Japan Earthquake: nuclear plants

elektrownik

Look at this part "3.3.1. Core boil-off process and meltdown into lower plenum"

tsutsuji

Tanabe's core remelting theories were first mentioned on Physics Forum on http://www.physicsforums.com/showpos...ostcount=10864 (August 2011)

This was before Tepco revised its flow rate data for unit 3 http://www.tepco.co.jp/en/nu/fukushi...10909_06-e.pdf (September 2011). See http://www.physicsforums.com/showpos...ostcount=11193

I wonder why http://www.tandfonline.com/doi/full/...48.2011.636537 published in January 2012 is still using the older data in its "Figure 19:Injection water flow rate in comparison with MDHRFR in 1F-3".

elektrownik

But it use also some other data (temp and pressure).

MadderDoc

Perhaps due to the close timing collision between Tepco's publishing of revised flow estimates, and the finalising of this particular article; it was received on 11 August 2011 and the final version was accepted for publication on 16 September 2011.

MadderDoc

A photo sequence of the March 11th tsunami hitting Daiichi, recent released at:
http://photo.tepco.co.jp/date/2012/2...20709_01j.html

SteveElbows

The following is a version of the recent helicopter footage. Can see how far they have progressed with platform to east and south of reactor 3 at a few moments in the footage.

http://www.youtube.com/watch?v=QdBp0TPgaVQ

Sorry I couldn't find the original version of this video.

MadderDoc

Thank you, Steve. I think I've found the progenitor of that version, it is a published snippet of a video taken by a Kyodo News helicopter on July 5th 2012:
http://www.youtube.com/watch?v=-FgXPX5iYC4&feature=plcp

tsutsuji

http://www3.nhk.or.jp/news/genpatsu-...710/index.html Tepco released 33 new pictures of the tsunami in response to the Diet investigation commission pointing out the existence of unreleased pictures. The picture were taken by a contractor company employee who was within the plant premises. Among the pictures taken before the tsunami arrival, one can see the white spray of the rising wave while it approaches, and a tanker seeking refuge by getting out of the port. The pictures taken after the tsunami arrival show the violent muddy stream, a large container being carried away by the stream and these pictures let one know again about the violence of the tsunami. Then, we see employees who had taken refuge on a roof who are worryingly looking at the stream. Tepco had released 17 Fukushima Daiichi tsunami pictures in May 2011, but the present pictures had not been released until the Diet investigation commission pointed them out. Tepco said:"Among the taken pictures, we selected for public release those that are the easiest for understanding how the tsunami came. We would like to apologize for the insufficient points in provision of information".

http://www3.nhk.or.jp/news/genpatsu-...706/index.html The Diet's investigation commission report contains up to now unreleased transcripts of plant manager Yoshida's testimony where he says "the line of command was a mess" and contains his criticism of the interference by the Prime Minister's Office. Yoshida said: "If the Main Office had said "stop" [injecting seawater], that would be debatable, but there was no such instruction at all. A phone call came from supporting role Prime Minister's Office: what is this stop thing? As it is on phone, it is difficult to discuss. The line of command was a mess. I thought that in the end I would decide by my own judgement". [Also quoted by http://www.yomiuri.co.jp/dy/national/T120706003982.htm (English) and http://mainichi.jp/english/english/n...na010000c.html (English)]

SteveElbows

Reactor 3 torus room survey robot, which had sound monitoring equipment to listen for running water, got stuck and hasnt been retrieved. 360 mSv/h measured at side of the northern torus access hatch, 230 mSv/h in location where robot is stuck:

http://www.tepco.co.jp/en/nu/fukushi...20712_03-e.pdf

Some photos of upper levels of reactor 3, but quality is poor. Some of the images have some signs of interlacing lines, which suggests to me that its from a video, but no video has been released.

http://www.tepco.co.jp/en/nu/fukushi...20711_03-e.pdf

http://photo.tepco.co.jp/en/date/201...20711_02e.html

Images released as part of the announcement of completion of reactor 4 upper level debris removal, but they are all taken from unhelpful angles. Helicopter footage we've already seen was better than this stuff.

http://photo.tepco.co.jp/en/date/201...20711_01e.html

LabratSR

TEPCO to release footage of video conferences

http://www3.nhk.or.jp/daily/english/20120712_15.html

tsutsuji

http://www3.nhk.or.jp/news/genpatsu-...713/index.html No conspicuous damage was observed except the fact that the south-western door is broken.

http://www3.nhk.or.jp/news/genpatsu-.../0400_4gk.html The NISA approved the plan to retrieve 2 fresh fuel assemblies from unit 4 pool. The assemblies will be pulled with 4 wires. The operation will be controlled with the help of an underwater camera, and radiation measurement tools. The NISA said these safety measures are "appropriate". As a security measure concerning radioactive substances, Tepco will not announce the date beforehand.

http://www.meti.go.jp/press/2012/07/...120712003.html NISA approval for unit 4 fresh fuel assembly removal
http://www.meti.go.jp/press/2012/07/...20712003-3.pdf Figure 2 at the bottom of the page shows the rafter crane on the platform above the reactor well with two hooks. Figure 4 is the tool that will be used for inspecting the fuel at the common pool. This inspection is scheduled during the last ten days of August. Normally the radiation on the surface of the fresh fuel is 25 microsievert/hour.

http://www.tepco.co.jp/en/nu/fukushi...20712_05-e.pdf Unit 2 RPV Alternative Thermometer: SLC Pipe Soundness Confirmation.

Why isn't the pipe already filled with water from the RPV ? Is there a check valve or something preventing water from flowing downwards ?

At 10:35, "no more water could be injected from that point". Why not ? What is preventing the water from pouring into the RPV ?

Does this result (soundness of SLC instrumentation pipe is confirmed) mean that the core is not as badly melted as could be thought ? It sounds like at least that pipe did not melt.

Joffan

Thanks for for continuing reporting efforts tsutsuji.

As Tepco says, the amount of water injected into the pipe and the retention of pressure point to a blocked pipe. The 15L injected was way less than the (as-designed) volume of the pipe, 33L. So there is potentially crud in the pipe, perhaps corrosion products, and these are blocking the pipe. It's also possible that the pipe has distorted (by heat or mechanical impact) which could block and reduce volume, or that the RPV internal section of the pipe has been penetrated and blocked by corium; or a combination.

The "result" is that the SLC pipe is not currently usable as a thermometer insertion route. Exactly why is not yet determined.

tsutsuji

Thanks Joffan. I was perplexed by this "soundess is confirmed" conclusion in the Tepco handout.

http://genpatsu-watch.blogspot.fr/20...127131800.html [transcript of July 13's press conference] Junichi Matsumoto:

"Normally, it is thought that the injected volume obtained from the pipe's length and diameter is 33 litres. Of course, in the hypothesis where the pipe is open up to the RPV, we presumed that water would go on entering even after filling 33 litres of water, but the situation in yesterday's soundness check is that injection becomes impossible at around 15 litres, and after the water filling was stopped, we observed the pressure decline status.

Today, when we checked at around 10:00, it was about 100 kPa as shown above. Well, as it was not the water head value of 68 kPa or 56 kPa measured by the water elevation when the extremity is open, we are suspecting that the pipe is somehow clogged.

Therefore, about anything special that we could say about this pressure, well, we understood that probably it is clogged, and we want to check the status of this clogging.

Also, checking methods are currently under study, but as we had been carrying out the preparations for alternative thermometer insertion, at present we are checking if we could not look inside the pipe using an industrial endoscope with that method".

Joffan

Me too, but I can speculate that, as the pipe did hold a very considerable pressure for a long time, in one sense it is "sound" in that it is probably not leaking to the PCV. Or perhaps - you would know better than me - it's a mistranslation of the idea that the the soundness has been confirmed... bad.

tsutsuji

That's right. It was a mistranslation.

計装配管の健全性を確認　should have been translated as "checking instrumentation pipe soundess" or "we shall check instrumentation pipe soundness".

There is a second handout on the same topic dated July 13: http://www.tepco.co.jp/en/nu/fukushi...20713_04-e.pdf

tsutsuji

http://www3.nhk.or.jp/news/genpatsu-...718/index.html Tepco removed one of the 204 fresh fuel assemblies in unit 4 pool on 18 July, starting at around 9:00 AM. They plan to remove a second one soon.

http://www.sbs.com.au/news/article/1...om-Japan-plant "Television crews used helicopters to film the operation, defying requests from TEPCO"

http://www.youtube.com/watch?v=yqWJFJtCabk Asahi News

http://www.youtube.com/watch?v=UDMEBJwMkwI Fuji News

http://www.dailymotion.com/video/xs8...-yyyyyyyy_news JNN

Andres Arce

Does anybody know what that underwater tarpac is for ?
(at 01.22)
http://www.dailymotion.com/video/xs8...-yyyyyyyy_news