Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

Only thing I can think of is that these penetrations were originally sealed and failed during the accident.

I think you are correct.

I have not found anything like a blueprint showing the detailed structure of those penetrations, but here is what I found :

On the Hitachi-GE website, a robot specification dated 9 November 2012 :

2.1.1 Objectives of the equipment and general system
(1) The first objective of the equipment to be developed consists of checking for any leaks from
the penetration areas of the wall surfaces of the torus rooms and triangular corners in the
basement of the nuclear reactor building.
(2) The second objective of the equipment to be developed consists of monitoring the remotely
operated vehicle underwater that is used to visually inspect the torus rooms and triangular
corners in the basement of the nuclear reactor building.

http://www.hitachi-hgne.co.jp/download/2012/20121109_28-e.pdf page 1/7 (English)

On the NRA website, a document distributed at the 7th meeting, dated 29 March 2013 of the Special atomic facility monitoring and assessment study group meeting :

http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_04.pdf page 20/36 (translation)

 

[tsutsuji]

NRA Special atomic facility monitoring and assessment study group, 7th meeting, 29 March 2013 (http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/20130329.html )

http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_99.pdf Agenda
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_01.pdf Equipment stop due to blackout at Tepco Fuksuhima Daiichi NPP
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_02.pdf Units 1 to 4 internal electric power source blackout incident (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_03.pdf Reply to comments on unit 4 SFP fuel removal safety (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_04.pdf Status of verifications concerning unit 4 SFP fuel removal (draft)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_05.pdf Radiation assessment in plant premises surroundings (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_06.pdf Observations about unit 1 torus room radiation measurement results (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_07.pdf Waterproofing countermeasures against ground water seeping in (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_08.pdf Partial revision of "Special atomic facility executive plan" (22 March release) (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_09.pdf Verification status of each remark
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_10.pdf Status of the study group's past deliberations etc. on executive plan

(reference)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0007_11.pdf List of measures demanded for Fukushima Daichi NPP in line with the special atomic facility designation [7 November 2012]
https://www.youtube.com/watch?v=xpwa2TCPxts
NRA Special atomic facility monitoring and assessment study group, 7th meeting, 29 March 2013

 

[NUCENG]

aren't they, though?

But you see, the entire thing reminds me of what doctors call symptomatic treatment
which is generally good at keeping people alive, not so much at curing them. I worry about reactivity. I worry about corium flows. I worry about new cracks in the piping. TEPCO is seemingly unconcerned and just dumps more water in when the "patient" gets too hot.

And their alternatives are what? Are there any indications that corium can still be in a molten state after 2 years? Has any radiological evidence of reactivity changes indicated an impending recriticality? They are injecting water through both feedwater and spray piping. Adjustments in these flows seem to demonstrate that at least some of the flow from both paths is getting where it belongs. Operating pressures of piping systems still in use are significantly lower that design conditions. Leaks or additional cracks are possible or even probable due to damage, corrosion, and poor chemistry, but required flows are fairly small and there are additional paths available. Time to respond is in terms of days, not hours as it was in 2011.

You are absolutely justified in your concerns about potential additional problems. Keep watching and questioning.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130404/index.html A little after 05:20 AM on 4 April the multinuclide facility stopped suddenly. As there was no abnormalty or leakage, it was found that an operator had mistakenly pushed a button. The facility was started again one hour later. The problem was not disclosed to national or local governments or mass media until 3 hours after it happened.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130405/1715_teishi.html Unit 3 SFP cooling stopped at around 2:30 PM on 5 April. An alarm signal was generated on a "power board". Tepco said it plans to restart the system today. Without cooling the pool heats at 0.15°C/hour and it would take 2 weeks without cooling to reach 65°C. There are 566 assemblies in the pool, including 52 fresh fuel ones.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130405/index.html Unit 3 SFP cooling was restarted at around 5:20 PM.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130405/1254_hanei.html There was a deliberation on energy and nuclear power at the national diet today. Prime Minister Abe said concerning the accident investigation "Some points that need study are remaining. As the government changed, we want to revise from zero, and resolutely conduct the research of the causes". NRA president Shunichi Tanaka said : "In order to find out if the SBO is due to the earthquake or to the tsunami, one needs to enter the site whose radiation is too high, and our investigation shall include such considerations. The research of causes is an important duty, and as the members in charge of the investigation were selected on March 27, we want to make things clear as quickly as possible".

 

[zapperzero]

And their alternatives are what?
You are absolutely justified in your concerns about potential additional problems. Keep watching and questioning.

Alternatives... I am concerned that the site is still not instrumented properly. We should know most everything by now, or at least all that matters. Water flows, state of piping. Thanks for the encouragement, there is not much I can do from the sidelines, except ask questions.

Are there any indications that corium can still be in a molten state after 2 years?

At one point a few months ago there have been some changes - thermometers failing mostly - that suggested new paths for the water, or corium shifting, or both. We don't know. Just looking at the thermal power that it can still make, there shouldn't be any of it that is still molten though, no? I mean, barring odd situations, such as a hot bubble in a very efficiently insulating ceramic foam or something? When I said "corium flows" I mostly meant in the past - the paths it took are assumed, not known.

Has any radiological evidence of reactivity changes indicated an impending recriticality?

We don't know. There are to my knowledge no neutron detectors anywhere near the reactor buildings. I haven't read any mention of anything like that. The (enormous amount) of assorted metallic debris that has already been removed has not been checked for neutron activation. And so on.

They are injecting water through both feedwater and spray piping. Adjustments in these flows seem to demonstrate that at least some of the flow from both paths is getting where it belongs.

I am not disputing that, evidently there is some water (a lot actually). We don't know how exactly it gets to where it is and we don't really know where it goes when it goes (well, to the sea eventually but...) and so the cooling loop is not really closed. That should be a cause of great concern, due to contamination issues. Yet it somehow isn't.

Operating pressures of piping systems still in use are significantly lower that design conditions.

There's that at least, yes.

Leaks or additional cracks are possible or even probable due to damage, corrosion, and poor chemistry, but required flows are fairly small and there are additional paths available. Time to respond is in terms of days, not hours as it was in 2011.

Small blessings.

I can think of at least one practical reason to FINALLY do a thorough check of the piping system - the water processing/storage facility is overloaded as it is, flows could probably be reduced even further, much further in fact if we (TEPCO really) actually knew where the water is needed and how to get it there.

 

[tsutsuji]

Special atomic facility monitoring and assessment study group, 6th meeting, 8 March 2013 (http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/20130308.html )

http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_99.pdf Agenda
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_01.pdf Reply to comments on multinuclide removal facility (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_02.pdf Multinuclide removal facility (line A) hot test evaluation (draft)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_03.pdf Special atomic facility risk assessment, etc. (reply to comments) (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_04.pdf Mid and long term process toward fuel debris removal (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_05.pdf Radiation assessment in plant premises surroundings (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_06.pdf Structural strength and antiseismic strength of unit 3 cover for fuel removal (reply to comments) (Tepco)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_07.pdf Verification status of each remark
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_08.pdf Status of the study group's past deliberations etc. on executive plan

(References)
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_09.pdf List of measures demanded for Fukushima Daichi NPP in line with the special atomic facility designation [7 November 2012]
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_10.pdf NRA's awareness of issues
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_11.pdf Opinions raised by outside expert at the last meeting
http://www.nsr.go.jp/committee/yuushikisya/tokutei_kanshi/data/0006_12.pdf Unit 3 cover for fuel removal structural strength and antiseismic strength

https://www.youtube.com/watch?v=Gqg54W9x6j4

 

[zapperzero]

Special atomic facility

What does this mean please? Is it some new classification? A new legal framework?

 

[tsutsuji]

What does this mean please? Is it some new classification? A new legal framework?

Yes. According to http://www.asahi.com/special/10005/TKY201211070747.html Tepco is legally bound under this designation, to submit its operation plan (including reactor monitoring, fuel storage, worker radiation exposure management, etc.) for approval to the NRA.

It sounds like it gives the NRA more power than it has on the other nuclear power plants.

 

[zapperzero]

Yes.
It sounds like it gives the NRA more power than it has on the other nuclear power plants.

Thank you.
This seems reasonable.

 

[tsutsuji]

http://www.tepco.co.jp/cc/press/2013/1226107_5117.html About 6.0X10³ Bq/cm³ was found on 5 April between the outermost sheet and the middle sheet (bentonite sheets) at underground storage tank No 2. Additional water analysis will be performed on 6 April.

http://www.tepco.co.jp/cc/press/2013/1226108_5117.html We are holding an extraordinary press conference about the underground storage tank No 2 at Tepco's main office [in Tokyo], at 01:30 AM, 6 April 2013 (or Fukushima press club room, Fukushima prefecture prefectoral office main building 2nd floor, Fukushima City).

http://www.tepco.co.jp/cc/press/2013/1226111_5117.html At present, underground storage tank No 2 contains 13,000 m³ of water. We plan to transfer 11,500 m³ of water from underground storage tank No 2 to underground water tank No 1 (which is at present empty). 11,500 m³ is the maximum operational volume of underground water tank No 1. As there is no ditch nearby, there is little probability that water flowed to the sea.

http://www.asahi.com/national/update/0406/TKY201304050526.html The underground water tank stores water after it has undergone decontaminating treatment.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130406/index.html Although cesium has been removed, radioactive strontium remains in the water stored at the underground tank. Strontium was found between the [bentonite] sheets and also very small quantities of strontium were found in the ground outside the tank. Tepco suspects the water is leaking from the underground tank into the ground. As the underground tank is 800 m away from the sea, and as there is no water ditch nearby, Tepco thinks the water has not leaked directly into the sea.

 

[tsutsuji]

What I wrote above contains a mistake. See the top left diagram on http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130406_03-j.pdf page 4/22. Only the outermost sheet (black) is a bentonite sheet. The other two (red sheets) are HDPE sheets. There is also a layer of concrete (gray) on the inner side. There are also long fiber non woven sheets (dot dash lines) between those sheets.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130406/index.html Tepco plans to transfer the water into the other underground tank using four pumps with a flow rate of approximately 100 tons/day, so that it will take more than 5 days.

 

[tsutsuji]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130407_03-j.pdf See the diagrams page 4/15 : Tepco thinks that there is a possibility that water leaked through the detector pipe's penetration into the sheets. The leakage point is thought to be located at a high elevation, because no sudden rise of the between-sheets water level was observed. Conversely, a low elevation leakage point would have created a sudden rise, because the water pressure increases with depth.

This explains why Tepco decided to lower the water level in underground tank No. 3 :

Reduce the water level of the underground reservoir No.3 from 95% to less than 80% (by safely
transferring the water to an unused underground reservoir)
...
The water will continue to be stored in the underground reservoirs for the time being
while maintaining the water level at approx. 80% (max.) or less which is the location of the leakage
detection hole on the upper part of the reservoir (which is assumed to be the leakage location).

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130408_02-e.pdf page 3/4

 

[tsutsuji]

From Asahi : leak could have been detected earlier ; unexpected consequences on the ground water bypass system can be feared:

The company also said April 7 it believes that radioactive water began leaking from the No. 2 tank around March 20.

The company has been monitoring water levels and radioactivity concentrations outside the tank. But only after the leak was detected did TEPCO find that water levels had started falling around March 20.

There were also signs of changes in radioactivity concentrations on March 20, but the company did not notice them until April 3.

[...]

TEPCO planned to pump up groundwater and release it into the sea before it enters the reactor buildings. That plan would be meaningless if the groundwater is already contaminated.

By Shunsuke Kimura http://ajw.asahi.com/article/0311disaster/fukushima/AJ201304080089

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130409/index.html Underground tank No. 1's leak occurred while it was only 55% full, so that the cause is presumed be different from what had been thought earlier for Underground tank No. 2 and No. 3.

 

[turi]

The personnel access lock on floor 1 in reactor 1 seems to have withstood the heat while a penetration nearby has leaked radioactive material (dose rate values are on the last page):

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130409_10-e.pdf

The access lock looks like it has gotten quite hot:
http://photo.tepco.co.jp/library/130409_01/130409_01.jpg
http://photo.tepco.co.jp/library/130409_01/130409_10.jpg

 

[etudiant]

The concern is that leaking highly radioactive water may gradually contaminate larger areas of the site.
Things are bad enough as is, working in a 50-100mSiv/hr environment would be much worse.
If that is the prospect, TEPCO will surely be forced to ocean dump this contamination.

 

[tsutsuji]

I was hoping Tepco would quickly translate into English the presentation shown by Tepco's president on 10 April about the countermeasures against the underground tank leaks, but at present only the Japanese version is available :

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130410_04-j.pdf As you can see on the first page, they plan to move all the water from all underground plastic sheet tanks to on-ground steel tanks : the H2 area tanks, the filtrate water tanks and the G6 area tanks. The green area on page 2/20 is a new area under study where they plan to install even more above ground tanks. The tanks at H8, G3, G4, G5, and G6 (violet) have yet to be installed. The tanks installation plan at G6 is explained on the diagram on page 3/20 which shows in pink the G6 storage capacity gradually increasing over April, May, and June 2013, while the water quantity stored in the underground tanks (in blue) gradually decreases as the water is moved into the above ground tanks. The diagram on page 7/20 explains the plan to pump contaminated water from the detector pipe and put it back into the tank, for the purpose of mitigating (preventing ?) ground water contamination. The map on page 12/20 shows (in violet) the location of the new monitoring holes that will be bored to monitor ground water contamination. The schedule on page 20/20 says the visual inspection of the detector pipe penetration at underground tank No. 2 should be completed on 17 April.

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201304110054 "TEPCO to stop using underground tanks at Fukushima plant"

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130410/index.html 0.11 Bq/cm³ of strontium, etc. was found in a sample of ground water taken on 9 April near underwater tank No. 1. As the salt concentration is stable, it is impossible to judge if this is evidence that the tank is leaking.

The design of those tanks (2 PE sheets, 1 bentonite sheet) had been disclosed by Tepco at the 25 June 2012 mid and long term meeting :

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

Document 3 Study and execution of each special plan

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120625/120625_02m.pdf Progress status of construction of underground water storage tanks

 

[tsutsuji]

Fukushima Daiichi decommissioning countermeasure promoting conference, 1st secretariat meeting, 28 March 2013 ( http://www.meti.go.jp/earthquake/nuclear/20130328_01.html )

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/130328/130328_01h.pdf Study toward the early implementation of inside-building closed loop and closed loop scaling down

Translation :
01/11

02/11

03/11

 

[tsutsuji]

Translation:

04/11

05/11

06/11

 

[tsutsuji]

Translation:

07/11

08/11

09/11

 

[tsutsuji]

Translation:

10/11

11/11

 

[etudiant]

Thank you, Tsutsuji-san, for this most informative summary.
With a chloride ion concentration at the 0.1-1.0% level, the RO concentrate is still much less salty than sea water. This begs for additional concentration.
If the dissolved solids in the concentrate could be separately sequestrated, it would drastically improve the storage situation. I am surprised that TEPCO does not appear to be pursuing this option. Is the residual radioactivity in the RO water such that further concentration is too risky?

 

[zapperzero]

I seem to recall 2 Sv/h beta and 22 mSv gamma?

 

[LabratSR]

Tsutsuji, Would you mind taking a look at this press release from today.

http://www.tepco.co.jp/en/press/corp-com/release/2013/1226375_5130.html

Thanks,

 

[LabratSR]

"Work Performed Today (April 12) in Response to the Leakage
from the Underground Reservoirs"

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130412_07-e.pdf

 

[LabratSR]

Investigation of Unit 2 Torus Room

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130412_08-e.pdf

 

[etudiant]

I seem to recall 2 Sv/h beta and 22 mSv gamma?

No argument the residues would be seriously radioactive.
Afaik, the Kurion zeolites were much more contaminated still.
The priority here is concentrating the contaminated solution to avoid slopping the radioactivity all over the place because the storage tanks are leaking.

 

[tsutsuji]

Tsutsuji, Would you mind taking a look at this press release from today.

http://www.tepco.co.jp/en/press/corp-com/release/2013/1226375_5130.html

Thanks,

It is very big. Over 1000 pages. I can't even find a table of contents in that press release.

This press release covers a number of revisions to this huge book, first made available on 7 December. The revision is explained in http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130412_03-j.pdf (5 pages)

This big book is what I was referring to as "operation plan" a few days ago in a comment on the "special atomic facility" legal framework :

Yes. According to http://www.asahi.com/special/10005/TKY201211070747.html Tepco is legally bound under this designation, to submit its operation plan (including reactor monitoring, fuel storage, worker radiation exposure management, etc.) for approval to the NRA.

It sounds like it gives the NRA more power than it has on the other nuclear power plants.

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130412_03-j.pdf page 2/5 emphasizes that the "special atomic facility" (I think Tepco's translation translating 特定 by "specified" instead of "special" in the 12 April English press release sounds a bit strange) status was granted to Fukushima Daiichi as a facility where emergency measures are being conceived after a nuclear plant accident occurred.

The present revision is the 6th revision, releasing the 7th version :

1) Original version, 7 December 2012 : http://www.tepco.co.jp/en/press/corp-com/release/2012/1223529_1870.html (http://www.tepco.co.jp/cc/press/2012/1223522_1834.html Japanese - providing a table of contents)
2) 25 December 2012 http://www.tepco.co.jp/en/press/corp-com/release/2012/1223836_1870.html
3) 11 January 2013 http://www.tepco.co.jp/en/press/corp-com/release/2013/1224161_5130.html
4) 7 February 2013 http://www.tepco.co.jp/en/press/corp-com/release/2013/1224626_5130.html
5) 22 March 2013 http://www.tepco.co.jp/en/press/corp-com/release/2013/1225784_5130.html
6) 29 March 2013 http://www.tepco.co.jp/en/press/corp-com/release/2013/1225978_5130.html
7) 12 April 2013 http://www.tepco.co.jp/en/press/corp-com/release/2013/1225978_5130.html

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130412_03-j.pdf page 4/5 says Most of the changes have already been publicly released in documents such as the presentations at the NRA's Special atomic facility monitoring and assessment study group.

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130412_03-j.pdf page 5/5 : Examples of revisions performed in each chapter :

◯ Long term storage plan regarding solid radioactive waste
◯ Specification for the units 1,2,3 reactor injection line via CST, reflecting design progress
◯ (about contaminated water treatment and liquid radioactive waste storage) Additions and corrections to structural strength and earthquake resistance assessment
◯ Additions on Philosophy of safety inspections, operation management and conservation management based on the consequences of units 5 and 6's accumulated water
◯ Updating of the data concerning estimated releases and gas waste radiation estimates
◯ Text adjustments (on fuel debris removal and decommissioning)

Now there is something I don't fully understand, which is the difference between the "Implementation of measures" book and the other book called "Facility Management Plan for Units 1-4" (mentioned for example at http://www.tepco.co.jp/en/press/corp-com/release/2013/1225467_5130.html ).

One very simple difference between the two is that the "Implementation of measures" book is also covering units 5 and 6.

 

[tsutsuji]

http://www.iaea.org/newscenter/mediaadvisory/2013/ma201309.html "An IAEA expert team will visit Japan this month at the request of the Japanese government"

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130413/index.html The 13 member inspector team will visit Fukushima Daiichi from 17 to 19 April. Team leader Juan Carlos Lentijo said "water processing is going to be the focus of the present inspection. We are going to survey in detail if workforce and organization, etc. are suitable".

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130413/2325_osen.html With 7.2 Bq/cm³, the ground water sample taken on 13 April outside underground water tank No 1 is 5 times more contaminated than the one taken on 12 April, so that it is thought that leakage is going on. Tepco will start transferring the water from underground tank No. 1 to above ground tanks on 14 April.

 

[LabratSR]

Tsutsuji, Thank you very much. I was just curious if there was anything interesting in there.

 

[Tepconium-311]

No argument the residues would be seriously radioactive.
Afaik, the Kurion zeolites were much more contaminated still.
The priority here is concentrating the contaminated solution to avoid slopping the radioactivity all over the place because the storage tanks are leaking.

Umm... isn't this "RO concentrate" with its 2 Sv/h beta and 22 mSv/h gamma surface level actually "[pre-]purified water" and "contaminated solution" at the same time, too?

See here for example.
Maybe this is to confuse people?

Actual "SARRY concentrate" slurry is much more radioactive, several sieverts gamma, as Tepco had to admit unintentionally, see here.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130419/2045_hairo.html The Fukushima Daiichi decommissioning countermeasure promoting conference (composed of Tepco, government, etc.) had a meeting on 19 April where it was decided to create a new panel whose task it to make proposals for drastic revisions of the decommissioning plan in order to reduce the production of contaminated water. At present, about 400 tons of contaminated water are produced every day, and leaks are occurring one after another. The panel will be chaired by professor Yuzo Onishi of Kansai university who is a civil engineering and ground water expert. NRA president Shuichi Tanaka is also a panel member. The panel will submit a report by the middle of next month.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130419/index.html In response to the fact that 14 subcontractor workers involved in the underground tank water transfer between April 6 and April 8, were not carrying dosimeters as required, the labour ministry instructed Tepco to perform suitable radiation exposure management. The workers are required to carry two different kinds of dosimeters. The 14 workers failed to carry the badge-type dosimeter on their fingers, and among them 6 workers carried on their breast a different type of dosimeter instead of the required electronic dosimeter.

 

[nikkkom]

At TMI it all ended up with all water filtered to a pretty low concentration (below regulatory limits for releases), but then distillated anyway, and discharged into the river. The distillation residue was stored as low-level waste.

This method basically releases only tritium.

I wonder why TEPCO isn't doing that. Holding up all this water until tritium decays would not be practical anyway, so why wait?

 

[tsutsuji]

Fukushima Daiichi decommissioning countermeasure promoting conference, 3rd meeting, 19 April 2013 ( http://www.meti.go.jp/earthquake/nuclear/20130419_01.html )

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01a.pdf Agenda
http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01b.pdf Participants

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01c.pdf Creation of Contaminated water treatment countermeasure committee (draft)

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01d.pdf Orientations for problems and solutions regarding contaminated water treatment countermeasures (draft)

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01e.pdf Orientations for problems and solutions regarding contaminated water treatment countermeasures (summary)

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01f.pdf Document distributed by Fukushima Prefecture (observer)

 

[tsutsuji]

Fukushima Daiichi decommissioning countermeasure promoting conference, 3rd meeting, 19 April 2013

http://www.meti.go.jp/earthquake/nuclear/pdf/130419/130419_01e.pdf Orientations for problems and solutions regarding contaminated water treatment countermeasures (summary)

On page 7/7 they say they will survey the existing technologies in Japan and abroad concerning tritium removal. They want to "promptly study" their feasibility.

 

[tsutsuji]

At TMI it all ended up with all water filtered to a pretty low concentration (below regulatory limits for releases), but then distillated anyway, and discharged into the river. The distillation residue was stored as low-level waste.

This method basically releases only tritium.

I wonder why TEPCO isn't doing that. Holding up all this water until tritium decays would not be practical anyway, so why wait?

I don't know if that answers your question, but in August 2011 we had the following information about the evaporation systems :

http://mainichi.jp/select/jiken/news/20110808ddm003040141000c.html Tepco decided to reduce the chemical pump's flow rate, while increasing the frequency of chemical injections. Without evaporation systems, the desalinating facility produces 1.5 times more high concentration salty water than freshwater. The two evaporation systems that were launched yesterday can bring this rate down to 30%.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110808_01-e.pdf "Diagram of Desalination System"