Fukushima Japan Earthquake: nuclear plants Fukushima part 2

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http://www.tepco.co.jp/nu/fukushima-np/roadmap/2018/images1/d180329_07-j.pdf
(in Japanese)

Pages 4-12: They will make a big opening in the West wall of the Reactor Building of Unit 2 and install an "antechamber" in front of that opening. The idea is that, at some point in the future (2020~) they plan to remove the whole roof and upper side of the reactor building, in preparation for the works for removing the fuel bundles stored in the SFP. Before that, they need to investigate the operating floor (5th floor) foor radiation and dust and take measures to decrease these, and in order to carry out these operations they will cut a 5m x 7m opening in the West wall. The antechamber will be air-tight and equipped with purification installatons and HEPA filters.The opening should be ready around June or July.

Pages 13-18: Progress on the installation of the new cover on the operating floor of Unit 3. In fact, as you know, the cover is completed. The drawings on page 15 show that at step 1 there are some insulation/shielding layers placed on the operating floor (not sure if this is a satisfactory answer to nikkkom's question at post 1623 above). 2 pages give info on the number of people who worked durign this phase and the amount of radiation they were exposed to. The schedule on page 18 shows that they are planning to begin removing the spent fuel from the SFP sometime in the 3rd trimester of Fiscal year 2018, so maybe mid October.
 
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What is the reason for thread closure, please?
Not closed, moving to part 2. After 14k posts it becomes a system performance issue.
Since it is at 16k I suggest moving to part 3
 
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etudiant

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Actually, I do think the slow but steady progress being made with the Fukushima cleanup is really newsworthy.
Somehow, the Japanese seem to have mastered the problem of pursuing a very difficult engineering project without falling prey to totally corrupt corporate log rolling, in contrast to the debacles in the US on similar projects such as Hanford or INEL. It would be useful to look at the contractual details, including the performance incentives, that are yielding such different outcomes.
 

jim hardy

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It would be useful to look at the contractual details, including the performance incentives, that are yielding such different outcomes.
I have to think it's largely cultural... at the end of World War Two we sent Edward Demming over there to teach 'statistical product quality administration'.
They established a business culture of "doing things well" .
But back home we ,... well..; have you ever seen that old movie "how to succeed in business without really trying" ?
 
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etudiant

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I have to think it's largely cultural... at the end of World War Two we sent Edward Demming over there to teach 'statistical product quality administration. They established a business culture of "doing things well" .
But back home we ,... well..; have you ever seen that old movie "how to succeed in business without really trying" ?
Well, corporate US has certainly drunk the Kool-Aid concept of 'shareholder value' as the primary measure of merit for business decisions.
So that mandates very different contractual standards than when business was based on relationships and trust as much as on the bid numbers.
It should not be impossible to develop such standards, but there is understandably not much interest on part of industry, while the government bureaucracy has little incentive to do so while money is abundant.
 

etudiant

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Not sure whether this alters the legal landscape, but apparently TEPCO executives told the regulators 4 days before the accident that the plant would be swamped in the event of a 15 meter tsunami. That tsunami estimate had been developed as part of an independent study earlier when TEPCO was considering building a seawall., but then decided not to proceed. A multi hundred billion dollar mis-judgment in retrospect.
 

jim hardy

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Not sure whether this alters the legal landscape, but apparently TEPCO executives told the regulators 4 days before the accident that the plant would be swamped in the event of a 15 meter tsunami. That tsunami estimate had been developed as part of an independent study earlier when TEPCO was considering building a seawall., but then decided not to proceed. A multi hundred billion dollar mis-judgment in retrospect.
Wow so somebody got through.. Not much they could've done in four days, though.
 

etudiant

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Wow so somebody got through.. Not much they could've done in four days, though.
It seems the actual tsunami assessment was done in 2007, with a 15.7 meter maximum estimated. The decision not to do anything dates from around that time.
The testimony to the regulators came much later, in what context I don't know.
Asahi Shimbun reported on April 11 2018. http://www.asahi.com/ajw/articles/AJ201804110051.html
 

jim hardy

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Our first good view of what happened under the RPV.
http://www.asahi.com/ajw/articles/AJ201804270041.html

Great find Cire, thank you.

The same subject is treated in this report, part of the regular update in Long- and Mid-term Roadmap released on April 26:
http://www.tepco.co.jp/nu/fukushima-np/roadmap/2018/images1/d180426_08-j.pdf
(Japanese only)
- The images taken during the investigation of Jan 2018 have been processed a lot and various new findings appeared.I will mention below just a few notes derived from the photos and text in this document.
- Page 10 as given by Acrobat reader: Pebble and sand size sediment layer which looks like something that was melted and then solidified is visible on the floor of the pedestal. Sediment is also deposited on the "cable tray" which is made of stainless steel 4mm thick, but it must have been cool enough, judging from the fact that the steel of the cable tray hasn't changed shape.
- Page 11: 3 puddles of water are observed on the floor (rather, on the surface of the sediment). Enough cooling is ensured, judging from the temperature (21 degrees Celsius).
- Page 12: sediment in one part of this area may be 70cm thick. Close to the CRD changing machine the thickness is believed to be more like 40-50 cm. Various structural remnants can be seen here (upper tie plate of a fuel bundle; pipe-shaped thing; spring-shaped thing.
- Page 14: pedestal walls show some peeling and roughness of the epoxy-based paint but no further damage.
- Page 15-16: they could identify some letters on the handle of that fuel bundle, but not all of them therefore they cannot say exactly where that fuel bundle was located in the reactor before the meltdown (theoretically can be any of the 132 blue squares on page 16).
- Page 23: Another fallen object which suggests a fuel bundle handle (1 cm thick) has been seen on the rails used for the rotation of the working platform.
- Page 24: Pipe-like fallen object, ~2 cm thick. Hard to say where it comes from.
- Page 25: Spring-like fallen object. Might be from SRNM or LPRM detectors (I don't know what those are...) or from a fuel bundle, as those things contain springs.
- Page 26-27: Rod-like fallen object.
- Page 28: something that looks like a plate, but examined more closely suggests a panel of grating covered by sediment.

Pages 35~ refer to Unit 3 PCV. Based on the images taken by the swiming robot they created a partial 3D map of structural elements in the PCV.
 
Looks about as expected...

TMI-2 cleanup was walk in the park compared to this mess...
 
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TMI-2 didn't suffer a 9.0 earthquake.
 
There’s a new 49 minute feature by NKH investigating some sustained high level radiation releases that occurred from the plant during the accident but have never been clearly understood or explained:

https://youtube.com/watch?v=CwlvPRpq7aw

It’s very well done with a lot of work gone in to tie information and masses of date together. Good breakdown of the program and it’s findings here:

http://www.fukuleaks.org/web/?p=16683
 
The massive regulatory/bureaucratic machine produced thousands upon thousands of pages on safety, and yet the recipe for handling the meltdown seems to be: "seal the reactor shut to avoid leaks of radioactive materials... and then pump water into it to cool it down". No one saw any problems with this idea? Really?
 
The massive regulatory/bureaucratic machine produced thousands upon thousands of pages on safety, and yet the recipe for handling the meltdown seems to be: "seal the reactor shut to avoid leaks of radioactive materials... and then pump water into it to cool it down". No one saw any problems with this idea? Really?
I think when you design and sell a plant based on the notion that it is too safe to fail, you can’t really then go on to clearly and explicitly plan for an event in which then does. It’s like the unsinkable Titanic not having enough lifeboats for the all passengers on board, once you bill a system as 100% safe and reliable even if something goes wrong, it’s suddenly really difficult if not politically impossible to then start talking about things like “in case we’re wrong and things go completely wrong, do this”. They sold it as fool proof so they kind of have to live that lie. Otherwise it’s 10 times more difficult to credibly suggest operating it in the first place.

As for on the Daiichi itself, I think even with manuals, I don’t know if the outcome would have been any different. Handbooks are only as good as the data you have to put into them. With no power and no reliable readings, they wouldn’t have had anything other than hunches to go on. Plus I think the doc highlights clearly, is that managing conditions in the pressure vessels was almost a side issue anyway. Almost all attention was focused on the dangerous condition of the unit 3 and 4 spent fuel pools. Falling water levels uncovering the fuel, damage from the explosions and no real effective containment over the pools if anything went badly wrong, they were clearly top priority. If they lost control there, eastern Japan could have been lost. In a full on crisis like this, even something as serious as keeping the pressure vessel contents cooled can be relegated to a side issue. Add to that the fatigue, undermanning and rising dose rates effecting who could go where on site, they had to pick their battles.

Was very impressed NHK pulled together so much information and with the incredibly tight timeline they established. They are really pursuing the events of the accident in incredible detail
 
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I think when you design and sell a plant based on the notion that it is too safe to fail, you can’t really then go on to clearly and explicitly plan for an event in which then does.
This might have been the reason before Fukushima.

But what are the reasons why filtered vents are not mandated in US even _after_ Fukushima experimentally demonstrated that meltdowns are a realistic possibility?

As for on the Daiichi itself, I think even with manuals, I don’t know if the outcome would have been any different. Handbooks are only as good as the data you have to put into them.
Well, they definitely could have properly engaged IC on Unit 1, if accident manuals has clear directives to do so in station blackout. Thus, Unit 1 could have been saved.

And if manuals would have sections directing them to do so, they could have vented RPVs of Units 2 and 3 down to atmospheric pressure _before_ fuel started to melt. This would have released small amounts of radioactivity, yes, but then they could start injecting water with much less powerful pumps, since there would be no pressure difference to fight against. Units 2 and 3 could have been saved, too.

In reality, and as the video above clearly explains, with no manuals, they tried to reach two opposing goals at once: keep RPVs pressurized, and pump water into them. It was not possible to achieve both at once.
 

etudiant

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Nikkom indicates that the NKH report highlights how most of the damage from the accident was because there was no early depressurization of the crippled reactors.
If this is a correct understanding, has depressurizing now become part of the regular accident mitigation procedure for nuclear sites more generally?
 

anorlunda

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That's quite an interesting article.
I don't know. The article gives far too little detail to judge whether the employee made his case well enough. Employees disagree with each other all the time. History will prove some of them to be right, but that does not prove the others were negligent.

But, I did like the article title: TEPCO worker: Boss scrapped tsunami wall for Fukushima plant. Clearly improved safety results from having no bosses. :wink:
 

jim hardy

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From the article:
Some experts were skeptical about the assessment, given that there were no archives showing a towering tsunami ever striking the area.
I've been under the impression since the early days after the incident that there were old stone markers on the hill above the plant indicating a high water mark from a thousand years ago.

https://www.smithsonianmag.com/smart-news/century-old-warnings-against-tsunamis-dot-japans-coastline-180956448/

but my memory could have altered facts in the intervening years. I couldn't testify today as to whether they're on that particular hill.

old jim
 

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