Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

Translation [installment 6: RPV/PCV integrity assessment]

24/34

25/34

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120914/1345_chusuiryo.html On 13 September Tepco said the injection rate problem had been solved, but the injection rate declined again on 14 September (a 10% decline at unit 1 from 09:00 PM on 13 September to 01:00 AM on 14 September, and a decline from 01:00 AM to 07:00 AM at unit 2). In both caes the needed rates were secured. As a countermeasure, Tepco is increasing the injection rates. Tepco suspects foreign bodies are remaining in the pipes.

 

[etudiant]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120914/1345_chusuiryo.html On 13 September Tepco said the injection rate problem had been solved, but the injection rate declined again on 14 September (a 10% decline at unit 1 from 09:00 PM on 13 September to 01:00 AM on 14 September, and a decline from 01:00 AM to 07:00 AM at unit 2). In both caes the needed rates were secured. As a countermeasure, Tepco is increasing the injection rates. Tepco suspects foreign bodies are remaining in the pipes.

Guess it is not easy to put in a strainer just before the pipes enter the reactor when everything is seriously contaminated.

 

[tsutsuji]

]27 August 2012 government-Tokyo Electric mid and long term response committee, technical development progress headquarters (8th meeting) ( http://www.meti.go.jp/earthquake/nuclear/20120827_02.html )

Document 2
http://www.meti.go.jp/earthquake/nuclear/pdf/120827/120827_02c.pdf Progress status of development of machinery and equipments to prepare fuel debris removal

https://www.physicsforums.com/showthread.php?p=4064974&posted=1#post4064974 Translation [installment 1: abstract]
https://www.physicsforums.com/showthread.php?p=4068601&posted=1#post4068601 Translation [installment 2: remote decontamination]
https://www.physicsforums.com/showthread.php?p=4069889&posted=1#post4069889 Translation [installment 3: PCV leakage points identification]
https://www.physicsforums.com/showthread.php?p=4071111&posted=1#post4071111 Translation [installment 4: PCV repairs]
https://www.physicsforums.com/showthread.php?p=4073726&posted=1#post4073726 Translation [installment 5: surveys inside PCV]
https://www.physicsforums.com/showthread.php?p=4076720&posted=1#post4076720 Translation [installment 6: RPV/PCV integrity assessment]

Translation [installment 7: open competitive biddings]

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[tsutsuji]

Translation [installment 7: open competitive biddings]

30/34

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[tsutsuji]

Translation [installment 7: open competitive biddings]

33/34

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[tsutsuji]

Additional information about the long term research and development effort is included in the presentations from the 7 August "workshop on machinery and equipments toward the decommissioning of Fukushima Daiichi NPP" held in Koriyama city: http://www.meti.go.jp/earthquake/nuclear/20120810_01.html

http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01b.pdf Program
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01c.pdf Presentation (1) Middle and long term roadmap and research and development
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01d.pdf Presentation (2) Fukushima Daiichi general situation
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01e.pdf Presentation (3) Practical use of technical catalogue public appeal results
Session 1:
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01f.pdf Development of remote decontamination techniques inside buildings
Session 2:
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01g.pdf Development of PCV leakage points identification techniques
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01h.pdf Development of PCV repair techniques
http://www.meti.go.jp/earthquake/nuclear/pdf/120810/120810_01j.pdf Development of PCV internal survey techniques

 

[SteveElbows]

If anyone wants a closer look at 'routine' reactor cap removal, they've posted images and video of the removal process from one of the reactors at the other Fukushima nuclear plant:

http://photo.tepco.co.jp/en/date/2012/201209-e/120914-01e.html

 

[Azby]

Interesting paper describing the use of muons to image the core of Fukushima Daiichi Reactor #1:

Cosmic Ray Radiography of the Damaged Cores of the Fukushima Reactors.
Konstantin Borozdin, et al.; Physical Review Letters, September 12, 2012

http://arxiv.org/pdf/1209.2761v1.pdf

The paper describes simulations, and concludes that it is feasible.

Azby

 

[zapperzero]

The paper describes simulations, and concludes that it is feasible.

The simulations they did were about imaging an in-vessel melt. I wonder if/how this would work with the core being dug into the concrete at the bottom of the drywell, as simulations show it probably is.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120922/index.html A little after 11:00 AM on 22 September, a 470 kg heavy steel frame fell into unit 3's spent fuel pool. That steel frame was located on the south-eastern pool side, and it was hit by the tip of a crane during debris removal work. The fallen frame's dimensions are 0.2 m x 0.3 m x 7 m. There is no variation of surrounding air radiations or radioactive substance concentrations in pool water. Pool cooling is going on. Tepco says they will use an underwater camera to check if there is any fuel damage. The NISA is checking if any procedure or management mistake was done.

http://www.tepco.co.jp/en/news/topics/1220971_2266.html English press release on that event
http://www.tepco.co.jp/en/news/topics/1220972_2266.html Cs concentrations in pool water

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120926/index.html Investigating with underwater camera into unit 3 spent fuel pool after the steel frame falling event, Tepco found other steel frame objects inside the pool, which are believed to have fallen during the hydrogen explosion. The underwater inspection started on 24 September, and by now around one eighth of the pool has been investigated and 3 steel frame pieces were found. One of them is immediately near a fuel rack. Tepco has not identified the piece that fell on 22 September, and believes the pieces found underwater are parts of the roof that fell during the hydrogen explosion. Having in mind that some fuel could be damaged, while radioactive substance concentrations and water level remain stable, the investigation is going on.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120925_01-e.pdf "Investigation of the Inside of Unit 3 Spent Fuel Pool Using an Underwater Camera at Fukushima Daiichi Nuclear Power Station"

http://photo.tepco.co.jp/en/date/2012/201209-e/120924-02e.html Steel frame falling video etc.

http://photo.tepco.co.jp/en/date/2012/201209-e/120925-01e.html underwater camera videos

 

[zapperzero]

Having in mind that some fuel could be damaged, while radioactive substance concentrations and water level remain stable, the investigation is going on.

Funny how this stuff was of no interest whatsoever until the new agency told them to do it.

 

[zapperzero]

http://www3.nhk.or.jp/news/html/20120926/k10015285931000.html

 

[a.ua.]

Punching an Access Hole at the Penetration of Unit 1 PCV at Fukushima Daiichi Nuclear Power Station
http://photo.tepco.co.jp/en/date/2012/201209-e/120927-01e.html
.start watching the 17 minutes.

 

[zapperzero]

There's water in there, which is good. Can't really tell, but I think I see convection. Maybe just compression artifacts though.

At 25 minutes in, they lose the feed and there is actual "snow" which makes me wonder once again, for the nth time, why in the name of Pete don't they use fiber optics instead of those el-cheapo CCTV cameras.

 

[nikkkom]

http://photo.tepco.co.jp/en/date/2012/201209-e/120924-02e.html Steel frame falling video etc.

We see substantial progress at Unit 3 - TEPCO removed a lot of debris on top.

 

[Tepconium-311]

There's water in there, which is good. Can't really tell, but I think I see convection. Maybe just compression artifacts though.

According to water condensation visible in penetration and chamber fixture there probably was at least some moisture in the containment atmosphere.
Could visible "steaming" and condensation have been caused by (possibly relatively cold) nitrogen gas injection?

But, why didn it rain cats and dogs inside containment?
Is this good or bad?

 

[Astronuc]

Karlsruher Institut für Technologie - Tracking developments at Fukushima since the earthquake and tsunami
http://www.kit.edu/besuchen/6042.php
http://www.kit.edu/visit/pi_2011_6054.php - summary in English

Much of it is in German, but there may some good records and some in English.
Erdbeben/Tsunami in Japan – Folgen für die nuklearen Anlagen in Fukushima

 

[turi]

Karlsruher Institut für Technologie - Tracking developments at Fukushima since the earthquake and tsunami
http://www.kit.edu/besuchen/6042.php
http://www.kit.edu/visit/pi_2011_6054.php - summary in English

Much of it is in German, but there may some good records and some in English.
Erdbeben/Tsunami in Japan – Folgen für die nuklearen Anlagen in Fukushima

Unfortunately the latest update is from March.

 

[Astronuc]

Unfortunately the latest update is from March.

There is this press release - http://www.kit.edu/visit/pi_2012_9010.php

Perhaps interest in the subject has declined since German federal policy is currently rather against nuclear energy.

Nevertheless, it is of archival interest.

 

[tsutsuji]

The last time I wrote "NISA", it was a mistake. The regulation job is now done by the NRA (Nuclear Regulation Authority). Website : http://www.nsr.go.jp/

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120926/index.html The NRA requests Tepco to write a report on the steel beam falling into pool problem by 3 October. The report shall include recurrence prevention countermeasures, and an estimate of the consequences and of the response, should a similar event cause pool damage and water leak.

 

[tsutsuji]

The 10th mid & long term meeting was held on 24 September 2012: http://www.meti.go.jp/earthquake/nuclear/20120924_01.html

1) Previous related topics:

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:

24 September 2012 government-Tokyo Electric mid and long term response committee, steering committee (10th meeting)

http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01a.pdf Agenda
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01b.pdf Participants

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01c.pdf Abstract of the proceedings of 9th steering committee meeting

Document 2: Plant status
Document 2-1: Plant status
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01d.pdf Plant parameters
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_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/120924/120924_01f.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01g.pdf High pressure flushing work and mock-up test results toward installation of alternative unit 2 thermometer
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01h.pdf Nitrogen injection into unit 1's suppression chamber
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01j.pdf Survey inside unit 1's PCV

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01k.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01m.pdf Multinuclide removal facility (ALPS) progress status
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01n.pdf Ground water bypass executive plan
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01p.pdf Additional tank installation plan

3-3 Countermeasures to reduce environmental radiations
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01q.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01r.pdf Seawater radioactive concentrations inside harbor
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01s.pdf Results of evaluation of additional releases from reactor buildings
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01u.pdf Radiation dose decline at site boundaries: Status report as of September

3-4 Improvement of working conditions
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01v.pdf Schedule

3-5 Countermeasures for spent fuels pools
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01w.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01x.pdf Debris removal work, reactor building top part, unit 3
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01y.pdf Debris removal work, reactor building top part, unit 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01z.pdf Report on unit 4 fresh fuel survey
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01aa.pdf Underwater survey (survey No. 2) into unit 3 spent fuel pool for the purpose of inside pool debris removal
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01bb.pdf Common pool water quality management
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01cc.pdf Fukushima Daiichi unit 3 reactor building steel frame sliding and falling into spent fuel pool event

3-6 Preparations for fuel debris removal
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01dd.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01ee.pdf Survey of accumulated water inside unit 1 reactor building triangle corner

3-7 Treatment and disposal of radioactive waste
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01ff.pdf Schedule
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01gg.pdf Debris, cut down trees management status
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01hh.pdf Cut down trees (branches, leaves, roots) temperature monitoring status
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01jj.pdf Contaminated water analysis results

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01kk.pdf roadmap progress (abstract)

24 September 2012 government-Tokyo Electric mid and long term response committee, technical development progress headquarters (9th meeting) ( http://www.meti.go.jp/earthquake/nuclear/20120924_02.html )

http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02a.pdf Agenda

Document 1
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02b.pdf Abstract of proceedings of 8th meeting (draft)

Document 2
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02c.pdf Abstract of progress status of "Grasping characteristics using mock-up debris, development of debris treatment technology"

Document 3-1
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02d.pdf Status of technical study by the remote technology task force

Document 3-2
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02e.pdf The NEDO's disaster unmanned-ization system

Document 4
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_02f.pdf Abstract of results of technical entry public appeal targetting mainly Fukushima Prefecture businesses, etc., concerning machinery and equipments development toward the decommissionning of Fukushima Daiichi nuclear power plant

 

[SteveElbows]

According to water condensation visible in penetration and chamber fixture there probably was at least some moisture in the containment atmosphere.
Could visible "steaming" and condensation have been caused by (possibly relatively cold) nitrogen gas injection?

But, why didn it rain cats and dogs inside containment?
Is this good or bad?

I've yet to see a full analysis of that footage from reactor 1 containment yet. I didnt read too much into the lack of falling water compared to reactor 2, I was just assuming it means the path of the water being sprayed into the reactor doesn't go anywhere near where this camera went.

Its tempting to say that the most obviously notable thing about the video is the debris, but I don't really have any idea what I am looking at. Is the camera pointing down or towards the pedestal area? Are we seeing a square opening in the pedestal which is normally used during maintenance to replace control rods etc?

Anyway I wasnt expecting that video to exist as early as it did, going by the timetable there is further exploration of reactor 1 containment to be done in the first part of this month, so I hope to learn something more useful from that! What little we do now know about conditions in both the torus room and containment does have the potential to tell a story with dramatic new detail, but actually getting to a point where such a story is clear and likely may still take some time.

 

[tsutsuji]

http://www.tepco.co.jp/en/press/corp-com/release/2012/1221349_1870.html "As for the installation of Unit 2 RPV alternative thermometer, the RPV pressure was found to be higher than that measured during the mockup testing. At 10:33 PM on October 1, the flow rate of the nitrogen injected into Unit 2 PCV was changed from 5m3/h to 0m3/h (the amount of nitrogen injection into the RPV remains the same). As the amount of nitrogen injection into the RPV has been maintained at 15m3/h (the necessary minimum flow rate: 9m3/h), there should be no impact on safety. Due to the change in nitrogen injection amount, the monitoring of the hydrogen concentration in the PCV, PCV pressure, PCV ambient temperature and reactor pressure has been enhanced. As the RPV pressure has decreased (6kPa as of 5:00 AM on October 2), insertion of the coil guide (functions as a guide for thermometer installation) started at 9:39 AM on October 2. The insertion was completed at 11:57 AM on the same day."

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_121003_01-j.pdf 3 October 08:30 Start of alternative thermometer insertion work. 11:03, same day, installation is completed. As of 11:00 the measured temperature on the said thermometer was 42.6°C. It is confirmed that it is roughly the same temperature as the 46.1° measured at 11:00 on the monitoring thermometer on the RPV lower part (TE-2-3-69H3)

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121003_01-e.pdf Unit 2 RPV Alternative Thermometer Installation at Fukushima Daiichi Nuclear Power Station

 

[tsutsuji]

24 September 2012 government-Tokyo Electric mid and long term response committee, steering committee (10th meeting)

3-1 Cooling by closed loop water injection

http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01j.pdf Survey inside unit 1's PCV

1) Previous related topics:
https://www.physicsforums.com/showthread.php?p=3934954#post3934954 6th meeting (25 May 2012) Execution of internal survey into unit 1 primary containment vessel (PCV)
https://www.physicsforums.com/showthread.php?p=4058562#post4058562 9th meeting (27 August 2012) Execution of internal survey into unit 1 primary containment vessel (PCV)
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120927_02-e.pdf (27 September 2012) Punching an Access Hole at the Penetration (X100BPenetration) of Unit 1 PCV at Fukushima Daiichi Nuclear Power Station


2) Translation:

As most pages happen to be copies of August's presentation, I translate only the new materials found on pages 12-15 :

12/20

13/20

 

[zapperzero]

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121003_01-e.pdf Unit 2 RPV Alternative Thermometer Installation at Fukushima Daiichi Nuclear Power Station

Finally some trustworthy data.

 

[tsutsuji]

2) Translation:

14/20

15/20

 

[SteveElbows]

I remain somewhat frustrated by the lack of articles about the initial footage inside reactor 1 containment.

I think the most detail I've seen anywhere is in this article, which suggests that the lead plates that were supposed to be on the end of the penetration they used were missing, presumed melted.

http://www.yomiuri.co.jp/dy/national/T120928003442.htm

 

[tsutsuji]

I remain somewhat frustrated by the lack of articles about the initial footage inside reactor 1 containment.

I think the most detail I've seen anywhere is in this article, which suggests that the lead plates that were supposed to be on the end of the penetration they used were missing, presumed melted.

http://www.yomiuri.co.jp/dy/national/T120928003442.htm

Thanks. I was not aware of that.

Here is the transcript of the 27 September press conference:

http://genpatsu-watch.blogspot.com/2012/09/20129271730-1.html [Tepco spokesman, Mr Ono comments the video ( http://photo.tepco.co.jp/en/date/2012/201209-e/120927-01e.html )] : Yesterday the penetration hole opening work was completed without problem. A video is available. I would like to show it to you. This picture is the result of inserting a camera to see how the hole was opened and for checking the situation after the hole was opened in the penetration with a cutter. [...] [he explains as the camera passes the ball valve, then the hole in the penetration stop plate, etc...] We have come to the inner side of the PCV. [...] Here it was originally the flange's outer side where a lead plate is mounted for shielding, but it was understood that it fell down and it is removed. That's what it is, and there is no need to open another hole in the lead plate, and it was confirmed that the entry inside [PCV] is possible. [then he comments as the camera progresses further inside the PCV][...]

NHK's Yokogawa: [...] As there was no lead plate, is the schedule going to be advanced ?

Ono : As a whole, the work must progress carefully, so I think it will be carried out almost as expected in the schedule.

[That's all they say about the lead plate]

 

[elektrownik]

May be lead plates are deformed by heat and one of them fall off when they worked on drilling through the wall to enter PCV with the endoscope ?

 

[SteveElbows]

Thanks very much for the press conference details :)

I don't know if the plate(s) fell down or melted completely, its certainly assumed that it got hot enough in containment for that sort of thing to happen I guess.

I will say that if we look at the photo taken in the reactor building which shows where the penetration is, there appear to be stains around the top of the equipment hatch plug which seem to support the idea of heat, smoke etc. I am talking about the photo that can be seen on the page labelled 3 of the translation tsutsuji did a while ago: https://www.physicsforums.com/showthread.php?p=4058562#post4058562

 

[tsutsuji]

I was curious about the picture, extracted from the unit 1 PCV video, captioned "scattered debris" by Mainichi at http://mainichi.jp/select/news/20120928k0000e040161000c.html and by Tokyo Shimbun http://www.tokyo-np.co.jp/movie/news/120928.html 's comment "very small scraps of inside-vessel steel members can be seen", so I read the press conference transcript where I had left it, after Mr Ono's comment on the disappeared lead plate :

http://genpatsu-watch.blogspot.com/2012/09/20129271730-1.html From there the camera progresses forward. Exactly now we are almost at the exact entrance of the PCV. The camera moved just a little forward into the inside of the PCV. Just after leaving the penetration, there is a structural part there, which is a rail. There are such things as platforms for a number of equipments installed inside the PCV or rails, and, although we don't know what they are, we found that things looking like very thin scraps have fallen on it. There is a rail located immediately after passing through the penetration, and it can be thought that these have fallen and accumulated on that rail. The situation is that a number of this kind of long-shaped objects are lying in it. If we try to change the angle of view by rotating the camera, it is quite clear that they are pretty thin, but we think that at this stage it is still difficult to confirm what they are. [then he explains that the purpose, this time, was to check that the camera and measuring instruments can be inserted into the PCV, and as the result for this is positive, the camera is now going to be pulled back]

 

[zapperzero]

"very small scraps of inside-vessel steel members can be seen",

things looking like very thin scraps have fallen on it. There is a rail located immediately after passing through the penetration, and it can be thought that these have fallen and accumulated on that rail. The situation is that a number of this kind of long-shaped objects are lying in it. If we try to change the angle of view by rotating the camera, it is quite clear that they are pretty thin, but we think that at this stage it is still difficult to confirm what they are.

Those would be shrapnel, from a pipe most likely. Chemical analysis would tell us exactly what kind of steel, but I ain't holding my breath. There is still an evident unwillingness on the part of TEPCO to find out what has happened and what is happening, beyond the absolutely, immediately necessary.

 

[jmelson]

http://genpatsu-watch.blogspot.com/2012/09/20129271730-1.html From there the camera progresses forward. Exactly now we are almost at the exact entrance of the PCV. The camera moved just a little forward into the inside of the PCV. Just after leaving the penetration, there is a structural part there, which is a rail. There are such things as platforms for a number of equipments installed inside the PCV or rails, and, although we don't know what they are, we found that things looking like very thin scraps have fallen on it. [/QUOTE]
This sure looks like shavings from a machining operation, I wonder if it is from the boring
through of the hole.

Jon

 

[HowlerMonkey]

Yes, most likely from the drilling.

Certainly not shrapnel.

 

[zapperzero]

Yes, most likely from the drilling.

Certainly not shrapnel.

Only there was no drilling. There was supposed to be drilling because there was assumed to be a lead plate in the way. Only, the plate had melted probably and in any case it's gone. Those splinters are not lead, either. Lead would have had plenty of time to oxidize and those are rather shiny.

 

[HowlerMonkey]

Not believing shrapnel.

Maybe you could provide pictures of shrapnel that looks even remotely like the material from the video.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121010/index.html "Unit 1's PCV water level is 2.80 m" The PCV was inspected on 9 October and a video was released on 10 October. Falling drops of water (rain) were not observed like in unit 2. It is believed that the humidity is less than in unit 2. A working platform [the grating, I guess] is rusted over a large area. On that platform, an about 30 cm long rod was found. The accumulated water surface is seen shining below the platform. Tepco measured the water surface as being 2.80 m above PCV bottom. The highest measured radiation was 11.1 Sv/h, which can cause death in about 40 minutes. Tepco said the water level is almost as expected, the melted fuel at the bottom of the PCV is sufficiently cooled, and the finds have no impact on the decommissioning plans.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121009_01-e.pdf " Investigation Results of the Inside of Unit 1 PCV at Fukushima Daiichi Nuclear Power Station" (9 October)

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121010_01-e.pdf Investigation Results of the Inside of Unit 1 PCV at Fukushima Daiichi Nuclear Power Station (10 October)

http://photo.tepco.co.jp/en/date/2012/201210-e/121010-01e.html pictures and videos

 

[zapperzero]

http://photo.tepco.co.jp/en/date/2012/201210-e/121010-01e.html pictures and videos

And so we get to ask another round of questions.
The measured dose rate decreases with height, which makes zero sense to me. Any ideas?

 

[Rive]

And so we get to ask another round of questions.
The measured dose rate decreases with height, which makes zero sense to me. Any ideas?

If the models are correct then there are only a relative small amount of core debris still in the RPV and the rest, slumped down to the slump pit on the bottom of the PCV (and even lower than that as it burned some hole in the concrete) is shielded by water.

So for first look it looks OK for me.

Ps.: can't wait for the water sample. The low dose measured in the water can indicate that the corium has little direct connection with the cooling water.

 

[rmattila]

Ps.: can't wait for the water sample. The low dose measured in the water can indicate that the corium has little direct connection with the cooling water.

Or that a year-and-a-half of flushing with fresh water has washed away most of the water-soluble substances and only the less soluble material remains in place.

 

[Cire]

Or that a year-and-a-half of flushing with fresh water has washed away most of the water-soluble substances and only the less soluble material remains in place.

Or most of the core is still in the bottom of the RPV

 

[Rive]

Or most of the core is still in the bottom of the RPV

That would be a miracle... For the other two cores the models are not necessarily suggests the RPV-damage, but for unit 1...

Or that a year-and-a-half of flushing with fresh water has washed away most of the water-soluble substances and only the less soluble material remains in place.

I wonder if flushing through the turuses would reduce the radiation levels in the basements?
The contamination of the water in the basements are continuously falling, but the toruses are most likely still full with the stuff from the first days.

 

[Astronuc]

What would be found in the torus would have to be mostly insoluble. The radioactivity decreases with time, or otherwise the radionuclides have been transported either to collection systems or to the environment.

http://www.world-nuclear-news.org/RS-Unit_1_containment_vessel_investigated-1110124.html

An investigation is underway into the internal conditions of the primary containment vessel (PCV) of the reactor at unit 1 at the damaged Fukushima Daiichi nuclear power plant. Tokyo Electric Power Company (Tepco) said that the water level in the vessel has been found to be higher than previously estimated.

An investigation is underway into the internal conditions of the primary containment vessel (PCV) of the reactor at unit 1 at the damaged Fukushima Daiichi nuclear power plant. Tokyo Electric Power Company (Tepco) said that the water level in the vessel has been found to be higher than previously estimated.

Some retrospective - old news

http://eetd-seminars.lbl.gov/sites/eetd-seminars.lbl.gov/files/Fukushima1_Technical_Perspective_LBL_EEDT_04052011-1.pdf

 

[a.ua.]

.

Ps.: can't wait for the water sample. The low dose measured in the water can indicate that the corium has little direct connection with the cooling water.

Analysis Result of the Accumulated Water in Unit 1 PCV
at Fukushima Daiichi Nuclear Power Station

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_121012_02-e.pdf

 

[MikeIt]

Just a guess but shiny metal in the drywell could be mirror insulation. There's a fair amount of it. It's not out of the realm of possibility that the dynamic forces that resulted from the breach of the RPV by core debris also tore up some of this insulation and deposited some of it where the picture shows.

 

[tsutsuji]

24 September 2012 government-Tokyo Electric mid and long term response committee, steering committee (10th meeting)

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuclear/pdf/120924/120924_01n.pdf Ground water bypass action plan

1) Previous related topics:
https://www.physicsforums.com/showthread.php?p=3882136#post3882136 23 April 2012 Plan to reduce volumes of groundwater seeping into units 1~4 buildings by groundwater bypass
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120618_05-e.pdf 18 June 2012 Progress status of ground water bypass


2) Translation:

As pages 08/11 to 11/11 happen to be copies of older presentation, I translate only the new materials found on pages 01-07 :

01/11

 

[tsutsuji]

2) Translation:

02/11

03/11

04/11

 

[tsutsuji]

2) Translation:

05/11

06/11

07/11