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The more political thread besides Japan Earthquake: nuclear plants scientific one

by jlduh
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zapperzero
#523
Oct17-11, 06:54 AM
P: 1,042
Quote Quote by NUCENG View Post
IF the boroscope will fit through instrument lines, and the lines are intact, and the boroscope can survive the process conditions, and if water clarity permits, and if rad levels permit access to the penetration area by personnel to install the boroscope, there are routes to the drywell via the drywell and suppression chamber instrument lines, to the vessel outside the shroud through the vessel pressure and level instrument lines, and to the lower plenum inside the vessel through core differential pressure lines.

Navigate the IF minefield and get your camera is there and photograph the debris. Now what will you use that information for? What could you see that would change what they are doing now? They are still trying to ensure that the fuel, wherever it is, is covered and cooled to below 100 degC. Boiling keeps things stirred up and would probably be detrimental to getting useful pictures. How long was it before they inserted cameras at TMI? Is it worth the dose and risk to do this now, before completing site cleanup and building the containment "tent" structures?

I am curious, too. I "hope" they plan to look for the fuel before they start trying to remove it, but if it isn't at the top of their ppriority list right now, I can understand that, too.
We keep having this conversation, which says a lot about my pig-headedness and your patience, both.

I think after the tents are up working inside the reactor buildings will be harder not easier for the reason that radioactive steam will still be wafting out even if all the water is below 100 degrees Celsius.

I do not know if it is worth the dose. Maybe it is. Depends on what one would find. I would at least try to put a borescope into the drywell, below the RPV bottom head.

I may see that I need to add more boron ASAP because there is fuel and it is in a nasty configuration.

I may see that the RPV is whole, or I may see that it isn't, which would probably affect the choice of cooling lines and help me minimize water use.

I may see other, unexpected things, such as severely cracked walls/floors, a big honking hole in the middle of the drywell floor into which the fuel is sinking and so on and so forth. Interesting stuff that may make me change my priorities radically.

I may see nothing, in which case I would retrieve the borescope, see what sort of dose it got and if it got hit by any neutrons and call it a day. Then you'd criticize me (rightly, because hindsight is always 100%!) for wasting time, money and exposing people to unnecessary risk.
Astronuc
#524
Oct17-11, 11:04 AM
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Assuming the core melted - from the top down - since the top would be first exposed if coolant was leaking from the bottom of the vessel, it is better to look from the top down - as was the case at TMI-2.

Alternatively, they could look at the outside of the RPV before opening it in order to determine any breaches to the primary systems and RPV. It may be possible that some pipes rupture, or some control rod drive mechanism (CRDM) housing tubes broke. That would be useful to know.

Some useful information on BWR details here - http://www.ansn-jp.org/jneslibrary/npp2.pdf
NUCENG
#525
Oct17-11, 01:40 PM
Sci Advisor
P: 916
Quote Quote by zapperzero View Post
We keep having this conversation, which says a lot about my pig-headedness and your patience, both.

I think after the tents are up working inside the reactor buildings will be harder not easier for the reason that radioactive steam will still be wafting out even if all the water is below 100 degrees Celsius.

I do not know if it is worth the dose. Maybe it is. Depends on what one would find. I would at least try to put a borescope into the drywell, below the RPV bottom head.

I may see that I need to add more boron ASAP because there is fuel and it is in a nasty configuration.

I may see that the RPV is whole, or I may see that it isn't, which would probably affect the choice of cooling lines and help me minimize water use.

I may see other, unexpected things, such as severely cracked walls/floors, a big honking hole in the middle of the drywell floor into which the fuel is sinking and so on and so forth. Interesting stuff that may make me change my priorities radically.

I may see nothing, in which case I would retrieve the borescope, see what sort of dose it got and if it got hit by any neutrons and call it a day. Then you'd criticize me (rightly, because hindsight is always 100%!) for wasting time, money and exposing people to unnecessary risk.

No criticism planned or intended. I have no argument with you personally and neither of us will make that decision.
tsutsuji
#526
Oct17-11, 09:52 PM
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P: 1,220
The IAEA is afraid that the Japanese government might set more severe decontamination standards than the IAEA is ready to accept:

The Japanese authorities (...) are encouraged to avoid over-conservatism which could not effectively contribute to the reduction of exposure doses.
http://nuclearsafety.gc.ca/pubs_cata...G129rev1_e.pdf advice 1 p. 4

for the next cropping season there is room for removing some of the conservatism
http://nuclearsafety.gc.ca/pubs_cata...G129rev1_e.pdf advice 8 p. 5
Instead of "As low as reasonably achievable", the IAEA's philosophy seems to be "as high as reasonably achievable" :

It is important to avoid classifying as “radioactive waste” such waste materials that do not cause exposures that would warrant special radiation protection measures.
(...)
Residues that satisfy the clearance level can be used in various ways, such as the construction of structures, reclamations, banks and roads.
http://nuclearsafety.gc.ca/pubs_cata...G129rev1_e.pdf advice 5 p. 5

This would allow the removed material to be used in selected applications, e.g. together with clean material in the construction of structures, banks, reclamations or roads that will not pose undue risks to members of the public.
http://nuclearsafety.gc.ca/pubs_cata...G129rev1_e.pdf p.12

Pursuing a management strategy for all of these contaminated materials as radioactive waste due to over-conservatism would lead to enormous challenges in the timely establishment of a completely new infrastructure with regard to human resources, transportation and large facilities for processing and storage.
http://nuclearsafety.gc.ca/pubs_cata...G129rev1_e.pdf p.19
zapperzero
#527
Oct18-11, 04:59 AM
P: 1,042
Quote Quote by NUCENG View Post
No criticism planned or intended. I have no argument with you personally and neither of us will make that decision.
This is all hypothetical, of course. But I expressed myself in that manner to emphasize the fact that I agree with you - such a venture may very well yield nothing but a net loss of time, money and human health.
etudiant
#528
Oct19-11, 07:59 PM
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P: 858
Quote Quote by tsutsuji View Post
The IAEA is afraid that the Japanese government might set more severe decontamination standards than the IAEA is ready to accept:



Instead of "As low as reasonably achievable", the IAEA's philosophy seems to be "as high as reasonably achievable" :

I had thought that the Japanese government response was painfully uncoordinated and minimalist. So the IAEA comments to me seemed to be a recommendation to focus on the big picture and maximize the relief rather than to waste effort on something impractical such as removing several inches of soil across very large areas.
Tsutsuji- sans comment really makes me sit up and reflect. Very interesting perspective.
joewein
#529
Oct20-11, 02:08 AM
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P: 192
My Letter to the Editor about radiation levels in Okutama/Tokyo and the lack of external venting scrubbers in Japanese BWRs was published in Japan Times today. I wrote it in reply to another LTE that appeared in the paper last Sunday.

Okutama is no Chernobyl

By JOE WEIN
Tokyo
I commend Giovanni Fazio in his letter of Oct. 16 for drawing attention to the fact that Okutama, with some of the highest radiation levels in Tokyo, is also a major source of drinking water for its 13 million people. However, he overstates his case when claiming "Tokyo tap water comes from an area with cesium contamination at levels equivalent to the Chernobyl evacuation zones."

A helicopter survey found most of the mountains around Lake Okutama to be contaminated with between 10,000 and 30,000 Bq/m² of cesium 137. The "permanent control zone" around Chernobyl is defined as 555,000 Bq/m² and more while the evacuated "closed zone" is polluted with 1,480,000 Bq/m² and more.

We would not even be discussing such numbers if Tepco had invested in a scrubber to filter the emergency venting system of its reactors. Thirty years ago Sweden installed the so-called FILTRA system at its boiling water reactors. None of the Japanese nuclear power stations have such external scrubbers, which would have been dirt cheap compared to now trying to decontaminate hundreds of square kilometers of polluted land. Their installation should be mandatory for any reactors allowed to resume power production.
rmattila
#530
Oct20-11, 05:16 AM
P: 242
Quote Quote by joewein View Post
Thirty years ago Sweden installed the so-called FILTRA system at its boiling water reactors.
To be accurate, FILTRA is the name of the large gravel bed installation installed only at the Barsebäck site - all other Swedish (and Finnish) BWR:s got a smaller wet scrubber system, called plainly "filtered pressure reduction system of reactor containment", or shortly "system 362".
tsutsuji
#531
Oct20-11, 07:21 AM
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P: 1,220
http://www.47news.jp/CN/201110/CN2011102001000778.html A petition requesting the decommissionning of all of the 10 nuclear reactors in Fukushima prefecture was passed at Fukushima prefectoral assembly.
tsutsuji
#532
Oct25-11, 09:37 AM
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P: 1,220
http://mytown.asahi.com/ibaraki/news...00001110250001 Ibaraki prefecture's nuclear safety commission has held its first open door meeting in its 32 year long history. On 24 October, the commission members heard the explanations of Tokai Daini NPP's plant manager about the NPP's safety measures. A wall able to withstand 15 m tsunamis will be built in three years' time.

http://www3.nhk.or.jp/news/html/2011...494961000.html The Atomic Energy Commission of Japan had a meeting on 25 October about the cost of severe accidents. An estimate of the cost of severe accidents under the hypothesis that such accidents occur from once in 500 years to once in 100,000 years is ¥ 0.0046 to 1.2 ¥ per kilowatt. The commission concludes that the cost of nuclear energy should increase from ¥ 5 to ¥ 6 (or ¥ 6 to ¥ 7) per kilowatt, and this is still the cheapest way of producing electricity. However one member pointed out that the cost of decontamination over wide areas (such as forests) and the cost of the disposal of the generated waste is not integrated in the estimate. According to him, the cost of severe accidents is 16 ¥ per kilowatt. His remark was added as reference in the report.
Martin Peters
#533
Oct26-11, 09:38 AM
P: 3
Thank you, Tsutsuji, for the extensive information you have provided.

The cost of energy that you mentioned is given in the original article in terms of yen per kilowatt-hour (not per kilowatt).
tsutsuji
#534
Nov1-11, 05:15 AM
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P: 1,220
Quote Quote by Martin Peters View Post
The cost of energy that you mentioned is given in the original article in terms of yen per kilowatt-hour (not per kilowatt).
Thanks for correcting the mistake.

http://www.yomiuri.co.jp/election/lo...OYT1T00194.htm & http://www.tv-asahi.co.jp/ann/news/w...211101003.html Three candidates (current mayor Kunio Hiramatsu, former governor Toru Hashimoto, and communist party's Koichi Watashi) of Osaka city's mayoral election (27 November 2011) advocate "exit from nuclear dependency". Osaka city owns 9% of Kansai Electric.
tsutsuji
#535
Nov2-11, 07:30 AM
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http://www.nikkei.com/news/headline/...E38297EAE2E2E2 Minister of economy and industry Yukio Edano reprimended NISA chief Hiroyuki Fukano for being late because the NISA, which had learnt about the risk of transient criticality at Fukushima Daiichi unit 2 late in the night of November 1, contacted the prime minister's office after 7 AM on November 2. According to cabinet chief secretary Osamu Fujimura, because temperature and pressure levels are stable, the NISA juged that "it is not a situation where a danger is immediately occurring" and waited until the next morning to tell the Prime Minister. Osamu Fujimura learnt about the events at around 9 AM after he came to the Kantei. Nuclear accident recovery is the government's top priority and information about possible nuclear fission must be passed to the government without delay, he said, criticizing the NISA.
URob
#536
Nov8-11, 12:34 AM
P: 11
Instead of "cold shutdown". How about "gassed up and ready to go".
ThinkToday
#537
Nov8-11, 12:33 PM
P: 172
I don't think taking the time to thoughtfully assess the cost (men/dose/money) v. benefit (information) of taking a look inside is a bad thing. I don't think a determination of what would be gained NOW and what would be changed NOW based on that look inside is a bad thing, especially if other assessment tools can be used. Beyond the obvious, my concern is the Japanese version of the NRC doesn't drag cleanup out the way it was at TMI, and end up with a systems (gasket/seal/pump/door/electronic monitoring, etc.) failures and rusted everything) because they weren't designed to be unattended for years on end. i.e. proceed carefully, but proceed.

As a former HP, I tend towards caution in opening things up and poking around. It would appear the “Lessons Learned” studies were left unread. I remember working at different sites in the US after TMI retrofitting systems identified from lessons learned. I’m curious if other countries took our lessons learned to heart. It seems like post accident cleanup strategies would be factored into plant design after TMI, and for that matter, after SL1. I think we’ve all gotten over the “it can’t happen here” thing. Anyone know what changed in Japan after TMI, if anything? I haven’t set foot in a plant for many years, but I’d think (hope) it’s better.
clancy688
#538
Nov13-11, 11:38 AM
P: 546
Outsourced from the main thread:

Quote Quote by Most Curious View Post
If I choose to be anti-nuke I want it based on sound science, NOT political considerations or activist driven pseudo science.
150.000 permanent displaced people are a perfect scientific reason, at least for me. I don't oppose nuke power because it's "killing more people than coal or whatever" - I oppose it because it has the capability to displace millions of people and wreck entire economies. If something goes wrong.

Let's take the current Fukushima example. The Tokyo metropolitan area is the economic hub and engine of Japan. It's the largest metropolitan economy of the world. One third of Japans GDP comes from Tokyo alone.
Let's imagine the whole Tokyo area would've been hit with 20-100 mSv/a+ radiation. First, we'd have over 30 million displaced people. And second, Japan would lose one third of its economy. The world would lose one third of Japans economy.
I don't even want to imagine the global recession which would've followed. A nightmare.

No burning coal plant has the ability to wreck entire economies. No gas plant. No wind turbine. If a dam fails, hydroelectric power may have the ability to wreak havoc over thousands of square miles. But there you can immediately start rebuilding everything once the water has drained. With a nuclear accident, you cannot. You have to wait for dozens of years until the nuclides are gone.
Astronuc
#539
Nov13-11, 01:24 PM
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Quote Quote by URob View Post
Instead of "cold shutdown". How about "gassed up and ready to go".
The Fukushima units 1-4 are history. Once they severely damaged the core, including control blades, possibly with some fuel melting, and then added seawater, those units are damaged beyond repair. Those units will have to be demolished.
SteveElbows
#540
Nov13-11, 02:06 PM
P: 630
Quote Quote by joewein View Post
My Letter to the Editor about radiation levels in Okutama/Tokyo and the lack of external venting scrubbers in Japanese BWRs was published in Japan Times today. I wrote it in reply to another LTE that appeared in the paper last Sunday.
Venting should be scrubbed as much as possible. However at Fukushima it seems likely that quite a lot of the contamination did not come from venting. For example various release estimate data suggests that reactor 2 was responsible for a lot of the contamination, and that reactor never got to vent through the stack. It is not possible to be completely sure about this because reactor 3 and the reactor building 4 explosion, along with any continued output from reactor 1, could be responsible for an unknown percentage of the emissions which fell on land on the March 15th peak. But at this point we certainly cannot rule out the prospect that far more than 50% of the contamination of Japanese land didn't come out through the proper venting path. Another factor is that the wind is though to have taken the initial reactor 3 venting emissions out to sea rather than contaminating the land.


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