Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

http://www.tepco.co.jp/en/press/corp-com/release/2012/1205638_1870.html Release of the Fukushima Nuclear Accidents Investigation Report (Japanese only for now)

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120620/index.html Tepco released its final report. It generalises saying "As preparations against nuclear accident were complacent, pratical thinking was not sufficient". But many questions such as the cause of the large radioactive substance releases or the consequences of the earthquake remain unanswered more than one year after.

The report is based on hearing 600 people, on onsite surveys and data analysis.

There is no big difference with the interim report as regards the accident's causes, and it concludes: "It is impossible not to say that retrospectively there was complacency as regards tsunami estimates, and the insufficiency of preparations to resist tsunamis is the fundamental cause".

The response to the accident is evaluated as being basically appropriate as the people onsite responded desperately in a situation that exceeded assumptions. About the operation of emergency cooling equipments that the cabinet investigation committee had criticized as being inappropriate, while recognizing that there are points where preparedness was insufficient, it merely argues in defense that "response was in fact difficult".

Then it concludes, "As preparations against nuclear accident were complacent, during the response they were unable to imagine what was really happening onsite, and practical thinking was not sufficient".

Concerning the interference of the government, instructions quite out of touch of the real situation onsite were directly or indirectly given, "the plant manager was only torn between conflicting demands, and it was not a way to improve accident containing results".

The report also includes concrete proposals for the future: to study accident management under the assumption that nearly all equipment functions are lost, to complete meltdown preventing countermeasures, about the chain of command during an emergency, and the way to release information to the population.

Nuclear engineering specialist, Mr Miyano of Tokyo university says the report "is not sufficiently analysing the problems in past countermeasures and regulations". "It is questionable whether the true nature of the accident can be approached with this report only. 'concretely what should be regretted, what should be changed ?' it is necessary to extract the lessons, but it is difficult for this to be done by the accident's main protagonist Tokyo Electric alone. The conclusions must be drawn by analysing from the eyes of a third party."

 

[MadderDoc]

I think I've finally figured out what those dark structures at the seaside of unit 2 and Unit 1 turbine buildings really are. :-( Darned to have been so daft, thinking about it I had boxed myself in the vain hope that it might have been something to do with basic ground work to stopping contamination of the ocean, but alas, it is likely not.

In all simpleness, I believe those dark structures have been the construction sites for the sections to cover the lower east part of Unit 3, towards its turbine building. Here seen in an image from late May 2012:

http://gyldengrisgaard.eu/fuku_docs/daiichi-12-0528-01-hr_detail.jpg

And here below is a marked up view to the putative construction site for those cover sections, detail from original photo taken on February 28th 2012:

http://gyldengrisgaard.eu/fuku_docs/120313_01_detail.jpg

 

[MadderDoc]

There is groundwater inflow and outflow in basements.

Yes, since water treatment started about a year ago, the volume of water Tepco is handling has roughly doubled, corresponding to a net accumulation of about 400 m³/day, and it is too much to believe that this net inflow figure represents _only_ inflow.

Just helping disposal of radionuclides dissolved in basement water by slowly diluting them into ocean via groundwater.

Proceeding in such manner is helpful reducing storage tank hassles.
Good old Tepco already did some necessary preparations.
For example, covering seabeds around Fukushima-1 with concrete.
This delays and dilutes groundwater-supported disposal by spreading over larger area.

To be honest, wouldn't be installing a water tight barrier too early just be a big mistake?

Now groundwater-supported disposal proper is not something that happens fast, if it were only that I suppose doing something effective about the problem might wait until 2014. But I think the case is that the ground we are talking about is a landfill, now turned a radioactive dump, and under the surface it is criss-crossed with trenches, pipes and ducts -- that the area on the whole is as designed to facilitate fast liquid discharge to the ocean, and not at all a slow leaching bed. In that situation, to let on that it can wait years to put a stop to it is just disgraceful.

 

[SteveElbows]

Not much left of the upper parts of reactor 4 building now. I believe what we may be seeing in this video is dust caused by the cutting away of remaining parts of upper north-west wall.

 

[tsutsuji]

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_120605_04-j.pdf At 20:03 on 4 June unit 4 SFP had an "airfin cooler panel alarm" ringing, and it was found that secondary circuit pump A had tripped with some traces of burning on the pump's terminal box. Pump B was started at 20:27. At 10:30 on 5 June, pump B was shut down in order to perform an inspection. As the pool temperature is expected to rise by 0.3 °C/hour, this is not considered as being a problem for pool temperature control.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120606/index.html Unit 4 SFP temperature reached 42°C at 5 PM on 6 June. As Tepco found a malfunction in the connecting part between motor and cable [that must be the terminal box] of the backup pump [that must be pump B] as well, they made repairs and restarted the pump after 6 PM, and the pool is being cooled again. Tepco explains: "as the pool is further cooled, the temperature might drop by 10°C in half or in one day".

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120608_02-e.pdf Pictures of the faulty pump cables.

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_120614_05-j.pdf This is about a new leak (0.5 to 1 cm above floor) in the Areva decontamination facility, which had been operated in closed loop since May 21.

This leak has been investigated: a water level meter was wrong.

http://www.tepco.co.jp/en/press/corp-com/release/2012/1205585_1870.html "The leaked water is assumed to have come from the coagulation-sedimentation equipment of the decontamination apparatus. As a result of site investigation on June 15, it is assumed that the leaking part is the interspace of the piping penetration hole on the top side of waste liquid strage tank. And also it is assumed that the water of the tank flowed out, since the water did not flow downstream by shutting down the flow regulating valve of downstream pipes due to instantaneous descent of the level meter of the tank and inflow from upper stream was continued. The integrity verification was conducted on the same day, and the problem was confirmed. The level meter has been decided to be fixed".

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_03-e.pdf "Investigation Result of the Water Leak from the Decontamination Apparatus" with pictures and diagrams giving details about the failed tank.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120626/index.html Tepco made additional measurements of unit 4's reactor building walls' tilt. Last month a tilt thought to have been caused by the bulge created by the hydrogen expolsion was found at the western wall with a measurement of a 3.3 cm tilt for 13 m of height, which was about half the limit set by the Building Standards Act. Now they found 4.6 cm for 13 m of height on the third floor on the western side. All tilts are within the limits of the Building Standards Act. Tokyo Electric says the pool is supported by other pillars, etc. that are different from the outer walls where tilting was found, and that as a result of seismic analysis, there is no seismic safety problem.

http://photo.tepco.co.jp/date/2012/201206-j/120625_02j.html pictures of the unit 4 wall measurements (Japanese version)
http://www.tepco.co.jp/cc/press/2012/1205832_1834.html press release about the new unit 4 wall measurements (Japanese version)
http://www.tepco.co.jp/cc/press/betu12_j/images/120625j0201.pdf press release attachment (Japanese version) (with diagrams, etc...) "Report dealing on a study about seismic safety taking into consideration local outer wall bulging at Fukushima Daiichi unit 4 reactor building"

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120626/index.html Tepco made additional measurements of unit 4's reactor building walls' tilt. Last month a tilt thought to have been caused by the bulge created by the hydrogen expolsion was found at the western wall with a measurement of a 3.3 cm tilt for 13 m of height, which was about half the limit set by the Building Standards Act. Now they found 4.6 cm for 13 m of height on the third floor on the western side. All tilts are within the limits of the Building Standards Act. Tokyo Electric says the pool is supported by other pillars, etc. that are different from the outer walls where tilting was found, and that as a result of seismic analysis, there is no seismic safety problem.

Any words on measuring error? Or was there actual change between one measurement and the next?

 

[zapperzero]

Not much left of the upper parts of reactor 4 building now. I believe what we may be seeing in this video is dust caused by the cutting away of remaining parts of upper north-west wall.

Quite so. I wonder if anything of that can be seen on the newly-shielded radiation counters at the site boundary.
EDIT: I stopped wondering and started looking
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/2012monitoring/f1_lgraph-e.gif
lo and behold, there is a slight uptick starting on 6/23 or thereabouts.

 

[Joffan]

Quite so. I wonder if anything of that can be seen on the newly-shielded radiation counters at the site boundary.
EDIT: I stopped wondering and started looking
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/2012monitoring/f1_lgraph-e.gif
lo and behold, there is a slight uptick starting on 6/23 or thereabouts.

I don't see the uptick, and I'm usually pretty good at spotting graphical subtleties. I wouldn't expect much because unit 4 wasn't very radioactive in the first place, and all (or almost all) the dust will be from concrete that hasn't seen the outside world since it was poured during construction.

 

[zapperzero]

I don't see the uptick.

Look again . The detector near the main building shows the most visible trend. You can also get the data in the tables (on the same page) and play with it. There might be another cause, of course, such as high winds.

 

[tsutsuji]

Any words on measuring error? Or was there actual change between one measurement and the next?

They are not measuring the same measurement points. The new measurement with the 46 mm horizontal difference is located on the 3rd floor, halfway between the rows R6 and R7, while the older measurement of "approx. 33 mm" for "West 2" in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120525_05-e.pdf 6/17, was located on the same floor but exactly on row R6.

There might be a small change of 1 mm between both measurements on west2/R6-3rd floor as the report now says 32 mm (instead of "approx. 33 mm").

I attach translations of the bottom of page 7/57 and of page 9/57 of http://www.tepco.co.jp/cc/press/betu12_j/images/120625j0201.pdf

page 7/57

page 9/57

 

[SteveElbows]

The camera zoomed in further when they did the next days cutting operation on east upper wall:



I'm more interested in how the painfully slow debris-removal is going at reactor 3, but cranes & stack tower tend to obscure the view of that, and we need a better resolution anyway.

 

[LabratSR]

Highest radiation found at Fukushima No.1 reactor

http://www3.nhk.or.jp/daily/english/20120628_01.html

 

[MadderDoc]

Highest radiation found at Fukushima No.1 reactor

http://www3.nhk.or.jp/daily/english/20120628_01.html

After all those months, with reams of stories told potentially elevating the information level of journalists and the lay public ...still to the NHK writer of http://www.gyldengrisgaard.eu/fuku_docs/nhk20120628_01.pdf -- inside or outside the reactor, a pressure vessel, a containment, or a suppression chamber -- are all just one porridge.

Even as regards the most interesting angle apparently to the writer -- the alleged record breaking radiation, there appears to be no memory of any previous potential record-holder (although in reporting of record breaking the dethroned party and the previous record traditionally get a mention). Has the measured >10,000 mSv/hr at the vent/SGTS pipe to the Unit1+2 exhaust stack last July been forgotten?

http://www.gyldengrisgaard.eu/fuku_docs/110805_1_detail.jpg​

 

[MadderDoc]

The camera zoomed in further when they did the next days cutting operation on east upper wall:



I'm more interested in how the painfully slow debris-removal is going at reactor 3, but cranes & stack tower tend to obscure the view of that, and we need a better resolution anyway.

Much of the unit3 debris removal has gone on at ground level, and around the building in a rather big radius -- the Unit 3 explosion was a very littering event indeed.

Comparing this June 18th 2012 photo, with this September 15th 2011 photo it can be seen that quite some progress has been made as regards getting close to the building proper as well as apparently establishing a foothold, a heavy duty elevated working platform at the east wall of the upper floors. I'd expect some of the equipment used currently at unit 4 will be relocated to unit 3 in time.

 

[Rive]

Highest radiation found at Fukushima No.1 reactor

http://www3.nhk.or.jp/daily/english/20120628_01.html

http://photo.tepco.co.jp/en/date/2012/201206-e/120627_01e.html
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120627_02-e.pdf

- Isn't that radiation a bit high compared to the water drawn from the T/B basement for decontamination?
- Why is the radiation decreases underwater?

 

[elektrownik]

- Why is the radiation decreases underwater?

The water blocks radiation so it is suggest that the radiation source is somewhere out of the water

 

[Rive]

The water blocks radiation so it is suggest that the radiation source is somewhere out of the water

As it was suggested elsewhere maybe it's the torus.

If the torus itself is watertight and the cooling water escapes where the torus connected to the DW then the water inside the torus might be there from the very first days -> much more heavily contaminated than the water drawn from the T/B basements.

 

[Tepconium-311]

The water blocks radiation so it is suggest that the radiation source is somewhere out of the water

Why then radiation increases strongly when approaching water?
Doesn't this indicate water surface emitting high radiation?

As it was suggested elsewhere maybe it's the torus.

If the torus itself is watertight and the cooling water escapes where the torus connected to the DW then the water inside the torus might be there from the very first days -> much more heavily contaminated than the water drawn from the T/B basements.

Sadly shielding obstacles like walking girders aren't shown in Tepco presentation chapter 3 to help explain radiation measurements. They are only indicated in chapter 2.
If torus is watertight, wouldn't radiation increase less sharply when approaching water surface?

Any expert ready to comment?

 

[NUCENG]

Why then radiation increases strongly when approaching water?
Doesn't this indicate water surface emitting high radiation?


Sadly shielding obstacles like walking girders aren't shown in Tepco presentation chapter 3 to help explain radiation measurements. They are only indicated in chapter 2.
If torus is watertight, wouldn't radiation increase less sharply when approaching water surface?

Any expert ready to comment?

Time, distance and shielding are the watchwords for assessing radiation doses.

Distance: If the water is contaminated, approaching it would result in increasing radiation. If the trus is the source and you are getting clo=ser to it as you approach the water, the same applies.

Shielding: As you get closer to the water you may be going into an area with less shielding. The torus itself is partly above the water level. Any contamination in the atmosphere of the torus or deposited on the structures inside the torus has only the thin shell of the torus as shielding. Core debris inside the containment may be creating radiation streams near the vents between the containment and torus.

Time: has any pumping operation been done which could have stirred up contamination? Does the radiation level change over time (other than decay) showing priods of increase and decrease?

If there is information on the makeup of the radiation (by isotope) or much more detailed geometry information you may start to chip away at this problem. Good luck.

 

[Tepconium-311]

Dear NUCENG, thank you for reply!

If I understand you correctly, published Tepco data only reveals high radioactivity in torus room, but not where it is from.
Your explanation sounds really convincing that there is something dangerous in torus, torus vents or nearby.

But, another thing I don't understand yet.
Somebody mentioned (iirc) that torus room of unit 1 is above groundwater level.
If this is correct, then this cannot be groundwater.

Can there be other paths for cooling water to reach basements than via leak in torus?
Because, if torus is watertight, how can there be so much radioactive water in reactor and turbine buildings' basements??

Sounds contradictory to me.
So, in other words, is there any real chance that torus is _not_ damaged?

 

[r-j]

What kind of radiation are they measuring?

 

[SteveElbows]

Regarding the reactor 1 torus room, is it fair to say that we should be considering some corium blowdown into the torus room as a possibility here? High radiation readings and TEPCOs typically understated comments about 'sediment' tempt me to wander in that direction, especially given the smaller physical size of reactor 1 containment and the length of time it went without water injection.

 

[SteveElbows]

Can there be other paths for cooling water to reach basements than via leak in torus?
Because, if torus is watertight, how can there be so much radioactive water in reactor and turbine buildings' basements??

Sounds contradictory to me.
So, in other words, is there any real chance that torus is _not_ damaged?

At least one study of mark 1 containment failure mentions the blowdown that I was just talking about. I wil try to find the study, but in a nutshell this process does not have to involve the torus itself being damaged. Rather core material that is splattered across the floor of containment eats away at the steel wall near to where it meets the steel floor, and gets into the space between the concrete and the large pipes (downcomers?) that connect containment to torus. This offers a pathways whereby core material can get into the torus room, without having to pass through the torus itself. This would also open up a pathway through which water injected into containment later on could get to the torus room.

There may be some technical inaccuracies in this description but its the best I can offer without having the report to hand.

Of course I do not mean to suggest that we now have anything like solid proof that this happened, just that we should consider it as a possibility given the survey.

 

[SteveElbows]

Having now watched the video and seen how much material they disturbed with the probes, I would like to retract by comment about the sediment.

 

[tsutsuji]

The 7th mid long term meeting was held on 25 June: http://www.meti.go.jp/earthquake/nuclear/20120625_02.html

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

25 June 2012 government-Tokyo Electric mid and long term response committee, steering committee (7th meeting)

http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02a.pdf Agenda
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02b.pdf Participants

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02c.pdf Abstract of the proceedings of 6th steering committee meeting

Document 2: Plant status
Document 2-1: Plant status
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02d.pdf Plant parameters
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02e.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/120625/120625_02f.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02g.pdf Unit 2 alternative thermometers installation progress status

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02h.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02j.pdf Status of multinuclide removal facility (ALPS) qualification test and installation works, and characteristics of waste objects
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf Subdrain purification test report
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02m.pdf Progress status of construction of underground water storage tanks
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02n.pdf Progress status of ground water bypass study

3-3 Countermeasures to reduce environmental radiations
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02p.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02q.pdf Management of debris, cut down trees, generated by the response to the accident
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02r.pdf Countermeasures against fire of cut down trees (branches, leaves and roots) during the summer season, and future plans.
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02s.pdf Suitability tests of decontamination techniques within plant premises
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02t.pdf Consequences on water quality of the covering of the sea floor in the harbour (as of June)
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02u.pdf Results of evaluation of additional releases from reactor building's primary containment vessels
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02v.pdf Results of yearly radiation exposure at the plant premises boundary (as of June)

3-4 Improvement of working conditions
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02w.pdf Schedule

3-5 Countermeasures for spent fuels pools
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02x.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02y.pdf Debris removal work, reactor building top part, unit 3
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02z.pdf Debris removal work, reactor building top part, unit 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02aa.pdf Results of seismic safety study taking into consideration local outer wall bulging at Fukushima Daiichi unit 4 reactor building
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02bb.pdf Performance of preliminary underwater surveys (2nd and 3rd ones) in spent fuel pool for the purpose of removing debris at unit 3.
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02cc.pdf Performance of dry cask temporary storage facility construction work
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02dd.pdf Results of survey inside Fukushima Daiichi unit 2 reactor building (3rd ～ 5th floors)

3-6 Preparations for fuel debris removal
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02ee.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02ff.pdf Performance of survey into unit 1's torus room

3-7 treatment and disposal of radioactive waste
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02gg.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02hh.pdf Status of contaminated water analysis
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02jj.pdf Collection of samples to analyse debris and cut down trees

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02kk.pdf roadmap progress (abstract)

Document 5
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02mm.pdf Violations of safety regulations reflected in the first fiscal 2011 safety inspection at Fukushima Daiichi nuclear power plant (additional instructions)

25 June 2012 government-Tokyo Electric mid and long term response committee, technical development progress headquarters (7th meeting) (http://www.meti.go.jp/earthquake/nuclear/20120625_01.html )

http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_01a.pdf Agenda

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_01b.pdf Abstract of the proceedings of 6th meeting

Document 2
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_01c.pdf Decided projects for the global radiation reduction plan

Document 3
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_01d.pdf Securing education and human resources as seen from the mid and long term perspective

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_01e.pdf Organization of the "Fukushima Workshop" (provisional name) on development of machinery and equipments etc. toward the decommissioning of Tokyo Electric Power Company (K.K.) Fukushima Daiichi nuclear power plant

 

[clancy688]

At least one study of mark 1 containment failure mentions the blowdown that I was just talking about. I wil try to find the study, but in a nutshell this process does not have to involve the torus itself being damaged.

Here you go:

http://www.osti.gov/bridge/servlets/purl/5835351-nR29Hq/5835351.pdf

 

[zapperzero]

Does anyone know what is the current status of PCV equipment hatches in Unit 4?

Furthermore, were they supposed to be open, or closed, at the time of the accident?

 

[tsutsuji]

The 7th mid long term meeting was held on 25 June:

3-5 Countermeasures for spent fuels pools
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02bb.pdf Performance of preliminary underwater surveys (2nd and 3rd ones) in spent fuel pool for the purpose of removing debris at unit 3.

Translation:

1/4

2/4

 

[tsutsuji]

Translation:

3/4

4/4

 

[jim hardy]

in this document linked above (thanks again Tsutsuji )
http://www.meti.go.jp/earthquake/nuc...120625_02y.pdf

there's two red circles on bottom left photo.
800 % is about all the expansion it'll stand, and i don't see what is significant there.
Except that a lot of debris has been cleared.

is there anything I'm missing by my inability to read the captions ?

old jim

 

[SteveElbows]

No you aren't missing anything, debris removal is all its about. In this case they finally dealt with the roof debris that's been dangling down there, having previously cleared away rather large quantities of debris & broken buildings from the area below.

Since I was asking about progress at this reactor the other day, I am very grateful for the translation above which gives us a sense of timescale, as well as these new images.

 

[SteveElbows]

Here you go:

http://www.osti.gov/bridge/servlets/purl/5835351-nR29Hq/5835351.pdf

Thanks very much, that's the one, not sure if there are any others.

Anyway I guess we aren't going to learn much more about this for a long time, and there is little else that I can use right now to build on any theories in this regard. I suppose alternative possibilities are core material washing down into S/C or torus room later, or something related to wet venting.

The next thing we might learn about reactor 1 is the state of the TIP room, and updated measurements of previously inspected southern parts of the first floor, as they are due to do the robot thing there on wednesday according to this handout:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120703_01-e.pdf

 

[tsutsuji]

The 7th mid long term meeting was held on 25 June: http://www.meti.go.jp/earthquake/nuclear/20120625_02.html

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02n.pdf Progress status of ground water bypass study

This document was already translated into English by Tepco in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf pages 4/17 to 8/17 (only the date is different [25 June instead of 18 June])

The 7th mid long term meeting was held on 25 June: http://www.meti.go.jp/earthquake/nuclear/20120625_02.html

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf Subdrain purification test report

Most of this document was already translated into English by Tepco in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf pages 12/17 to 17/17:

http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 2/7 content similar with http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 14/17 "Complete the pumping test" was achieved on 15 June for unit 1 and 19 June for unit 2.
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 3/7 translated in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 15/17
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 4/7 translated in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 13/17
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 5/7 content similar with http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 14/17
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 6/7 translated in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 12/17
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02k.pdf 7/7 translated in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 17/17

 

[Azby]

The English-language executive summary of The Fukushima Nuclear Accident Independent Investigation Commission was just released a few minutes ago. You can download it from here:

http://naiic.go.jp/en/

 

[SteveElbows]

The English-language executive summary of The Fukushima Nuclear Accident Independent Investigation Commission was just released a few minutes ago. You can download it from here:

http://naiic.go.jp/en/

Thanks. Of particular relevance to the discussion of technical matters is the following from page 31:

The government-run investigation committee’s interim report, NISA’s “Technical Findings,” and specifically TEPCO’s interim report, all concluded that the loss of emergency AC power—that definitely impacted the progression of the accident— “was caused by the flooding from the tsunami.” TEPCO’s report says the first wave of the tsunami reached the site at 15:27 and the second at 15:35. However, these are the times when the wave gauge set 1.5km offshore detected the waves, not the times of when the tsunami hit the plant. This suggests that at least the loss of emergency power supply A at Unit 1 might not have been caused by flooding. Based on this, some basic questions need to be logically explained before making a final determination that flooding was the cause of the station blackout.

4. Several TEPCO vendor workers who were working on the fourth floor of the nuclear reactor building at Unit 1 at the time of the earthquake witnessed a water leak on the same floor, which houses two large tanks for the isolation condenser (IC) and the pip- ing for IC. The Commission believes that this was not due to water sloshing out of the spent fuel pool on the fifth floor. However, since we cannot go inside the facility and perform an on-site inspection, the source of the water remains unconfirmed.

5. The isolation condensers (A and B2 systems) of Unit 1 were shut down automatically at 14:52, but the operator of Unit 1 manually stopped both IC systems 11 minutes lat- er. TEPCO has consistently maintained that the explanation for the manual suspen- sion was that “it was judged that the per-hour reactor coolant temperature excursion rate could not be kept within 55 degrees (Celsius), which is the benchmark provided by the operational manual.” The government-led investigation report, as well as the government’s report to IAEA, states the same reason. However, according to several workers involved in the manual suspension of IC who responded to our investiga- tion, they stopped IC to check whether coolant was leaking from IC and other pipes because the reactor pressure was falling rapidly. While the operator’s explanations are reasonable and appropriate, TEPCO’s explanation is irrational.

6. There is no evidence that the safety relief (SR) valve was opened at Unit 1, though this should have taken place in the case of an accident. (Such records are available for Units 2 and 3.) We found that the sound of the SR valve opening for Unit 2 was heard at the Central Control Room and at Unit 2, but no one working at Unit 1 heard the sound of the Unit 1 SR valve opening. It is therefore a possibility that the SR valve might not have worked in Unit 1. In this case, a minor LOCA caused by the seismic motion could have taken place in Unit 1.