Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[zapperzero]

Have you guys seen this?

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121015_01-e.pdf

One of the pictures shows what appears to be part of an empty rack.

 

[Cire]

So they are meant to keep the inflow?

You want just enough inflow so you know contaminants are not flowing out. But not so much inflow that your pumps can't keep up.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121017/index.html On 17 October, the NRA launched a new "Special Nuclear Facility Monitoring and Assessment Committee" composed of nuclear safety experts including Fukushima prefecture related persons, whose purpose is to continuously monitor Fukushima Daiichi's decommissioning.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121016/index.html The Nuclear Regulation Agency [an administrative body below the NRA] launched its bureau located in Fukushima prefecture Hirono town, where they borrow a soccer-related facility. It shall deal with Daiichi's decommissioning (8 people) and also the Fukushima Daini nuclear power plant (6 people).

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121016/1725_hairo.html The Chiba Institute of Technology - which developed Quince - has presented a new robot, called "Sakura", designed for Fukushima Daiichi. With a 50 cm height it is about 2/3 of the size of the older generation. As replacing the batteries of a contaminated robot takes too much time, it is rechargeable. The Institute said they would like to have it start being used at Fukushima Daiichi by the end of this year.

http://www.nedo.go.jp/news/press/AA5_100156.html Sakura related press release. The other item, called HAL, is a robot suit with a radiation shield, a cooling system, and a biological data monitoring system (such as body temperature, heart pulsation) (for human beings to carry) (for nuclear disasters in general, not specifically for Fukushima Daiichi).

 

[Cire]

Some good reading:

http://www.new.ans.org/pubs/journals/nt/a_14634

Summary and opinion: http://atomicinsights.com/2012/10/oak-ridge-researchers-prove-fukushima-unit-4-spent-fuel-pool-never-a-danger.html#more-13073

 

[etudiant]

The paper mentioned here: http://www.new.ans.org/pubs/journals/nt/a_14634
is unfortunately behind a paywall, but the second reference from Atomic Insights does provide the meat of the paper.
The paper shows quite clearly that left entirely to itself, the Reactor 4 SPF and its contents would have reached equilibrium around 90*C, well below the boiling point, with enough water present to keep the fuel covered for at least 13 days.
So NRC Chairman Jaczko's comments to the contrary were wrong.
In Jaczko's defense, there had been a big quake and several explosions, suggesting leaks were possible, plus the Reagan had encountered a massive nuclear plume, so that SPF was a reasonable source of concern.
What is surprising is that with three reactors having had explosions, the NRC heads concern should focus on the SPF of the only reactor left unfuelled at the time of the accident.

 

[zapperzero]

What is surprising is that with three reactors having had explosions, the NRC heads concern should focus on the SPF of the only reactor left unfuelled at the time of the accident.

I seem to remember the #4 SFP was making the most heat, as it contains the most recently-extracted fuel, but I may be wrong.

 

[Rive]

The paper shows quite clearly that left entirely to itself, the Reactor 4 SPF and its contents would have reached equilibrium around 90*C, well below the boiling point, with enough water present to keep the fuel covered for at least 13 days.

Without knowing the whole paper and the used models I cannot be sure, but if the equilibrium of the pool was around 90*C, then for me it definitely suggest that around some hot fuel bundles there was boiling.

90 -> 100*C temperature change with natural convection means a very limited cooling.

I have some serious doubts.

 

[Hiddencamper]

Without knowing the whole paper and the used models I cannot be sure, but if the equilibrium of the pool was around 90*C, then for me it definitely suggest that around some hot fuel bundles there was boiling.

90 -> 100*C temperature change with natural convection means a very limited cooling.

I have some serious doubts.

In the US, we assume boiling begins at 200F, or about 93C. I agree that 90C suggests localized boiling was happening as 90C was probably a bulk temperature and not localized, and as we know (and can be seen in PWRs), localized boiling can happen in various amounts as you approach boiling points.

Now I do know that it takes a few days for boiling to start in a normal SFP, additionally unit 4 had a much large water inventory to work with because the separator gate was out and the reactor was opened up. 13 days before full boiloff is possible, but some more specific data would be needed. Its likely boiling started within 4-5 days (full core decay heat load at 90 days since reactor shutdown for that mass of water).

I do know that spent fuel pools with a 1/3rd core offload (on their own) will BEGIN boiling in <72 hours, but the time to complete the boiloff takes longer than the time to start boil off (due to latent energy of water).

 

[tsutsuji]

Without knowing the whole paper and the used models I cannot be sure, but if the equilibrium of the pool was around 90*C, then for me it definitely suggest that around some hot fuel bundles there was boiling.

90 -> 100*C temperature change with natural convection means a very limited cooling.

I have some serious doubts.

If the mean temperature value is 90°C and if some parts are reaching 100°C, it means that other parts are lower than 90°C. Then, those colder parts would generate less steam. Are you sure that all in all the steam quantities are much different than when you use the simple model where all parts have the same temperature ?

Also, wouldn't the steam bubbles generated in the hot spot condensate before reaching the pool's surface ?

 

[Cire]

Don't forget that the pressure at the fuel bundles isn't atmospheric due to their depth. The boiling temperature is going to be a few degrees higher at that location. There will also be fairly significant thermals moving through the bundles.

 

[jmelson]

I seem to remember the #4 SFP was making the most heat, as it contains the most recently-extracted fuel, but I may be wrong.

I believe this is correct, fuel from the #4 reactor had been removed and placed in the
pool a couple months (?) before the earthquake, to prepare for major work in the reactor
vessel before refueling. Also, the pool was loaded with the fresh fuel to go in after the
work was complete.

Jon

 

[etudiant]

Without having seen the actual paper, the summary suggested that the SPF water temperature would rise over a period, but that the equilibrium for heat loss from evaporation versus decay heat from the stored fuel was slightly below 90*C, 87*C by the researcher's etimates.
That overall thermal balance would of course include hot spots around the more recently used fuel, so localized boiling with subsequent quenching of the steam bubbles would be a reasonable expectation.

 

[rmattila]

While the difference between 90 and 100 Celsius probably does not have a significant effect on the fuel cooling conditions, it may have an important effect on the fuel pool liner stresses. I don't know if the Fukushima pools were rated for 100 C, but I know that there are pools in some (European) plants dimensioned to withstand with certainty only about 85 C.

 

[Burnsys]

Is this report true?

http://www.agoracosmopolitan.com/news/nature/2012/10/19/4621.html

Mitsuhei Murata, who served his country as Ambassador to both Senegal and Switzerland, explained in a recent interview that far from the situation at the Fukushima Daiitsu plant improving, it is actually worsening in an alarming way: the ground beneath the plant's number 4 reactor is sinking. Mr Murata implied that the whole structure is on the verge of collapse. He wrote to the Secretary General of the United Nations stating unequivocally that the fate, not only of Japan, but of the rest of the world depends on the No. 4 reactor.

 

[tsutsuji]

http://www.iaea.org/newscenter/focus/fukushima/statusreport280912.pdf Fukushima Daiichi Status Report, 28 September 2012 (A summary of the latest information provided by Tepco)

Is this report true?

http://www.agoracosmopolitan.com/news/nature/2012/10/19/4621.html

Mitsuhei Murata, who served his country as Ambassador to both Senegal and Switzerland, explained in a recent interview that far from the situation at the Fukushima Daiitsu plant improving, it is actually worsening in an alarming way: the ground beneath the plant's number 4 reactor is sinking. Mr Murata implied that the whole structure is on the verge of collapse. He wrote to the Secretary General of the United Nations stating unequivocally that the fate, not only of Japan, but of the rest of the world depends on the No. 4 reactor.

One of Tepco's replies to such fears is available at http://www.tepco.co.jp/en/nu/fukushima-np/info/12062901-e.html (29 June 2012)

See also the following:

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120831/0450_4gouki.html Tepco has completed a new report on unit 4's earthquake resistance, taking into account the most recent findings on wall bulge etc. and the fact that as a consequence of removing the debris on the upper floors, the mass of the building was reduced by 4700 tons. The conclusion is the same as in the May 2011 report: the building can withstand [Japan Meteorological Agency] intensity 6 earthquakes.

http://www.tepco.co.jp/en/press/corp-com/release/2012/1217413_1870.html The new seismic safety report

Also, that the whole Fukushima coast sunk by some 60 cm (and moved by 2.4 m Eastwards) during the 11 March 2011 earthquake is not the same as saying that unit 4 or anything else is still sinking now.

http://en.wikipedia.org/wiki/2011_earthquake_and_tsunami#Geophysical_effects "A 400 km (250 mi) stretch of coastline dropped vertically by 0.6 m (2.0 ft), allowing the tsunami to travel farther and faster onto land"

See also http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120413_04-e.pdf "Water level measurement in order to confirm the soundness of the Unit 4 Reactor Building" (13 April 2012)

 

[ronaldkr]

The paper mentioned here: http://www.new.ans.org/pubs/journals/nt/a_14634
is unfortunately behind a paywall, but the second reference from Atomic Insights does provide the meat of the paper.
The paper shows quite clearly that left entirely to itself, the Reactor 4 SPF and its contents would have reached equilibrium around 90*C, well below the boiling point, with enough water present to keep the fuel covered for at least 13 days.
So NRC Chairman Jaczko's comments to the contrary were wrong.
...
What is surprising is that with three reactors having had explosions, the NRC heads concern should focus on the SPF of the only reactor left unfuelled at the time of the accident.

Dear etudiant,
you are falling for a part of the never-ending witchhunt against chairman Jaczko. The problem at that time was not evaporation of the SFP at unit 4; they did not know if it lost water. Remember the helicopter overflights for refilling (a show by the Japanese SDF for sure)? The first attempt was canceled because of high radiation dose. The second attempt was done with a lead plate under the chopper.

Now, how much water was in the pool that the government-ordered show flight was abandoned? And why did they order a large concrete pump after getting the radiation readings?

Of course, we all know that fission boilers with SFPs on the top level are totally safe -- so it cannot be, and must not be that a pool loses water. Jaczko had concerns and even dared to voice them.

 

[etudiant]

Dear etudiant,
you are falling for a part of the never-ending witchhunt against chairman Jaczko. The problem at that time was not evaporation of the SFP at unit 4; they did not know if it lost water. Remember the helicopter overflights for refilling (a show by the Japanese SDF for sure)? The first attempt was canceled because of high radiation dose. The second attempt was done with a lead plate under the chopper.

Now, how much water was in the pool that the government-ordered show flight was abandoned? And why did they order a large concrete pump after getting the radiation readings?

Of course, we all know that fission boilers with SFPs on the top level are totally safe -- so it cannot be, and must not be that a pool loses water. Jaczko had concerns and even dared to voice them.

I have no problems with his statement. He could have been right in the event of SPF damage from the quake, which does not seem impossible given the quake shifted the entire region by several feet and dropped the land by a couple of feet, as Tsutsuji-san notes above.
He specifically did note a potentially catastrophic risk if the SPF 4 were low on water. He apparently believed that was the case, based on an incorrect work flow document from TEPCO that did not make clear that both RPV and SPF were filled with water to the top for the fuel removal. So he was mistaken, but understandably so.
That said, your idea that merely noting the mistake is to join in a witch hunt against Chairman Jaczko seems a little overprotective.

 

[Hiddencamper]

I have no problems with his statement. He could have been right in the event of SPF damage from the quake, which does not seem impossible given the quake shifted the entire region by several feet and dropped the land by a couple of feet, as Tsutsuji-san notes above.
He specifically did note a potentially catastrophic risk if the SPF 4 were low on water. He apparently believed that was the case, based on an incorrect work flow document from TEPCO that did not make clear that both RPV and SPF were filled with water to the top for the fuel removal. So he was mistaken, but understandably so.
That said, your idea that merely noting the mistake is to join in a witch hunt against Chairman Jaczko seems a little overprotective.

Just to add a little bit to the water level, for US nuclear plants the technical specifications change greatly if the RPV and SPF are filled at least 22 feet above TAF, as the total inventory of water requires many days prior to a critical situation with regards to fuel cooling. Above 22 feet less ECCS pumps and emergency power systems are required to be in effect, and alternate decay heat removal systems can be used in place of normal removal systems. Additionally secondary containment is allowed to be breached provided OPDRVs or fuel moves arent in effect (Operations with Potential for Draining the Reactor Vessel)

 

[tsutsuji]

http://www.iaea.org/newscenter/focus/fukushima/statusreport280912.pdf Fukushima Daiichi Status Report, 28 September 2012 (A summary of the latest information provided by Tepco)

is linking to :

http://www.nsr.go.jp/archive/nisa/english/files/Sideevent_handout.html Side Event by Government of Japan at 56th IAEA General Conference, Sep 17, 2012 Briefing on TEPCO's Fukushima Dai-ichi NPS accident

including:

http://www.nsr.go.jp/archive/nisa/english/files/P-4.pdf Harutaka Hoshi and Masashi Hirano, Japan Nuclear Energy Safety Organization (JNES): Severe Accident Analyses of Fukushima-Daiichi Units 1 to 3

 

[Rive]

Are you sure that all in all the steam quantities are much different than when you use the simple model where all parts have the same temperature ?

I'm sure that seeing/assuming the boiling would made me scared in those times with so few direct information regarding the U4 pool. With only hot water, you can see how much heat is there, or at least you can give an upper limit: if it's boiling, then you can only assume.

As I see this part of the discussion has no real basis if we are about the 'who was right/wrong' track.

 

[tsutsuji]

The 11th mid & long term meeting was held on 22 October 2012: http://www.meti.go.jp/earthquake/nuclear/20121022_01.html

1) Previous related topics:

The 10th meeting (24 September 2012) https://www.physicsforums.com/showpost.php?p=4096335&postcount=13735

The 9th meeting (27 August 2012) https://www.physicsforums.com/showpost.php?p=4051034&postcount=13635

The 8th meeting (30 July 2012) https://www.physicsforums.com/showpost.php?p=4020743&postcount=13588

The 7th meeting (25 June 2012) https://www.physicsforums.com/showpost.php?p=3979794&postcount=13512

The 6th meeting (25 May 2012) : https://www.physicsforums.com/showpost.php?p=3933442&postcount=13399

The 5th meeting (23 April 2012) : https://www.physicsforums.com/showpost.php?p=3881074&postcount=12979

The 4th meeting (28 March 2012) : https://www.physicsforums.com/showpost.php?p=3838108&postcount=12764

The 3rd meeting (27 February 2012) was translated into English on Tepco's website : http://www.tepco.co.jp/en/nu/fukushima-np/roadmap/conference-e.html

2) Translation:

22 October 2012 government-Tokyo Electric mid and long term response committee, steering committee (11th meeting)

http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01a.pdf Agenda
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01b.pdf Participants

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01c.pdf Abstract of the proceedings of 10th steering committee meeting

Document 2: Plant status
Document 2-1: Plant status
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01d.pdf Plant parameters
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01e.pdf Accumulated water storage status

Document 3 Study and execution of each special plan

3-1 Cooling by closed loop water injection
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01f.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01g.pdf Unit 2 alternative thermometer installation
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01h.pdf Unit 1 PCV internal survey results
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01j.pdf Nitrogen injection into Unit 1 suppression chamber
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01k.pdf Completion of unit 4 SFP salt removal

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01m.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01n.pdf Responses toward the start of the multinuclide removal facility (ALPS)'s hot test

3-3 Countermeasures to reduce environmental radiations
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01p.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01q.pdf Mid and long term implementation policies for plant premises decontamination
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01r.pdf Radiation dose reduction in front of Fukushima Daiichi NPP's seismic-isolated building
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01s.pdf Results of evaluation of additional releases from reactor buildings

3-4 Improvement of working conditions
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01t.pdf Schedule

3-5 Countermeasures for spent fuels pools
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01u.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01v.pdf Debris removal work, reactor building top part, unit 3
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01w.pdf Debris removal work, reactor building top part, unit 4
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01x.pdf Plans to survey unit 1's operating floor again
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01y.pdf Results of preliminary underwater survey (survey No. 3) into unit 3 spent fuel pool for the purpose of inside pool debris removal

3-6 Preparations for fuel debris removal
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01z.pdf Schedule

3-7 Treatment and disposal of radioactive waste
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01aa.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01bb.pdf Debris, cut down trees management status
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01cc.pdf Cut down trees (branches, leaves, roots) temperature monitoring status
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01dd.pdf Installation of cut down tree temporary storage vessels

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_01ee.pdf roadmap progress (abstract)

22 October 2012 government-Tokyo Electric mid and long term response committee, technical development progress headquarters (10th meeting) ( http://www.meti.go.jp/earthquake/nuclear/20121022_02.html )

http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02a.pdf Agenda

http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02b.pdf Committee member list

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02c.pdf Abstract of proceedings of 9th meeting (draft)

Document 2
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02d.pdf Outline of progress status of grasping in-reactor status by upgrading accident progression analysis tools

Document 3
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02e.pdf Progress status of "development of management and disposal techniques for the secondary waste generated by contaminated water treatment" and ""development of management and disposal techniques radioactive waste"

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02f.pdf Outline of progress status of "building material accounting methods for fuel debris"

Document 5
http://www.meti.go.jp/earthquake/nuclear/pdf/121022/121022_02g.pdf Progress status of "development of criticality management techniques for fuel debris"

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121025/index.html On 24 October, Tepco inspected the top part of unit 1's reactor building using a balloon (diameter 2 m, height 3 m ). It was confirmed that although there are concrete debris, etc, the overhead crane and the fuel handling machine have not fallen. The radiation measured near the 2nd floor was 150 mSv/hour, and the one near the 5th floor was 85 mSv/hour. Tepco had tried to do this survey in August, but failed as the balloon hit some debris. This time they used a smaller diameter balloon, and were able to inspect the top part of the building for the first time.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121024_02-e.pdf Results of Reinvestigation of Unit 1 Operation Floor at Fukushima Daiichi Nuclear Power Station (24 October 2012)

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120808_02-e.pdf 8 August 2012 balloon mission

[question: would it not have been easier to install one camera or two on the top beams of the cover/tent structure ? Or to put cameras on the crane that was used to build the cover structure ? (http://photo.tepco.co.jp/en/date/2011/201110-e/111008-02e.html : Installation Work of Roof Panels for Reactor Building Covers at Unit 1, Oct 08, 2011)]

 

[westfield]

<snip>

[question: would it not have been easier to install one camera or two on the top beams of the cover/tent structure ? Or to put cameras on the crane that was used to build the cover structure ?

<snip>

TEPCO did attempt to get images of the U1 situation before they contructed the cover over Unit 1. There was some T-HAWK UAV imagery and some crane imagery.

However because the roof of Unit 1 collapsed somewhat like a blanket over the whole refuelling floor the view was limited from overhead.

Having said that, there was some earlier crane video that showed much of what has been obtained on this latest balloon effort. I can't find the clip on the TEPCO site but here is a link.

Video , U1, west side, FL5 Crane - Timestamped May 16 2011 (and yes, photobucket isn't very good for video :( )

Then there is this crane video from Oct 2011 which shows how limited the view was from above.
Situation[/PLAIN] of Upper Part of Unit 1 Reactor Building, Fukushima Daiichi Nuclear Power Station - Oct 08 2011

Also, thankyou again for your reports.

 

[zapperzero]

would it not have been easier to install one camera or two on the top beams of the cover/tent structure ?

they should have put in a light rolling bridge type crane and an airlock
hindsight is 20/20 I guess and TEPCO's self-enforced lack of curiosity is infinite

 

[Joffan]

would it not have been easier to install one camera or two on the top beams of the cover/tent structure ?

Indeed; even now, would it not be easier to instrument a replacement roof section with all sorts of sensors, including cameras, and then swap with one of the installed sections? Instead of messing about with balloons?

 

[tsutsuji]

It is Tepco's own idea. You can see green color cameras on the diagram on the last page at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110624e15.pdf

I wonder what happened to those cameras.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121030/index.html The investigation launched after the "pocket dosimeter in lead cover" problem revealed additional problems. Investigating the cases where both dosimeters [sounding like each worker always carries two of them?] had a difference higher than 25%, at least 20 cases of inappropriate radiation exposure management were revealed. They found 3 data input mistakes, 6 inappropriate management cases like the worker carries his dosimeter when he is off duty, and 11 cases where the lower of the two dosimeter values had been reported [sounding like the rule is to report the highest one]. However, no intentional misreporting was found. The ministry of labour and health instructed Tepco and 37 subcontractors to take recurrence prevention countermeasures.

 

[tsutsuji]

Asahi has a couple of stories in English:

Teleconference excerpts:

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201210140034 "A day wasted"
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201210140034?imgIX=0&page=2 "Have we got batteries?"
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201210140034?imgIX=0&page=3 "Radiation rises"
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201210140034?imgIX=0&page=4 "Yoshida overburdened"

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201211030052 "Tepco admits 4th worker exposed to radiation in early days of disaster"

NHK has a set of stories questioning whether Tepco can keep a sufficient workforce to perform the decommissioning:

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121105/2010_taiguu.html An increasing number of workers resign because remuneration is worsening. At the start, I received 230,000 per month, and just before I resigned, I had only 180,000 and had to pay for lunch, a worker who resigned says. Another one who came from Kansai had 250,000 that decreased to 200,000 and he was asked to leave the company-paid ryokan where he was staying.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121105/index.html It was found by journalist investigation/interviews that the number of registered workers is 8000 instead of the 24,000 figure presented by Tepco. At present, 3000 workers are working on a given day. Tepco estimates it needs 11,700 workers for this year. Tepco asserted that it can secure this number, based on the fact that 24,000 workers have registered. Actually this figure is the number of workers who registered since the accident. Since then, 16,000 have canceled their registration, and as of last month, only 8000 workers were registered.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121106/index.html Fukushima prefecture asked Tepco whether it can secure enough workforce. Tepco said "as the needed workforce per month is 6000, 8000 registered workers is enough".

 

[SteveElbows]

Dear etudiant,
you are falling for a part of the never-ending witchhunt against chairman Jaczko. The problem at that time was not evaporation of the SFP at unit 4; they did not know if it lost water.

Sorry for the delay in replying to this, I've not been here for a few weeks.

Part of the reason that US concerns about the fuel pool lagged behind the established reality is quite visible in the transcripts that were published a long time ago. Their man on the ground in Japan had formed an opinion of the situation, and as is often the case with humans he had trouble abandoning this position when contradictory facts started to emerge. He saw the state of the building and freaked out, and he was unconvinced by the first footage the Japanese obtained which they believed showed water in the pool. It didnt help that he was tired, and the Japanese refusal to give him a copy of footage to watch at his leisure probably made him suspicious.

Personally I think that as soon as the helicopter flight decided to dump water on reactor 3 pool rather than reactor 4 pool, we had clear signs of what the people with the best information at the time thought was the priority.

Given that people didnt instantly catch on to the idea that the reactor well was full of water and the pool gate may have failed, and that they hadnt figured out why reactor 4 building exploded, its not really surprising that the worst scenarios for reactor 4 pool seemed credible in the early days.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121117/index.html The NHK journalists tried to check again radiation doses. When they found something strange ("unnatural") in the radiation data from Fukushima Daini, 12 km South of the accidented plant, they asked Tepco for clarification, and the existence of until now undisclosed data was revealed. These undisclosed data cover a period from 15 March to 3 April 2011. They include the following March 16 data : the until then 20 microsievert/h radiation jumped to 80 microsievert/h at around 09:40 and 87.7 microsievert/h 10 minutes later. About one hour sooner, at around 8:30 white smoke had risen from the Fukushima Daiichi unit 3 reactor building, and the relationship between the smoke and the radiation peak at Fukushima Daini is being questioned. Kado Shinichiro of Tokyo University says: "For analysis, it is highly regrettable that unreleased data come out one year and 8 months after the accident. It is necessary to check the data, including the relationship between the peak and the white smoke at unit 3". Tepco says "we are investigating why the data were not released. We'll study a release of these data as the investigation progresses".

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_121114_01-j.pdf Tepco submitted to the NRA a change in the "mid-term safety principles"-based operational plan report. Unit 3's future cover structure is shown on diagrams.

 

[zapperzero]

it is highly regrettable

Understatement of the month. The worst thing about it is that we'd all be quite justified by now in going off the deep end and wondering "Ok, what else is TEPCO still conveniently failing to release? Gojira maybe? "

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121120/1755_date.html The data had been collected by hand, and they [including the unreleased ones?] had been reported to the government [NISA, I guess]. The released data were showing only every 10 minutes for one hour every three hours, instead of every 10 minutes. The missing data have been added on Tepco's website on 19 November 2012.

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_121119_02-j.pdf Tepco's explanation about the missing Fukushima Daini radiation data.

http://www.tepco.co.jp/en/nu/monitoring/11031602a.pdf English version for 16 March 2011 [the unreleased data are still missing : there is a gap between 09:00 and 11:10]

http://www.tepco.co.jp/cc/press/betu11_j/images/110316d.pdf Japanese version for 16 March 2011 [the new completed version, I guess] [including the 80.0 and 87.7 microsievert/h figures at 09:40 and 09:50, Monitoring post MP-4]

 

[ronaldkr]

...
Personally I think that as soon as the helicopter flight decided to dump water on reactor 3 pool rather than reactor 4 pool, we had clear signs of what the people with the best information at the time thought was the priority...

Well, I remember that the first helicopter flight was abandoned because of too high radiation exposure and subsequent flights were done with a lead plate mounted underneath. So they might well have thought that the problem was the "shine" of the unit 4 pool (i.e. more or less empty) and not the air-bound radiation from the emissions of unit 3 (and the others).

I wonder if we can get documentation for this. Wikipedia says, " Chinook helicopters were preparing to pour water on Unit 3, where white fumes rising from the building was believed to be water boiling away from the fuel rod cooling pond on the top floor of the reactor building, and on Unit 4 where the cooling pool was also short of water." But the two sources given are dead.

Probably somebody remembered that unit 4 was full of water and therefore less an imminent danger compared to the unit 3 pool, where they also did not know about water leaks.

 

[SteveElbows]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121120/1755_date.html The data had been collected by hand, and they [including the unreleased ones?] had been reported to the government [NISA, I guess]. The released data were showing only every 10 minutes for one hour every three hours, instead of every 10 minutes. The missing data have been added on Tepco's website on 19 November 2012.

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_121119_02-j.pdf Tepco's explanation about the missing Fukushima Daini radiation data.

http://www.tepco.co.jp/en/nu/monitoring/11031602a.pdf English version for 16 March 2011 [the unreleased data are still missing : there is a gap between 09:00 and 11:10]

http://www.tepco.co.jp/cc/press/betu11_j/images/110316d.pdf Japanese version for 16 March 2011 [the new completed version, I guess] [including the 80.0 and 87.7 microsievert/h figures at 09:40 and 09:50, Monitoring post MP-4]

Interesting stuff! The UK data has been updated now too.

Obviously when looking at this we have to take into account wind direction. I have started looking through data for the period after the 16th, to see if there are any other spikes which those articles don't mention.

Firstly I suggest looking at data for the 15th, because there are plenty of high readings at Daini then too, and the wind was blowing from the north during many initial hours of this period. It is a shame the data only starts on the 15th, we could really do with some values from 9PM on the 14th onwards to see how these values may have grown in the first place, eg in relation to events occurring at reactor 2, or even earlier for reactor 3.

http://www.tepco.co.jp/en/nu/monitoring/11031502a.pdf

Increases on March 21st which are quite notable from 8:10 to 8:30am

http://www.tepco.co.jp/en/nu/monitoring/11032116a.pdf

Increases on March 22nd peaking around 14:20.

http://www.tepco.co.jp/en/nu/monitoring/11032215a.pdf

There were a couple of other times values temporarily rose in March but they were less significant numbers so I haven't bothered to highlight them here.

 

[SteveElbows]

I've been looking back at some investigation reports that may not have been translated very quickly after they were first published. I was looking for details of interest to me that I don't remember being published in other reports we talked about here.

http://icanps.go.jp/eng/03IIfinal.pdf

Page 61, in talking about possible leakage paths, notes that steam was seen escaping from a region of the upper part of damaged reactor 1 building that could be the concrete plugs above the vessel head. Its nice to see this mentioned, as it was infuriating that we saw this kind of thing on early video footage but there was no comment about it at the time. Sadly I don't think they make the same comments about reactor 3.

Around that part of the document they also mention a manhole that is built into the containment vessel head.

Page 68, when looking at possible sources of ignition for the hydrogen in the reactor 1 building, they note that shortly before the explosion, there are logs which suggest that electric power had just been restored to the boric injection system.

Various parts of this report are also rather good at pointing out how wrong some of the data used by the accident models for assessing things like fuel melt & RPV damage might be.

Page 75, they talk about time period where containment damage at reactor 2 may have already started to happen. The period they mention is from 13:45 to 18:10.

 

[SteveElbows]

The attachments are fascinating too. I've just posted about some pages of particular interest to the reactor 2 thread. I haven't had time to read the stuff dealing with reactor 3 yet but here are a couple of highlights in regards reactor 1 and this document:

http://icanps.go.jp/eng/02Attachment1.pdf

Pages 53-56 looks at the MAAP & MELCOR analysis and frankly discusses a number of large problems with the analysis these models offered.

Pages 64-67 discusses radiation increases around 21:25 on March 14th and the possibility that this wasnt just down to reactor 2 or even reactor 3, but also further damage occurring at reactor 1.