Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Shinjukusam]

You criticize the only two people (almost) that the establishment has allowed to put a message out there warning people of some of the dangers we may face. I like both of them because they can do it with a calm and controlled demeanor. Myself, when I try to tell people the physics of Fukushima, I seem frantic and hysterical.

So we should throw out scientific analysis and proof as long as the spokesman is calm and controlled? No, I don't think so. I listed the reasons that their testimony should be doubted, if you should choose to dismiss me then that's your prerogative.

 

[elektrownik]

Important: Tepco fixed one of reactor 2 water level indicators and... reactor 2 water level is down scale which mean that water level is at last 5m below top of fuel rods, so reactor could be dry

 

[gregtomko]

Gunderson is trying really, really hard to establish himself as the go-to guy as a talking head about nuclear issues. He is good at explaining things to non technical people

It looked to me like he was just trying to point out some facts that were not being addressed. Information is very tightly guarded around the Fukushima nuclear plant, so it looked to me like he was doing the best he could with what little was available. Everybody gets some things wrong some times.

Chris Busby: Complete fruitcake.

Thats kind of what my feeling was too, but at least an interesting fruitcake :-)

 

[SteveElbows]

You criticize the only two people (almost) that the establishment has allowed to put a message out there warning people of some of the dangers we may face. I like both of them because they can do it with a calm and controlled demeanor. Myself, when I try to tell people the physics of Fukushima, I seem frantic and hysterical.

Gunderson deserves even worse criticism than you see here recently. I don't care how calm he is, he went on about how he knew a thing or two about spent fuel pools, and then proceeded to analyse a video of unit 4 spent fuel pool in a very wrong way. He said the crane had fallen into the pool, and that fuel racks were exposed. He made little or no effort to correct this terrible inaccuracy later. Meanwhile other people who did not have his background or experience were able to look at the same video and reach much better conclusions.

 

[tsutsuji]

http://www.asahi.com/national/update/1018/TKY201110180453.html (18 October) there was a leak of high level contaminated water (290,000 Bq/cm³ of Cs 137) that was found on 18 October during maintenance at the Kurion system when workers entered the area to change a motor. The cause is investigated. The leaked water has already been pumped back to the concentrated waste treatement facility. With 3 tons, it is the second amount of leaked highly radioactive water after the 6 ton leak that occurred in June.

Or in Tepco's words:

- At around 11:00 am on October 18 we found approx. 15cm depth of accumulated
water (approx. 3m3 ) inside the skid, during motor replacement works of the pump
(H2-2) inside the skid of the suspended Cesium adsorption apparatus. We also confirm
that leaking stopped when we found. After that we suspended replacement work of
relative motor and started to drain of the accumulated water by submersible pump. The
cause is currently under investigation.
- At 9:06 pm on October 19, in the water treatment facilities under operation, a SMZ
pump of the 4th process line of cesium adsorption apparatus automatically stopped. A
pump of the 3rd process line is continuously operated. Water treatment by the cesium
adsorption apparatus is also continuously operated at the flow rate approx. 17m3/h (the
flow rate before the automatic stop was approx. 20m3/h).
http://www.tepco.co.jp/en/nu/fukushima-np/past-progress/images/newestfile-e.pdf

http://kyushu.yomiuri.co.jp/news/national/20111022-OYS1T00221.htm The reason of the automatic shutdown of Genkai NPP unit 4 on October 4 was a wrong instruction manual used during maintenance work at a system related with the condenser, Kyushu electric announced on 21 October. The workers removed a cable that supplied electric power to a valve. The degree of vacuum in the condenser declined and that triggered the automatic shutdown.

http://www.kyuden.co.jp/library/pdf/press/2011/111021b-2.pdf Kyushu electric's press release on Genkai unit 4's shutdown. The maintenance was the change of a torque switch at the main turbine gland steam valve. It is a a control cable (not a power cable) that was unplugged, and it resulted in a closure signal being transmitted to the gland steam control valves. It was the first time that this maintenance was done while the plant is running.

 

[Azby]

You criticize the only two people (almost) that the establishment has allowed to put a message out there warning people of some of the dangers we may face. I like both of them because they can do it with a calm and controlled demeanor. Myself, when I try to tell people the physics of Fukushima, I seem frantic and hysterical.

I would make even stronger criticisms of them both. The problem with Gundersen is that he's sometimes been right. But he continues to repeat speculation without substantiating it, even after others have proven him wrong, and I've never seen him retract anything (like the "unit 4 is leaning story"). And he continues to talk about a piece of fuel rod found over 1km away from the plant, but has never shown the evidence for that to my knowledge. As for Busby, the "science" behind his claims and risk estimates has been solidly debunked time and again, even by other anti-nukes and people who are inclined to want to support his positions. It's as bad as UFOlogy. Just because he seems like a nice guy and stands up to authority is no reason to accept his scientific opinion. Wrong is wrong, misleading is misleading, and disinformation is disinformation no matter what the source or motivation.

 

[hbjon]

Chris Busby is a fruitcake? Why? Because he says the stuff that was in those building was really really bad stuff, and it can kill ya? Because he uses the "bedtime story" approach at presenting this dreadfull information? Or is his science all wrong? He seems to think he knows what he is talking about. It is hard to get worried listening to him. I find myself going to sleep.

 

[tsutsuji]

"Tepco never pushed electrical safety plan at nuke plant":

Tokyo Electric Power Co. sources said while consideration had been given in 2006 to connecting all sources of electricity at all six reactors, no decision was made because of technical problems.
http://ajw.asahi.com/article/0311disaster/fukushima/AJ2011102315544

 

[LabratSR]

Unedited Fukushima accident manual released, loss of power sources not envisioned

http://mdn.mainichi.jp/mdnnews/news/20111025p2a00m0na007000c.html

 

[NUCENG]

Unedited Fukushima accident manual released, loss of power sources not envisioned

http://mdn.mainichi.jp/mdnnews/news/20111025p2a00m0na007000c.html

First question: What are the pressure limits and process requirements for venting? Did they follow their manual?

 

[LabratSR]

From the Japan Times article on the manuals.
http://www.japantimes.co.jp/text/nn20111026a1.html

"Instructions in the manuals were all based on the assumption that two backup direct current batteries at reactor 1 would keep working throughout any emergency. In fact, the batteries were knocked out by water when the monster tsunami struck and crippled the Fukushima plant.

The manuals also failed to instruct workers to open by hand critical valves normally powered by electricity to vent steam and thus reduce pressure in the containment vessel. The DC batteries were supposed to supply power to operate those valves.

The containment vessel is the last line of defense to prevent radioactive materials from escaping the reactors. Tepco tried to open the valves to keep the vessel from breaking apart on March 12. Pressure also needed to be reduced to allow coolant water to be injected to prevent a meltdown of the reactor core.

But it took hours for Tepco workers, who apparently had no training in how to open the valves manually, to vent the steam and relieve the pressure, and many experts say the delay may be a key factor that led to the meltdown at unit 1."

 

[Norman]

Interesting paper posted on the Xenon and Cesium releases from the disaster.

http://www.atmos-chem-phys-discuss.net/11/28319/2011/acpd-11-28319-2011.html

The paper states there is some evidence the that Xenon release happened very early correlating with the Earthquake and not the Tsunami damage.

 

[NUCENG]

From the Japan Times article on the manuals.
http://www.japantimes.co.jp/text/nn20111026a1.html

"Instructions in the manuals were all based on the assumption that two backup direct current batteries at reactor 1 would keep working throughout any emergency. In fact, the batteries were knocked out by water when the monster tsunami struck and crippled the Fukushima plant.

The manuals also failed to instruct workers to open by hand critical valves normally powered by electricity to vent steam and thus reduce pressure in the containment vessel. The DC batteries were supposed to supply power to operate those valves.

The containment vessel is the last line of defense to prevent radioactive materials from escaping the reactors. Tepco tried to open the valves to keep the vessel from breaking apart on March 12. Pressure also needed to be reduced to allow coolant water to be injected to prevent a meltdown of the reactor core.

But it took hours for Tepco workers, who apparently had no training in how to open the valves manually, to vent the steam and relieve the pressure, and many experts say the delay may be a key factor that led to the meltdown at unit 1."

That is possible. Venting would reduce pressure in containment and subsequently allow continued depressurization for the RPV. This would allow low pressure external fire pumps or trucks to make up water to the reactor. If melting was not already underway then delaying venting could be a key factor.

However, as I understand the timeline at unit 1 the Isolation Condenser had been tripped, there was no water makeup to the core, inventory was being lost due to the SRVs venting the vessel to containment, and containment was more than double its pressure rating for a period of hours. Under those conditions the core would have begun melting shortly after fuel was uncovered, increasing temperatures at a rate of about 1 degree per second. Once zirc water reactions start that is an exothermic reaction increasing boiloff and heating. A large part of the delay was to get government permission to vent. IMO, operator training for manual vent operation is a contributing cause but not at the top of the list. Operators did not have the authority to take action when it might have helped. Their emergency manuals may have been woefully inadequate, so naturally the training or lack of training on implementing the manual would be suspect. In short, the core was probably melting before they even tried to vent.

I know I have harped on this before, but even that wasn't the real root cause. Japanese industry and regulators built plants and then stopped looking. They ignored geological findings about earthquakes and tsunamis. They built up a regulatory system that left no one responsible. The repeated scandals of fudged paperwork and testing were warnings. The KK earthquake was a warning. Japanese attitudes that they didn't need to worry about 9/11 terror because Japan was a 'stable society' was a warning.

Was it complacency, or greed, or negligence, or incompetence? I know this is the technical thread, but in this case I am not sure the accident could have been prevented by any technical solutions.

 

[Astronuc]

Was it complacency, or greed, or negligence, or incompetence? I know this is the technical thread, but in this case I am not sure the accident could have been prevented by any technical solutions.

Certainly not after the fact.

The proactive actions of ensuring the protection of EDGs and their fuel supply, and ensuring the protection of the electrical lines from EDGs to the ECCS and safety systems, should have been a priority. Ensuring protection = prevention of flooding and prevention of failure due to seismic loads.

 

[Bandit127]

Interesting paper posted on the Xenon and Cesium releases from the disaster.

http://www.atmos-chem-phys-discuss.net/11/28319/2011/acpd-11-28319-2011.html

The paper states there is some evidence the that Xenon release happened very early correlating with the Earthquake and not the Tsunami damage.

An article in Nature about the same paper I think.
http://www.nature.com/news/2011/251011/full/478435a.html"

 

[clancy688]

Interesting paper posted on the Xenon and Cesium releases from the disaster.

http://www.atmos-chem-phys-discuss.net/11/28319/2011/acpd-11-28319-2011.html

Quoting from the description:

Altogether, we estimate that 6.4 TBq of 137Cs, or 19% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 TBq, or 2% of the total fallout were deposited on land areas other than Japan.

And if you look in the report, they estimate total C137 emissions of 35.8 PBq (uncertainty range from 23.3 - 50.1 PBq) which puts it to 42% of Chernobyl.
Does anyone remember the first INES-7 classification which stated something around 10%? Next came a revised number which was closer to 20% than to 10%. And now there's 40%? Just great...

But there's something not right with that report. 6.4 TBq is NOT 19% of 35.8 PBq. Moreover, 6.4 TBq of C137 isn't enough to contaminate Fukushima prefecture with those radiation levels which were measured. Not in the slightest. My guess is that they've either forgot a "thousand" or confused Tera with Peta...

 

[etudiant]

Quoting from the description:



And if you look in the report, they estimate total C137 emissions of 35.8 PBq (uncertainty range from 23.3 - 50.1 PBq) which puts it to 42% of Chernobyl.
Does anyone remember the first INES-7 classification which stated something around 10%? Next came a revised number which was closer to 20% than to 10%. And now there's 40%? Just great...

But there's something not right with that report. 6.4 TBq is NOT 19% of 35.8 PBq. Moreover, 6.4 TBq of C137 isn't enough to contaminate Fukushima prefecture with those radiation levels which were measured. Not in the slightest. My guess is that they've either forgot a "thousand" or confused Tera with Peta...

Presumably the emission total would rise noticeably beyond these airborne amounts if water borne quantities were included. Given the much larger quantities of nuclear fuel involved at Fukushima, it would in fact be surprising if the total emissions did not at least match those of Chernobyl.

 

[clancy688]

According to the report Xenon-33 releases are 2.5 times Chernobyl (16.7 EBq). Which's no wonder since there were three leaking reactors instead of just one.

Edit: NSC even scaled down its estimates to 11 PBq C-137:

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1315203996P.pdf So that new release estimate is three times the size of the official one.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111027/0700_miawase.html Tepco has decided to postpone the building of a water shielding wall on the land side. As a result of the study of ground water flows inside the plant site, it was concluded that there is little worry that the contaminated water would flow toward the mountain side. Conversely, if a wall is built on the mountain side, the ground water level will drop, and the probability that contaminated water leaks out will increase. The construction of the sea side wall starts on 28 October and will take about two years. The construction of a mountain side wall will be studied again after the completion of the sea side one.

 

[nikkkom]

I don't understand this underground wall building thing. Isn't it FAR easier to achieve the same by drilling wells and periodically (say, daily) pumping water out?

 

[etudiant]

I don't understand this underground wall building thing. Isn't it FAR easier to achieve the same by drilling wells and periodically (say, daily) pumping water out?

Maybe just a decision to go for a more robust solution?
Pumps have been known to fail.

Of course, building a watertight underground barrier in an area prone to sizable earthquakes is not exactly something anyone does routinely either. Temblors make concrete break, as we've seen.
A freeze barrier, which freezes a large stretch by piping in a chiller material such as liquid air might be more reliable, as the breaches in the wall would self heal, but would also still depend on sustained maintenance.

 

[LabratSR]

Fukushima Daiichi: Treatment of Contaminated Water 1
http://youtu.be/VOdqCA__fBk

 

[nikkkom]

Maybe just a decision to go for a more robust solution?
Pumps have been known to fail.

Pumps can be repaired. It's still cheaper than huge underground wall.

 

[LabratSR]

Video: Report from Fukushima Daiichi (second installment) October 21, 2011

http://youtu.be/AYjcT5WDkRw

 

[westfield]

I don't understand this underground wall building thing. Isn't it FAR easier to achieve the same by drilling wells and periodically (say, daily) pumping water out?

I'm not sure the aim is to lower the water table under the plant, it may actually be the opposite. Perhaps they are thinking that keeping the natural water table high may reduce leakage of contamined water from the various basements of the plant.

 

[zapperzero]

I'm not sure the aim is to lower the water table under the plant, it may actually be the opposite. Perhaps they are thinking that keeping the natural water table high may reduce leakage of contamined water from the various basements of the plant.

Well it makes sense that if it's going to leak anyway, you want fresh water leaking into the contaminated water, not the other way around.

 

[joewein]

Does anyone remember the first INES-7 classification which stated something around 10%? Next came a revised number which was closer to 20% than to 10%. And now there's 40%? Just great...

It was often claimed that the estimate had gone from 10% of Chernobyl in April to 20% in June, but that is not correct. There were two estimates in April at 7% and 12% by NISA and NSC respectively (an average of 10% I guess), the lower of which was updated to 14% in June. The initially higher one (by NSC) was not revised and there was never a 20% estimate by either NISA or NSC.

I agree with your comments about TBq vs PBq. They must have missed three zeros or switched the unit.

UPDATE: They have already published http://bit.ly/uuIEY4" for the summary in the comments section, explaining that they accidentally wrote TBq where they meant PBq.

 

[clancy688]

UPDATE: They have already published http://bit.ly/uuIEY4" for the summary in the comments section, explaining that they accidentally wrote TBq where they meant PBq.

LOL! That's my name there. I wrote G. Wotawa an email concerning those two values and he contacted the head scientist. I'm still a student so I never expected my name to appear in such an official paper. At least not yet. Feels nice... even if it's just a little comment. :)

 

[Azby]

LOL! That's my name there. I wrote G. Wotawa an email concerning those two values and he contacted the head scientist. I'm still a student so I never expected my name to appear in such an official paper. At least not yet. Feels nice... even if it's just a little comment. :)

Hooray for peer review! And this was kind of a biggie.

 

[tsutsuji]

http://www.aec.go.jp/jicst/NC/tyoki/sakutei/siryo/sochi5/index.htm List of the documents that were distributed during the 5th meeting of the middle and long term committee that was held on 28 October. The update of the middle and long term schedule is available on http://www.aec.go.jp/jicst/NC/tyoki/sakutei/siryo/sochi5/siryo3.pdf .

http://www.asahi.com/national/update/1028/TKY201110280512.html The middle and long term committee has disclosed a draft report :

2011: start of decommissioning
about 2014: start of pool fuel removal
about 2021: start of melted fuel removal
about 2026: end of melted fuel removal
2041 or later: end of decommissioning

http://news.tbs.co.jp/newseye/tbs_newseye4863985.html Two workers were injured at Fukushima Daiichi during the disassembly of the big crane that was used to build unit 1's cover. They were hit by a bundle of diameter 36 mm steel wire that fell down.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111028_01-e.pdf Cracks were found on a part of the ceiling crane at the the common fuel pool.

http://www3.nhk.or.jp/news/html/20111028/t10013582051000.html Three similar cracks had been found on crane axles at Kashiwazaki-Kariwa after the 2007 earthquake. As the common fuel pool must be used within 3 years during the removal of fuel from reactor building pools, Tepco will change the broken parts.

http://www.mbs.jp/news/jnn_4863874_zen.shtml A French research institute says that the release of Cs-137 into the sea is 2.16 E16 Bq, or about 30 times larger than Tepco said at the end of April (940 E12 Bq). [ http://www.irsn.fr/FR/Actualites_pr...ident_Fukushima_sur_milieu_marin_26102011.pdf in French ]

http://sankei.jp.msn.com/affairs/news/111021/dst11102117120014-n1.htm (21 October) According to Tepco, the 250 mSv/h at the 5th floor of unit 2 is probably caused by deposits on floor and walls of radioactive gasses leaked from the PCV when the reactor was hot. The peeling off of the paint on the fuel handling crane was probably caused by steam.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111029/0820_cover.html Unit 1's cover structure is now completed with its radioactive substance removing system that uses filters and could remove 90% of radiations during tests.

 

[etudiant]

http://www.aec.go.jp/jicst/NC/tyoki/sakutei/siryo/sochi5/index.htm List of the documents that were distributed during the 5th meeting of the middle and long term committee that was held on 28 October. http://sankei.jp.msn.com/affairs/news/111021/dst11102117120014-n1.htm (21 October) According to Tepco, the 250 mSv/h at the 5th floor of unit 2 is probably caused by deposits on floor and walls of radioactive gasses leaked from the PCV when the reactor was hot. The peeling off of the paint on the fuel handling crane was probably caused by steam.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111029/0820_cover.html Unit 1's cover structure is now completed with its radioactive substance removing system that uses filters and could remove 90% of radiations during tests.

Tsutsuji-san, your work is the only comprehensive and careful monitoring site for the developments in this accident that I know of. No sensationalism, no preaching, just the facts. We are in your debt.

As a follow up to your last two items, it is reported that TEPCO is doubling the water injection into reactor 1 to about 8 tons/hr in conjunction with the completion of the cover structure. Presumably this increased flow plus the internal filtering are to prevent radioactive steam from contaminating the now closed off structure.
The problem is that afaik, reactor 1 is still generating well in excess of a megawatt of decay heat. That is enough in an hour to heat all 8 tons of water by 100 degrees centigrade and to boil off some of it in addition. So there will be substantial volume of radioactive steam generated inside the enclosure. TEPCO must control the flow of that steam very completely, else the enclosure becomes an instrument of contamination of all of reactor 1, mirroring the experience of the 5th floor of reactor 2.
Presumably TEPCO could curtail the steam generation with much more extensive water injection, but as the latest JAIF status report shows the water treatment facility running at about 40% capacity, TEPCO may not be able to inject more water because there is no place to store or process any more.
The impression is that while TEPCO has a grip on the situation, the margins remain pretty tenuous.

 

[nakos]

Dear members of this forum!
I have just registered here and didnt follow all 700+ pages of this discussion. Howerver, i participate actively on russian analog of this topic on site atominfo.ru which now is about to turn 600+ pages. I would like to ask someone here to give me brief summary on what you think on few questions that caused controversy among us in Russia:
1. hydrogen flow path from PCV into confinements: leakage? Vented into reactor hall on purpose? Backflow? Commonalities in units 1-2-3?
2. hydrogen flow unit 4: TEPCO explanations credible?
3. what is your intuition on conditions of RPVs? Total lower plenum breach or "leakage" only?
4. Where did Unit 2 blow up? S/C?
5. Unit 1 IC failure mode?
6. Units 2,3 RCIC failure mode: S/C saturation?
7. SFP fuel damage? Any at all?
8. Very specific question on hardened vent in Unit 1.
Here is diagram:

Is it possible to tell if MO210 valve is normally open or closed? Other valves? Purpose of rupture disc if we decide valve is in closed position?
More questions coming. Thank you all.

 

[rmattila]

Dear members of this forum!
I have just registered here and didnt follow all 700+ pages of this discussion. Howerver, i participate actively on russian analog of this topic on site atominfo.ru which now is about to turn 600+ pages. I would like to ask someone here to give me brief summary on what you think on few questions that caused controversy among us in Russia:
1. hydrogen flow path from PCV into confinements: leakage? Vented into reactor hall on purpose? Backflow? Commonalities in units 1-2-3?
2. hydrogen flow unit 4: TEPCO explanations credible?
3. what is your intuition on conditions of RPVs? Total lower plenum breach or "leakage" only?
4. Where did Unit 2 blow up? S/C?
5. Unit 1 IC failure mode?
6. Units 2,3 RCIC failure mode: S/C saturation?
7. SFP fuel damage? Any at all?
8. Very specific question on hardened vent in Unit 1.
Is it possible to tell if MO210 valve is normally open or closed? Other valves? Purpose of rupture disc if we decide valve is in closed position?
More questions coming. Thank you all.

My ideas: partly guesses, partly on more solid ground:

1. Leakage past containment lid seals is probably one route, since it has been reported on several occasions that they tend to leak even during regular containment pressure testing (around 5 bar), and during the accident, the PCV pressures exceeded 8 bar.

2. I would not say it's impossible, and the higher contamination on the outside of the SGTS filters as compared to the inside filters seems to support this idea.

3. Main circulation pump seals are probably leaking at all units. In addition to that, Unit 1 appears having depressurised during the late evening of March 11, which possibly indicates a leak from the bottom of the RPV. Boiling water reactor bottom plenum is not expected to completely breach even in severe accidents - it is more probable that some instrumentation tubes and/or control rod penetrations fail first and let the corium flow out. Other units than 1 - hard to say, since in my opinion we don't even have a good idea of the extent of the core damages.

5. According to the TEPCO report to the IAEA, it appears that the unit 1 IC did not fail at all: it just was not used. At 15:03 on March 11, they closed the IC valve and at 15:07 activated the HPCI; after the tsunami the HPCI failed, but the IC was not reactivated. Around 18:18-18:25 they briefly opened the IC valve, but closed it again for another 3 hours. Around 18:30 there would probably have been so much hydrogen in the reactor, that the steam was not able to enter the IC any more. In the recent video it was shown how the water gauges at the IC:s show the tanks still to be 70 % full.

6. A plausible explanation, although I have not been able to get verification.

7. The results given in April on the unit 4 pool water samples indicate very limited (if any) damage to unit 4:s spent fuel. At Unit 3, there probably are failures in the pool due either the hydrogen explosion or the subsequent uncovery.

8. According to the TEPCO reports to the IAEA, the MO210 valve seems to be normally closed and has to be opened as part of preparations for venting. All in all, it seems a very complicated procedure, with DC current needed for the said valve, compressed air for the other valve, and the containment pressure must be high enough to break the rupture disc. My uneducated guess is, that since there's no scrubbing or filtration in the pressure relief line, they have tried to make spurious initiation of the venting improbable by providing the multiple obstacles. Which turned out catastrophical, since the failure to vent the containments in the severe accident conditions delayed the capability to pump in firefighting water and most probably made the core damages much worse than they would have been if the pressure reduction would have taken place sooner. (Another contributing factor seems to have been the design of the reactor pressure relief lines, which also require both DC current and compressed air to function, and the delay to relieve reactor pressure after the failure of the RCIC/HPCI systems seems in my opinion to have been the most significant single factor contributing to the core damages at units 2 and 3.)

I am no expert in GE BWRs (consider myself somewhat of an expert on the ASEA line of BWRs, however), and have followed the events from the other side of the globe mainly through NHK, TEPCO's reports and the wonderful contributions of Tsutsuji-san, so the answers above are not to be taken as anything more than just my personal impressions based on the data I've been able to get.

 

[zapperzero]

1. hydrogen flow path from PCV into confinements: leakage? Vented into reactor hall on purpose? Backflow? Commonalities in units 1-2-3?
2. hydrogen flow unit 4: TEPCO explanations credible?
3. what is your intuition on conditions of RPVs? Total lower plenum breach or "leakage" only?
4. Where did Unit 2 blow up? S/C?
5. Unit 1 IC failure mode?
6. Units 2,3 RCIC failure mode: S/C saturation?
7. SFP fuel damage? Any at all?
8. Very specific question on hardened vent in Unit 1.
Purpose of rupture disc if we decide valve is in closed position?

Hello neighbor! While there is no consensus yet, I will attempt to summarize and others will undoubtedly correct me.
Here goes:

1. leakage, in all cases (units 1, 2 3).
2. disputed. the other theory is hydrogen produced via radiolysis of the (hot) water of the #4 SFP.
3. disputed. possibility of no RPV bottom head breaches is still being taken into consideration, at least by some.
4. S/C breach is supposed to have occurred
5. operator error or equipment failure. IC was not used to capacity.
6. apparently they did not fail, per se
https://www.physicsforums.com/showpost.php?p=3419527&postcount=10696
7. unknown, presumed to be limited
8. Vent path is supposed to be closed in normal operation. The idea is to open the valve, then wait for the pressure disk to blow when pressure reaches its preset limit.

 

[ppaavola]

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111015_04-e.pdf Infrared pictures of top parts of unit 1 and unit 3

The markings in these new IR-pictures - and also the shape of the largest hotspot (or rather "hotline") in the unit 1 -picture - seem to resolve the question about the shapes of the reactor well shield plugs used in Fukushima Daichi units. Apparently the japanese didn't like the idea of full semicircles - but instead wanted to divide the circular lids into three sections.

Another note - or rather question: What might be those hot rodlike objects just outside the Unit 3:s SPF:s NW corner? As a layman (who has only just recently found this forum) i dare not say, what I personally suspect...

 

[MadderDoc]

<..>What might be those hot rodlike objects just outside the Unit 3:s SPF:s NW corner? As a layman (who has only just recently found this forum) i dare not say, what I personally suspect...

Well, they caught my eye too :-) After considering the weather at the time and date of the recording, as displayed by the webcam, and conferring with VIS photos, I think they most likely are some parts of corrugated iron from the roof covering that have come to lie there on top of everything else, and oriented such that they are being heated by the morning sun.

 

[jim hardy]

"and oriented such that they are being heated by the morning sun."

looks like they're 80-90F in a 65-ish ambient? sounds reasonable for warming in the sun.

IR cameras are sensitive to emissivity of a surface , so might be strips of galvanized sheet lying on rubble.

but there's been lots of peculiar shapes in the photos over these months and many of us are watching and wondering, like you.

 

[shadowncs]

What might be those hot rodlike objects just outside the Unit 3:s SPF:s NW corner?

I too would guess they are just some steel girders from all the mess that
- were modestly heated up by the underlying SFP steam
- were modestly heated up by the morning sun (assuming time on photo is in Japan timezone)

The difference is 10 deg Celsius, IR camera is calibrated on quite a sensitive scale. For comparison, if we were to take those er.. rods and put them in the blueish area (removing SFP heat which has a T of about 24 Celsius relative to the 18 Celsius of other structure) they would probably glow dark yellow or light orange (28 C) in that pic.

I think if those were fuel rods the gamma emissions would be noticeable, including to the ground by gamma backscatter and we would have seen a huge robot-based effort to remove them, which didn't happen AFAIK.

 

[MadderDoc]

<..>
I think if those were fuel rods the gamma emissions would be noticeable, including to the ground by gamma backscatter and we would have seen a huge robot-based effort to remove them, which didn't happen AFAIK.

Also, if hot fuel assemblies were lying there now, scattered off the NW corner of the SFP. they should've lit up on the roof ever since the explosive events on March 14th, but there is no heat signature apparent in that spot in any of the early thermographs from March and April.

 

[zapperzero]

People. Please, please for the love of Shub-Niggurath stop with the fuel rods thing.

Here's all the testing you need, to find out if used fuel rods are out in the open:

Are low-flying birds dropping dead out of the sky? (Y/N).

 

[tsutsuji]

http://www.nikkansports.com/general/news/f-gn-tp0-20111031-857148.html It was found that two rest stations, because they are located outside of the plant premises close to the western entrance gate, are not included in the radiation management area, while the radiation there is about 2 ~ 16 μSv/h. It is required by law to include into the management area all the areas where an accumulated dose of 1.3 mSv is exceeded in 3 months.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111030/0435_2gouki.html The PCV gas extraction system was started on 28 October at unit 2.

 

[zapperzero]

http://www.nikkansports.com/general/news/f-gn-tp0-20111031-857148.html It was found that two rest stations, because they are located outside of the plant premises close to the western entrance gate, are not included in the radiation monitoring area, while the radiation there is about 2 ~ 16 μSv/h. It is required by law to include into the monitoring area all the areas where an accumulated dose of 1.3 mSv is exceeded in 3 months.

This.

let's itemize:
1. workers STILL don't have personal dosimeters
2. the areas were not checked by a health physicist, radiation safety engineer or generally anyone with a counter prior to being designated "rest stations"
3. there is no radiation map of the entirety of the work-site. Only of the immediate environs of the NPP itself
4. monitoring is absent from areas not known to be already contaminated

Therefore, external dose estimates provided by TEPCO are based on hopium.

 

[ppaavola]

As finnish SAM -solutions for TVO:s two ASEA-BWR:s have been discussed (also) in this forum, some may find this just released report interesting: http://www.tvo.fi/uploads/File/2011/EU-stresstest_TVO_public_final.pdf

 

[BC1]

Hello all. Long time lurker, first time poster, ETC.

I have been waiting with great interest to see Marco Kaltofen from WPI's presentation on environmental radioactivity in Japan and the US from the Fukushima disaster. This came out yesterday - http://www.fairewinds.com/content/marco-kaltofen-presentation-apha .

I have not seen the raw data, and if anyone has, a link would be great. But a couple things strike me as odd right away - first, that he reports detection of Cs-134 and Cs-137 in US soil only in two isolated locations (page 19). That seems very odd, since there's Cs-137 nearly everywhere from pre 3/11, and also there had been Cs-134 found in nearly every sample that the UC Berkeley team has tested. The second thing is that his abstract stated that an isolated soil sample in the US came back at 8nCi/kg of combined cesium activity - http://fukushimaupdate.com/radiation-exposure-to-the-population-in-japan-after-the-earthquake/. 8nCi/kg is much higher than what anyone else has reported.

Thoughts anyone?

 

[NUCENG]

Hello all. Long time lurker, first time poster, ETC.

I have been waiting with great interest to see Marco Kaltofen from WPI's presentation on environmental radioactivity in Japan and the US from the Fukushima disaster. This came out yesterday - http://www.fairewinds.com/content/marco-kaltofen-presentation-apha .

I have not seen the raw data, and if anyone has, a link would be great. But a couple things strike me as odd right away - first, that he reports detection of Cs-134 and Cs-137 in US soil only in two isolated locations (page 19). That seems very odd, since there's Cs-137 nearly everywhere from pre 3/11, and also there had been Cs-134 found in nearly every sample that the UC Berkeley team has tested. The second thing is that his abstract stated that an isolated soil sample in the US came back at 8nCi/kg of combined cesium activity - http://fukushimaupdate.com/radiation-exposure-to-the-population-in-japan-after-the-earthquake/. 8nCi/kg is much higher than what anyone else has reported.

Thoughts anyone?

If I were waiting to see this presentation I would have been disappointed. I have judged high school science and engineering fair entries that had better focus and provided more cogent hypotheses to analysis to conclusion. The conclusion he draws in the last slide is not a logical result of the information he presents, but it was probably what motivated Fairewinds to post it. He presented a result of testing automobile air filters by contact on photographic or xray plates which is interesting, but withoiut quantification is pretty worthless.

Do yourself a favor and take the time to read through this thresd. You will find much more in depth discussion and analysis here than Arnie Gundersen provides at Fairewinds. If you take time to read back through this thread you will find most of the information was here already, so you really didn't need to wait.

 

[NUCENG]

This.

let's itemize:
1. workers STILL don't have personal dosimeters
2. the areas were not checked by a health physicist, radiation safety engineer or generally anyone with a counter prior to being designated "rest stations"
3. there is no radiation map of the entirety of the work-site. Only of the immediate environs of the NPP itself
4. monitoring is absent from areas not known to be already contaminated

Therefore, external dose estimates provided by TEPCO are based on hopium.

ZZ, did you translate the article provided by Tsutsuji to draw those conclusions, or is that the pesimistic opinion of the zapperzero we've come to know and love here? I saw nothing in the article that indicated a shortage of dosimeters. I saw nothing that indicated any worker exceeded dose limits because of the mistake. The article reported that TEPCO admitted the mistake and "poor management." Obviously they found the problem so they were monitoring the rest areas, even if it was later than the law required.

During the Great Depression American humorist Will Rogers said he never wrote a joke, he just read the newspapers and repeated the facts. We can all take that as a hint. There is so much fact about Fukushima to criticize we don't need to stretch this stuff so far. Maybe a dose of hopium would balance us all.

 

[BC1]

If I were waiting to see this presentation I would have been disappointed. I have judged high school science and engineering fair entries that had better focus and provided more cogent hypotheses to analysis to conclusion. The conclusion he draws in the last slide is not a logical result of the information he presents, but it was probably what motivated Fairewinds to post it. He presented a result of testing automobile air filters by contact on photographic or xray plates which is interesting, but withoiut quantification is pretty worthless.

Do yourself a favor and take the time to read through this thresd. You will find much more in depth discussion and analysis here than Arnie Gundersen provides at Fairewinds. If you take time to read back through this thread you will find most of the information was here already, so you really didn't need to wait.

Nuceng - Yes, I have to admit that I was dissapointed too. I expected more, mostly because this guy has done some great work. Google his name - it seems to me that his work on finding tiny amounts of plutonium etc. in dusts is pretty much in a league of its own.

I have read most of the info here on PF, and appreciate it very much, no tinfoil here.

 

[tsutsuji]

http://www.asahi.com/national/update/1102/TKY201111020003.html (2 November 05:02 AM) "Fukushima Daiichi unit 2 - Possibility of nuclear fission - Borated water injection". Short-lived Xenon was detected at unit 2. Tepco started injecting borated water at 02:50 AM on 2 November. No change was observed at monitoring posts inside plant premises.

http://www3.nhk.or.jp/news/html/20111102/t10013667531000.html (2 November 06:38 AM) Xe-133 and Xe-135 (U-235 fission products) were detected on 1 November on the measuring instruments installed near the exit of unit 2's PCV gas extraction system. As nuclear fission cannot be ruled out, Tepco started injecting borated water shortly before 03:00 AM. Reactor pressure and temperature, plant site monitoring posts are stable. Even if nuclear fission is occurring it must a small scale reaction.

 

[Jim Lagerfeld]

http://www.asahi.com/national/update/1102/TKY201111020003.html (2 November 05:02 AM) "Fukushima Daiichi unit 2 - Possibility of nuclear fission - Borated water injection". Short-lived Xenon was detected at unit 2. Tepco started injecting borated water at 02:50 AM on 2 November. No change was observed at monitoring posts inside plant premises.

http://www3.nhk.or.jp/news/html/20111102/t10013667531000.html (2 November 06:38 AM) Xe-133 and Xe-135 (U-235 fission products) were detected on 1 November on the measuring instruments installed near the exit of unit 2's PCV gas extraction system. As nuclear fission cannot be ruled out, Tepco started injecting borated water shortly before 03:00 AM. Reactor pressure and temperature, plant site monitoring posts are stable. Even if nuclear fission is occurring it must a small scale reaction.

Thank you for the quick linking! Reading both articles, it is still not clear to me whether the installation of the gas management system allowed the measurement of the fission products, revealing a process which might have been already continuing for some time, or whether the xenon is a totally new development. Is it clearer to you?

 

[rowmag]

Looks like from the second article that the gas filtering and measurement system was only started on 10/28, and this was the first measurement result from that. So this may have been going on all along.

Could this provide a source term for those transient mini-spikes seen throughout the Kanto area when it is raining and the wind is coming from the power plant? (Still waiting to see an example of such a spike when the wind is not coming from Fukushima Daiichi.)