Japan Earthquake: nuclear plants

Rive

I have a slightly better question to chew on: with all those makeup pipes all around, are they ready for the winter?

What would happen if some water transfer pipes gets blocked by ice? What would happen with the SFPs? With the makeup cooling of the SFPs?

NUCENG

If you are talking about the hoses and pipes at Fukushima, I would hope that they are providing insulation and heat taping to prevent freezing. If you are talking about the emergency hookups at operating plants, consider that simply draining the external piping can prevent ice plugs, just as most homeowners do with their outdoor yard faucets. Or consider the fire hydrants used in most cities, fires happen in winter, too.

Rive

Of course operating plants can handle a winter - they had some, and they are still operational.

I'm talking about Fukushima, the crippled plants and the equipment there.

Pictures about piping 'in the wild':
http://www.tepco.co.jp/en/news/11031.../111022_20.jpg
http://www.tepco.co.jp/en/news/11031.../111022_26.jpg
http://www.tepco.co.jp/en/news/11031.../111022_08.jpg

From here: http://www.tepco.co.jp/en/nu/fukushi...11022_02-e.pdf

I have some doubts.

NUCENG

I have doubts as well, but pretty small ones. In the outdoor pictures I see some hoses that probably will need to be insulated and or heated. Components in the buildings and tent shelters can be heated with space heaters. Some piping of chemicals may not be close to freezing (salt water is more susceptible to freezing as salinity is reduced.) Fluids can be heated. If a spent fuel pool has a small layer of ice, the water below probably isn't evaporating, and I doubt that winters could freeze more than 2o feet deep to where the fuel is located in spent fuel pools.

You asked a valid question, but it is not a show stopper.

Rive

The show will go on anyway, but if they are not already prepared then it can turn in some unexpected directions... That's what I'm worried about. And judged by the pictures, they are not thoroughly prepared.

We will see.

Shinjukusam

Well, and bear in mind that I've been to Fukushima in winter, it's not a very cold area.

from the Fukushima international exchange website:http://www.pref.fukushima.jp/kokusai...fukushima.html

Coastal Region
As the region is located at the southern most part of the northeastern region of Japan, it is fairly mild throughout the year. The average temperature for winter wavers between 2-3°C while temperatures rise up to mid 20s in the summer. Mostly dry & sunny winters with little snowfall, while in the summer sandy beaches prove to be the popular summer destination for all.

(although that last line will likely be revised)

zapperzero

http://cryptome.org/eyeball/daiichi-...chi-111211.htm
photo-reportage

Rive

Well, IMHO they should prepare for the worst, for this time - they are already failed with that once, with the tsunami...

NUCENG

As the Boy Scouts say, "Be Prepared!"

But please,Rive, take a deep breath and relax. There are many more threats that warrant your concern more than this. There is much less decay heat to remove today than in March. Even if something did freeze up, there is time margin to restore flow today that they didn't have then. If, and this is a big IF, they haven't already considered winterization, this is not even on the same continent as the failure to design for the tsunami. You raised a valid point, but you lose credibility if you overstate the issue. We don't even know if it has already been addressed or planned.

Rive

If what I said was like an overstatement, then: sorry. You are right, of course even worst case the result will be far from catastrophic.

But I want them to pass this second exam (proper handling of the events is like a second exam for them, IMHO, ?!) so I'm still worried, even if the consequences of a fail are not, nowhere in match with the original accident :-)

We will see.

nikkkom

Loss of gravity is (a) implausible and (b) wouldn't matter anyway, since all other human infrastructure would be destroyed by it, not only NPPs.

SBO and EDG failures are plausible failure modes.

nikkkom

Sorry, but it is not true. Many *existing* NPPs will suffer meltdowns in this case. By now I think we need to mandate that all new NPP must be designed, and most existing NPPs retrofitted with means to prevent that. *Passive* means: EDGs do not count.

If you mean, "was it possible at F1?" then I am interested in the answer too.

NUCENG

You proposed: "Do a mental exercise: imagine that all EDGs on all NPPs on the planet have vanished into thin air; then cut all power - put all NPPs into extended SBO." and call that plausible?

This is a technical forum. If your intent was simply to state that if an extended SBO could result in another accident, then you are correct. However, for such an event to occur, absent a similar design deficiency as the tsunami at Fukushima is very low risk. For it to occur at every plant on the planet simultaneously is a risk on the same order of probability as loss of gravity.

If you want to make your post topical, please explain how "EDGs vanish into thin air" and "cut all power" is probable at even one other plant unless there is another 1000 year external event. Then please explain why you think lessons learned from this accident won't make another accident even less likely.

I am not questioning your concerns or fears, but at least on this thread, let the anti-nuke hysteria be based on something more credible than your mental exercise appears to be.

rmattila

Another issue to take into consideration is the separation between "regular" EDGs and specific (usually air-cooled) SBO diesels fitted to some plants to enable certain vital safety functions even if all EDGs are lost. If they have sufficiently diversified power supply lines, they might provide some extra depth against severe accidents in station blackout situations. There seems to be a variety of opinions on how such dedicated SBO diesels should be treated in the post-Fukushima station blackout analyses.

nikkkom

The thought experiment wasn't meant to simulate a SBO over entire planet. That is not plausible. It was meant to construct an (implausible) situation in which every currently existing NPP is forced to go through real Fukushima event.

I am saying that I do not believe that almost every plant will survive. IOW: I don't believe in "stupid Japanese are to blame" theory.

nikkkom

OTOH, in winter uncovered SFPs have naturally better cooling :D

NUCENG

Neither do I, but the failure of TEPCO to incorporate new information about tsunami threats was a huge mistake that was a root cause of the accident.

It is not enough to come up with a "thought experiment" of extended SBO to condemn nuclear power in general. That "extended SBO" must be plausible and that takes more than imagining EDGs vanishing into thin air and loss of all power.

I reject your "thought experiment" unless you can show that there is a reason to believe the Fukushima scenario is plausible at other plants. This means you must identify a realistic set of external events and internal design vulnerabilities that can cause a similar result. And you must show that the lessons learned from Fukushima cannot or will not mitigate that vulnerability. Finally you must explain why the risks outweigh the benefits of nuclear power generation as those vulnerabilities are addressed.

If that burden can be met for any nuclear plant, then I, too, want that plant shutdown immediately and until until the vulnerabilities are corrected. If even one of these criteria can be met the burden should shift to the operators of the plant to show cause why they should be allowed to continue to operate pending corrective action.

This seems to put a huge burden on the person or organization that opposes nuclear power, but don't bother with the tired complaint that it is up to the nuclear industry to prove that it is safe to operate. "Safe" is an illusion and is not the issue. Nuclear power has risks and every plant that has been licensed has met the regulatory standards to show that the risk is low.

I reject your "thought experiment" because it is intellectually dishonest to apply a standard of 100% safe to nuclear power while tolerating the risks of tobacco, fossil plant emissions, automobiles, and the millions of other activities that do not meet that standard.