach was: 'If you can't hide it, paint it red'.
A recognition that it is always better to lead with the news than to react to them.
Maybe TEPCO will eventually understand that is a better option.

 

[Rive]

Please correct me if I'm wrong but I assume that every amount of radioactive iodine means some previously released heat (during a chain reaction), regardless of the type of the chain reaction - core at work or recriticality.

So huge amount of iodine means terrible amount of heat...

 

[biffvernon]

M5.5 earthquake at 00:25AM April 23 is reported with epicenter 37.224°N, 140.981°E , which is 11km south of the Fukushima II Daini NPP and 22km sout of Fuukushima I Daichi NPP

Followed by another at M4.9 nearby:
4.9 2011/04/22 16:27:41 37.137 144.085 40.4 OFF THE EAST COAST OF HONSHU, JAPAN
5.5 2011/04/22 15:25:20 37.224 140.981 35.8 EASTERN HONSHU, JAPAN

Times are UTC
Source: http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php

 

[jlduh]

Data results from soil sampling at Daichi plant -from the 4th and 7th of April-:

Gamma nucleides
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110422e14.pdf

Pu analysis
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110422e13.pdf

Uranium analysis
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110422e15.pdf

Sampling spots:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110422e16.pdfTime series of gamma dust nucleides in the air at Daichi plant:

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110422e9.pdf

 

[NUCENG]

Technical aspects are somewhat beyond me, but from a PR standpoint (more my field), TEPCO should IMHO very much report on bad things they haven't seen. What better news than "no new neutron bursts or evidence of corium concrete interaction" could there possibly be to quell - reasonable or unreasonable - fears? Personally, I find the lack of reporting of the "bad stuff" they have not found rather disconcerting. For more than one reason I find it difficult to imagine that they are not looking for these things, not at last because the Japanese government might/should require such info to plan further actions regarding the population affected by this accident.
Very opposite to the scientific approach, when it comes to PR, one rule of thumb certainly is that one often learns more from the information not provided than from the information given.

I understand your point. I would make a miserable PR representative, so I agree TEPCO could have made better communications a more successful PR strategy. They didn't and I understand that, too. If wishes was fishes we could feed the world. ;)

 

[zapperzero]

UPDATE: It's not the article I read yesterday, but here's info on the next step regarding robots:
http://search.japantimes.co.jp/cgi-bin/nn20110423f1.html

Thanks.

Executive summary:

No specialized Japanese robots and operators are available. Some robots were in various states of development, but the state funding ran out from lack of interest.

Japanese companies wish to be left to experiment with the carcass of Fukushima Dai-ichi so as to develop rad-hardened robot tech locally. This way, everyone can save face by not having to use gai-jin tech when the next disaster happens.

Robots from other countries have so far been shunned for this very reason (with the exception of the iRobots, which are not rad-hardened and can't be used for cleanup work anyway).

 

[Dmytry]

The specific sample that was discussed was a liquid sample at the Unit 2 "Sub Drain" If you have the same sample point at a different time please point me to it as I asked in my post. As far as I know that was the only sample at that location so there is no time trend yet.

If you want me to look at ratios at another sample point for which we DO have time trend data, I will look at that for you. I am alert to possible recriticality, but have not yet seen anything convincing, such as confirmed neutron bursts, generation of new short-lived isotopes, and other possible indicators like evidence of corium concrete interaction, new releases of hydrogen, etc.

Assuming that recriticality is possible should prompt TEPCO to be monitoring these sorts of indicators. If they haven't seen it I wouldn't expect them to be reporting things that HAVEN'T gone wrong. I am not saying I can prove no recriticality. I say that recriticality is not needed to explain the measurements we see. But we should all keep looking.

I do hope that someone at TEPCO is monitoring this and other websites around the world. There have been some very good questions, and postulations here. Even one of the other posters who has basically accused me of lying about my experience and expertise has had one idea that I am looking at seriously. Dmytry has stated that having emergency generators and pumps available off site, with airlift capabilities would be a good way to keep some of the emergency backups now stored on site away from a major on-site problem such as earthquakes, site external flooding, or major storms like tornados or hurricanes. TEPCO had inadequate design to handle the 9.0 earthquake and the 14 m tsunami and lost all AC power. Having prepositioned generators and pumps available may have permitted them to be in place before the batteries were depleted. Flooding and hurricanes may prevent access early enough, but having that capability may certainly help in other events that could be imagined. Of course if Fukushima had a 15 m wall we might not even be here.

for flood, helipad on the roof + connectors there. Just as there are connectors for fire trucks on the first floor, right? (German nuclear power plants have that AFAIK). Also there's RCIC that keeps reactor cooled for a bit of time (hours?).

Not accusing you of lying, really. You may well be a nuclear engineer all right, the thing is, I think I misunderstood your attitude about safety especially when it comes to things such as criticality. It appeared as if you have view that it has to be presumed that there is no criticality. Sorry if that is not what you meant and you were simply playing devil's advocate. IMO it has to be presumed that there is criticality if there might be criticality and you don't know. Just like you have to presume there will be criticality if there might be criticality, to avoid criticality accidents, and a lot of criticality accidents look to me like an example of violation of that approach.

You haven't offered some specific explanation of high iodine levels (highest of everything), yet you say it may be caused by something else. Well it might be, but for start one thing it can't be caused by:
CsI role in transport of Caesium : Caesium Iodide has something around 1360 Bq of iodine for 1 Bq of Caesium, so it cannot be that everywhere we have CsI leaking keeping the Cs to I ratio constant, to propose so is to be unaware of mol to Bq conversion.
Ditto for other caesium+iodine chemical compounds. Once again, I may have misunderstood your point on CsI, not sure why CsI was brought up, in the solution there is no CsI anyway, just the ions, so I thought you were explaining the ratio with CsI leaving the fuel.

Furthermore, there has to be a giant disparity between relative rates of transport of caesium and iodine from fuel into the water for the spent fuel pool #4 and for all the reactors. 3 orders of magnitude. While for 3 other reactors it is same order of magnitude (and same order of magnitude ratio as for Chernobyl i think, and TMI, but someone should check the numbers).
Why would it hit the spot where it is same order of magnitude as other reactors a few weeks ago? Luck?

re: TEPCO's actions. They used to check for short living isotopes. They published data with, of all things, Cl-38 . Then they published data with I-134 . Then TEPCO officials declared there is no criticality. Then they retracted the data where they had I-134 and claimed 3 orders of magnitude mistake (overestimating radioactivity). Then government official (Kan?) really harshly criticized them for measurement mistakes, with a lot of hollow words of how it puts worker lives at risk - keep in mind, that was TEPCO erring on the side of caution! edit: even worse, there were also many stupid words how it is unforgivable to release data without review. Then they released new data without I-134 and Cl-38 and the number of isotopes being tested for dropped sharply. It looks almost as if government is urging TEPCO to cover things up. I'm going to find references again tomorrow, it is late here and there's been so much news about the accident.

 

[PietKuip]

re: TEPCO's actions. They used to check for short living isotopes. They published data with, of all things, Cl-38 . Then they published data with I-134 . Then TEPCO officials declared there is no criticality. Then they retracted the data where they had I-134 and claimed 3 orders of magnitude mistake (overestimating radioactivity). Then government official (Kan?) really harshly criticized them for measurement mistakes, with a lot of hollow words of how it puts worker lives at risk - keep in mind, that was TEPCO erring on the side of caution! edit: even worse, there were also many stupid words how it is unforgivable to release data without review. Then they released new data without I-134 and Cl-38 and the number of isotopes being tested for dropped sharply. It looks almost as if government is urging TEPCO to cover things up. I'm going to find references again tomorrow, it is late here and there's been so much news about the accident.

The problem was that they recorded gamma spectra on samples that had been taken 10 hours before. The presence of isotopes with halflives of about an hour was impossible. But their software had extropolated noise backwards in time. In this case, there was no cover-up.

However, in the video of the English-language press conference, the Tepco engineers seemed to get evasive when there were questions about criticality. The only real statement they gave was that there is no criticality at Unit 1 right now. They referred to measurements by neutron detectors.

 

[Dmytry]

The problem was that they recorded gamma spectra on samples that had been taken 10 hours before. The presence of isotopes with halflives of about an hour was impossible. But their software had extropolated noise backwards in time. In this case, there was no cover-up.

10 times past half life it is 1/1024 . (Most curiously, btw, for SFP4 it is more than 10 times past half life for i-131)
Funky software they must have got, does backward extrapolation but doesn't give confidence value or anything. Also, of all stuff, Cl-38 . Theres lot of possible stuff not normally supposed to be present in the reactor, of all that stuff they found Cl-38 , not something entirely off the mark.

Also WTF 10 hours delay? KHG would have had a measurement van on site and would of done it in minutes.

However, in the video of the English-language press conference, the Tepco engineers seemed to get evasive when there were questions about criticality. The only real statement they gave was that there is no criticality at Unit 1 right now. They referred to measurements by neutron detectors.

Well indeed. And they take pool water sample, and only tell of i-131 and cs-137 . Why even bother taking sample then? To know if it is safe to drink?

 

[rowmag]

Give me more data from the same sample points and it may start to be useful.

I thought the link I gave (and Samy24 also) is to times series plots from the same sample points, covering a two-week span... Did I mess up the link somehow?

Here it is again:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf

 

[razzz]

NHK, Japan's national broadcaster, positioned a TV camera 33 kilometers southwest of the plant, and broadcast the helicopter operation live. At 9:48 a.m. local time a helicopter flying from the west dropped the first load of water almost directly over the No. 3 reactor, though a significant amount spread away from before reaching the target.

http://spectrum.ieee.org/tech-talk/energy/nuclear/helicopters-and-cannons-spray-water-on-japans-unstable-nuclear-plant" Field of view is about the same in this video after appox. 30secs as with the #3 explosion video. A good guess for syncing a sound track.

 

[NUCENG]

Here is the reference I'm talking about:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e16.pdf"

On page two is the data of the subdrain below the unit 2 since the last two weeks.

This is what I was looking for. You are right the ratio of I/Cs is not decreasing as we expect on the Unit 2 sub drain. In fact the ration is increasing the way I take data off those graphs.

Assumption: Samples were measured by the same method and have consistent accuracy.

Observations
1. On 4/7 and 4/14 rhe ratio was abroximately 16 0r 17:1 but both CS and I concentration increased by a factor of 10 during that week.
2. In the week after 4/14 Iodine concentration remained constant at about 160 to 170 Bq/cm³.
3. In the week after 4/14 Cs decreased from 10 Bq/cm³ to about 6 Bq/cm³.

Interpretations:
1. Clearly the sources feeding this sample point saw aditional releases of both Cs and I in the first week,
2. Since the concentration of I-131 did not decrease by one half in the second week it appears there was further release of I-131 during this second week. Since this is a liquid sample an increase in iodine means the liquid has probably remained at a basic pH and reevolution of I₂ gas is not significant. One possibility for new I-131 release would be criticality. however this would also likely be releasing additional Cs. That may explain the first week, but does not fit the results of the second week.
3. Cs-137 with its longer half life would not have been expected to decrease measurably in a week. since there was a decrease of about 40% some mechanism of Cs removal was present. Cs plateout or deposition upstream of the sample point is my best guess for the decrease in Cs during the second week.
4. First week and Second week are not directly comparable because there clearly were differnces in source and transport of Cs and I.
5. Data does not rule out recriticality during the first week.
6. Second week shows opposite behavior from expected results. Iodine concentration is not decreasing consistent with half life, and Cs is decreasing which is inconsistent with its half life.

To summarize: the time trend of Cs and I at the unit 2 sub drain sample point changed from the first week to the second week. Behavior appears to diverge from the expected decrease in I/Cs ratio.

 

[PietKuip]

Also, of all stuff, Cl-38 . Theres lot of possible stuff not normally supposed to be present in the reactor, of all that stuff they found Cl-38 , not something entirely off the mark.

Chlorine-38 would have been in the database of the software. Salt can get into the cooling water of a nuclear plant (sweat drops, and after all the sea is very close). So the software would look for something, and it found a noise peak.

Also WTF 10 hours delay? KHG would have had a measurement van on site and would of done it in minutes.

It was probably more important to get a measurent from officially certified equipment... Rules and regulations, you know.

 

[Dmytry]

nukeng: yea yea, it may be criticality there in reactors, it may be weird chemistry, who knows. Except, there you have order of 10 discrepancy, and in SFP #4 you have order of 10 thousands discrepancy, and you've been justifying possibility of explanation of latter with the former. What I don't understand is what difference does it make that there 'might' be other explanation than criticality. The criticality is possible and is a big deal, and they'd better either a: rule it out, or b: confirm it undeniably, and they don't seem to do either.
Is the difference that they might get lucky and it was just some weird chemistry? Well whatever. Counting on luck would be a terrible attitude imo.

Chlorine-38 would have been in the database of the software. Salt can get into the cooling water of a nuclear plant (sweat drops, and after all the sea is very close). So the software would look for something, and it found a noise peak.

Well what do you know about how they are doing spectrometry anyway? Is it pure speculation? The thing would detect trace amount of radioactive chlorine when those are from trace amounts of chlorine, but it won't detect larger amounts of radioactive chlorine when those are from pumping seawater, coz it's omg 10 half lifes. Then for omg 10 half lifes approach, you got the spent fuel pool #4 where iodine is well past 10 half lifes.

It was probably more important to get a measurent from officially certified equipment... Rules and regulations, you know.

lol. such rules is how you blow up. also, KHG van is certified for such highly contaminated dirty salt water with a lot of weird stuff in it, whereas whatever thing they use during normal operation is probably only certified for what plant encounters during normal operation.

 

[MiceAndMen]

Found an article in IEEE Spectrum that says Honeywell's T-Hawk drones took radiation measurements along with hours of (lousy IMO) video. TEPCO has yet to release any of that data.

http://spectrum.ieee.org/automaton/.../robotic-aerial-vehicle-at-fukushima-reactors

The flow of information is going to get much worse on Monday. That's when the Japanese government takes control of the public information releases and puts the muzzle on TEPCO. Foreign journalists and bloggers have so far been banned from the government press conferences. At the TEPCO affairs the foreign reporters are the only ones asking the tough questions. If they continue to keep the foreign press out of the loop at official government press points then the information flow will be reduced to a trickle.

 

[PietKuip]

Well what do you know about spectrometry anyway? Is it pure speculation? Sounds like it is.

I gave my name, and a link to my work pages. Teaching gamma spectrometry to physics students is one of the things I do. I know a bit about the errors that can be made.

http://www.tepco.co.jp/en/press/corp-com/release/11042008-e.html confirms what I said about the database. Their software came with a nuclide library. Short-lived Te-129 had not been listed there as a daughter nuclide of the metastable isomer.

In the re-evalution of their spectra, they looked for the main peaks of Cl-38, and did not see any. See http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110420e11.pdf for the reasons for change.