Japan Earthquake: nuclear plants


by gmax137
Tags: earthquake, japan, nuclear
tsutsuji
tsutsuji is offline
#13789
Oct26-12, 04:12 AM
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http://www3.nhk.or.jp/news/genpatsu-...025/index.html On 24 October, Tepco inspected the top part of unit 1's reactor building using a balloon (diameter 2 m, height 3 m ). It was confirmed that although there are concrete debris, etc, the overhead crane and the fuel handling machine have not fallen. The radiation measured near the 2nd floor was 150 mSv/hour, and the one near the 5th floor was 85 mSv/hour. Tepco had tried to do this survey in August, but failed as the balloon hit some debris. This time they used a smaller diameter balloon, and were able to inspect the top part of the building for the first time.

http://www.tepco.co.jp/en/nu/fukushi...21024_02-e.pdf Results of Reinvestigation of Unit 1 Operation Floor at Fukushima Daiichi Nuclear Power Station (24 October 2012)

http://www.tepco.co.jp/en/nu/fukushi...20808_02-e.pdf 8 August 2012 balloon mission

[question: would it not have been easier to install one camera or two on the top beams of the cover/tent structure ? Or to put cameras on the crane that was used to build the cover structure ? (http://photo.tepco.co.jp/en/date/201...11008-02e.html : Installation Work of Roof Panels for Reactor Building Covers at Unit 1, Oct 08, 2011)]
westfield
westfield is offline
#13790
Oct27-12, 06:16 AM
P: 143
Quote Quote by tsutsuji View Post
<snip>

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

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

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

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

Video , U1, west side, FL5 Crane - Timestamped May 16 2011 (and yes, photobucket isnt very good for video :( )



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




Also, thankyou again for your reports.
zapperzero
zapperzero is offline
#13791
Oct28-12, 06:33 AM
P: 1,030
Quote Quote by tsutsuji View Post
would it not have been easier to install one camera or two on the top beams of the cover/tent structure ?
they should have put in a light rolling bridge type crane and an airlock
hindsight is 20/20 I guess and TEPCO's self-enforced lack of curiosity is infinite
Joffan
Joffan is offline
#13792
Oct30-12, 09:16 AM
P: 329
Quote Quote by tsutsuji View Post
would it not have been easier to install one camera or two on the top beams of the cover/tent structure ?
Indeed; even now, would it not be easier to instrument a replacement roof section with all sorts of sensors, including cameras, and then swap with one of the installed sections? Instead of messing about with balloons?
tsutsuji
tsutsuji is offline
#13793
Oct30-12, 12:06 PM
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It is Tepco's own idea. You can see green color cameras on the diagram on the last page at http://www.tepco.co.jp/en/press/corp.../110624e15.pdf

I wonder what happened to those cameras.

http://www3.nhk.or.jp/news/genpatsu-...030/index.html The investigation launched after the "pocket dosimeter in lead cover" problem revealed additional problems. Investigating the cases where both dosimeters [sounding like each worker always carries two of them?] had a difference higher than 25%, at least 20 cases of inappropriate radiation exposure management were revealed. They found 3 data input mistakes, 6 inappropriate management cases like the worker carries his dosimeter when he is off duty, and 11 cases where the lower of the two dosimeter values had been reported [sounding like the rule is to report the highest one]. However, no intentional misreporting was found. The ministry of labour and health instructed Tepco and 37 subcontractors to take recurrence prevention countermeasures.
tsutsuji
tsutsuji is offline
#13794
Nov7-12, 04:03 AM
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Asahi has a couple of stories in English:

Teleconference excerpts:

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

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

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

http://www3.nhk.or.jp/news/genpatsu-...10_taiguu.html An increasing number of workers resign because remuneration is worsening. At the start, I received 230,000 per month, and just before I resigned, I had only 180,000 and had to pay for lunch, a worker who resigned says. Another one who came from Kansai had 250,000 that decreased to 200,000 and he was asked to leave the company-paid ryokan where he was staying.

http://www3.nhk.or.jp/news/genpatsu-...105/index.html It was found by journalist investigation/interviews that the number of registered workers is 8000 instead of the 24,000 figure presented by Tepco. At present, 3000 workers are working on a given day. Tepco estimates it needs 11,700 workers for this year. Tepco asserted that it can secure this number, based on the fact that 24,000 workers have registered. Actually this figure is the number of workers who registered since the accident. Since then, 16,000 have cancelled their registration, and as of last month, only 8000 workers were registered.

http://www3.nhk.or.jp/news/genpatsu-...106/index.html Fukushima prefecture asked Tepco whether it can secure enough workforce. Tepco said "as the needed workforce per month is 6000, 8000 registered workers is enough".
SteveElbows
SteveElbows is offline
#13795
Nov11-12, 06:44 AM
P: 630
Quote Quote by ronaldkr View Post
Dear etudiant,
you are falling for a part of the never-ending witchhunt against chairman Jaczko. The problem at that time was not evaporation of the SFP at unit 4; they did not know if it lost water.
Sorry for the delay in replying to this, I've not been here for a few weeks.

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

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

Given that people didnt instantly catch on to the idea that the reactor well was full of water and the pool gate may have failed, and that they hadnt figured out why reactor 4 building exploded, its not really surprising that the worst scenarios for reactor 4 pool seemed credible in the early days.
tsutsuji
tsutsuji is offline
#13796
Nov18-12, 04:41 PM
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http://www3.nhk.or.jp/news/genpatsu-...117/index.html The NHK journalists tried to check again radiation doses. When they found something strange ("unnatural") in the radiation data from Fukushima Daini, 12 km South of the accidented plant, they asked Tepco for clarification, and the existence of until now undisclosed data was revealed. These undisclosed data cover a period from 15 March to 3 April 2011. They include the following March 16 data : the until then 20 microsievert/h radiation jumped to 80 microsievert/h at around 09:40 and 87.7 microsievert/h 10 minutes later. About one hour sooner, at around 8:30 white smoke had risen from the Fukushima Daiichi unit 3 reactor building, and the relationship between the smoke and the radiation peak at Fukushima Daini is being questioned. Kado Shinichiro of Tokyo University says: "For analysis, it is highly regrettable that unreleased data come out one year and 8 months after the accident. It is necessary to check the data, including the relationship between the peak and the white smoke at unit 3". Tepco says "we are investigating why the data were not released. We'll study a release of these data as the investigation progresses".

http://www.tepco.co.jp/nu/fukushima-...21114_01-j.pdf Tepco submitted to the NRA a change in the "mid-term safety principles"-based operational plan report. Unit 3's future cover structure is shown on diagrams.
zapperzero
zapperzero is offline
#13797
Nov19-12, 03:05 AM
P: 1,030
Quote Quote by tsutsuji View Post
it is highly regrettable
Understatement of the month. The worst thing about it is that we'd all be quite justified by now in going off the deep end and wondering "Ok, what else is TEPCO still conveniently failing to release? Gojira maybe? "
tsutsuji
tsutsuji is offline
#13798
Nov20-12, 12:27 PM
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http://www3.nhk.or.jp/news/genpatsu-...1755_date.html The data had been collected by hand, and they [including the unreleased ones?] had been reported to the government [NISA, I guess]. The released data were showing only every 10 minutes for one hour every three hours, instead of every 10 minutes. The missing data have been added on Tepco's website on 19 November 2012.

http://www.tepco.co.jp/nu/fukushima-...21119_02-j.pdf Tepco's explanation about the missing Fukushima Daini radiation data.

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

http://www.tepco.co.jp/cc/press/betu...es/110316d.pdf Japanese version for 16 March 2011 [the new completed version, I guess] [including the 80.0 and 87.7 microsievert/h figures at 09:40 and 09:50, Monitoring post MP-4]
ronaldkr
ronaldkr is offline
#13799
Nov20-12, 05:09 PM
P: 8
Quote Quote by SteveElbows View Post
...
Personally I think that as soon as the helicopter flight decided to dump water on reactor 3 pool rather than reactor 4 pool, we had clear signs of what the people with the best information at the time thought was the priority...
Well, I remember that the first helicopter flight was abandoned because of too high radiation exposure and subsequent flights were done with a lead plate mounted underneath. So they might well have thought that the problem was the "shine" of the unit 4 pool (i.e. more or less empty) and not the air-bound radiation from the emissions of unit 3 (and the others).

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

Probably somebody remembered that unit 4 was full of water and therefore less an imminent danger compared to the unit 3 pool, where they also did not know about water leaks.
SteveElbows
SteveElbows is offline
#13800
Nov22-12, 12:08 PM
P: 630
Quote Quote by tsutsuji View Post
http://www3.nhk.or.jp/news/genpatsu-...1755_date.html The data had been collected by hand, and they [including the unreleased ones?] had been reported to the government [NISA, I guess]. The released data were showing only every 10 minutes for one hour every three hours, instead of every 10 minutes. The missing data have been added on Tepco's website on 19 November 2012.

http://www.tepco.co.jp/nu/fukushima-...21119_02-j.pdf Tepco's explanation about the missing Fukushima Daini radiation data.

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

http://www.tepco.co.jp/cc/press/betu...es/110316d.pdf Japanese version for 16 March 2011 [the new completed version, I guess] [including the 80.0 and 87.7 microsievert/h figures at 09:40 and 09:50, Monitoring post MP-4]
Interesting stuff! The UK data has been updated now too.

Obviously when looking at this we have to take into account wind direction. I have started looking through data for the period after the 16th, to see if there are any other spikes which those articles dont mention.

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

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

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

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

Increases on March 22nd peaking around 14:20.

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

There were a couple of other times values temporarily rose in March but they were less significant numbers so I havent bothered to highlight them here.
SteveElbows
SteveElbows is offline
#13801
Nov22-12, 06:21 PM
P: 630
I've been looking back at some investigation reports that may not have been translated very quickly after they were first published. I was looking for details of interest to me that I dont remember being published in other reports we talked about here.

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

Page 61, in talking about possible leakage paths, notes that steam was seen escaping from a region of the upper part of damaged reactor 1 building that could be the concrete plugs above the vessel head. Its nice to see this mentioned, as it was infuriating that we saw this kind of thing on early video footage but there was no comment about it at the time. Sadly I dont think they make the same comments about reactor 3.

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

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

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

Page 75, they talk about time period where containment damage at reactor 2 may have already started to happen. The period they mention is from 13:45 to 18:10.
SteveElbows
SteveElbows is offline
#13802
Nov22-12, 07:39 PM
P: 630
The attachments are fascinating too. I've just posted about some pages of particular interest to the reactor 2 thread. I havent had time to read the stuff dealing with reactor 3 yet but here are a couple of highlights in regards reactor 1 and this document:

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

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

Pages 64-67 discusses radiation increases around 21:25 on March 14th and the possibility that this wasnt just down to reactor 2 or even reactor 3, but also further damage occurring at reactor 1.
Bandit127
Bandit127 is offline
#13803
Nov25-12, 12:26 PM
P: 180
Quote Quote by SteveElbows View Post
The attachments are fascinating too. I've just posted about some pages of particular interest to the reactor 2 thread. I havent had time to read the stuff dealing with reactor 3 yet but here are a couple of highlights in regards reactor 1 and this document:

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

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

Pages 64-67 discusses radiation increases around 21:25 on March 14th and the possibility that this wasnt just down to reactor 2 or even reactor 3, but also further damage occurring at reactor 1.
There is a lot more than that in there. A very good read.

Thanks for posting it.
Hiddencamper
Hiddencamper is offline
#13804
Nov25-12, 04:50 PM
P: 166
Quote Quote by SteveElbows View Post
The attachments are fascinating too. I've just posted about some pages of particular interest to the reactor 2 thread. I havent had time to read the stuff dealing with reactor 3 yet but here are a couple of highlights in regards reactor 1 and this document:

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

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

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

What's interesting is the unit 3 RCIC appears to had its mechanical trip latch fail. The trip latch, we often call it "the coathanger", seems kinda flimsy. You can see it in http://www.genassis.com/APSAFWPumpTerryTurbine.jpg this picture. It's the long thin bar going from the trip and throttle valve to the main body of the unit shaft and has a spring attached to it. The trip and throttle valve (on the left) has mechanical and electrical (solenoid) trip mechanisms. Most BWRs don't use the electrical trip during normal operation, and instead opt to close the steam supply valve instead, as the supply valve does not need an operator to manually reset it, while the trip and throttle valve requires a manual reset to lift the valve off its seat.

If the mechanical latch was what failed then the failure mode needs to be determined and confirmed as terry turbines (used for RCIC/HPCI/Aux feed) are used in a LARGE number of LWRs in the US and world.
SteveElbows
SteveElbows is offline
#13805
Nov25-12, 08:03 PM
P: 630
It was certainly a breath of fresh air compared to most of the reports we had to put up with for so long. I look forward to reading the rest of it, it was a bit too long to read properly in one go to say the least!

I should point out the site it came from in case anyone is interested in reading other documents that went with it:

http://icanps.go.jp/eng/final-report.html

If I combine it with the other final report that I've just been reading, which tends to focus on some different things, then I finally feel like I've got almost as much data, analysis and narrative as I could reasonably hope for until such a time as they are better able to ascertain detail of damage, fuel location etc.

http://warp.da.ndl.go.jp/info:ndljp/...apter2_web.pdf

(From http://warp.da.ndl.go.jp/info:ndljp/...ort/index.html )

Again just to highlight a few areas of interest to me, leaving out reactor 2 which I'm discussing in its own thread:

Page 31 seems to be suggesting this reports authors required a core-concrete interaction to generate sufficient quantities of hydrogen to explain the explosions at reactor buildings 3 & 4.

Pages 90-93 looks at whether the operation of SRVs at reactor 1 depressurised that RPV, or whether pipe damage due to the earthquake was responsible.

In some ways this report doesnt feel quite up to the same standard as the other one, and especially the above highlights may be controversial. But the way in which it looks at such issues, and its broader attempt to construct a narrative of the sequence of events at the reactors in a slightly different manner to the other reports, gives it some worth in my eyes, just not on its own. I highly recommend that anyone frustrated by failures of previous reports to at least mention possible remelts etc after the first stages of disaster at each reactor, eg dates such as 16th and 21st March, or failures to construct a readable narrative that focuses on important details rather than seem to willfully obscure, could do a lot worse than at least skim these documents.
tsutsuji
tsutsuji is offline
#13806
Nov27-12, 09:57 AM
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http://www.tepco.co.jp/en/nu/fukushi...21126_02-e.pdf Since the area surrounding the [PCV Gas Control System] duct in Unit 3 Reactor Building is high radiation area (Max.approx. 1Sv.h), the inspection will be performed by a robot with a camera attached. The inspection is scheduled on November 27 (and 28), 2012 (...) New Type Robot Name: FRIGO-MA.

http://www.tepco.co.jp/en/press/corp...3342_1870.html a TEPCO employee found that Unit 3 reactor injection water amount had increased from 5.8m3/h (as of 10:00 AM) to 7.0m3/h at 11:00 AM today [26 November] during the regular data check. (...) the cause of the increase in the reactor injection water amount was identified to be a worker unintentionally touching the handle to operate the flow rate adjustment valve.


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