Japan Earthquake: nuclear plants

gmax137

Where did you get that idea?

james14

I realize this is speculation on my part, but all of these latest statements including the one about 10,000 TBq per hour for a number of hours really seems to point to them knowing quite a bit more than they are letting on.

|Fred

Considering that at d + almost 30 , they aren't any closer to restore cooling , if anything situation is worse , containment is not really containing , what option do they have ? They can't let it bleed out for ever ...

gmax137

If the intake structure was damaged enough to compromise the service water system (whatever its name is in a BWR), then none of the cooling systems would be available, right? Regardless of whether the diesels were running or not? I don't have a clear idea of the BWR systems, and how the steam-driven (RCIC?) is supposed to work in the long term. Can you maintain cooling that way (steam driven pumps) in the long-term, or do you necessarily need to cool the water in the torus, removing the heat via the service water system? Does anyone have a link to a good description of these systems?

tsutsuji

The report is probably the following one : http://www.rri.kyoto-u.ac.jp/NSRG/se...port11-4-4.pdf

http://www.rri.kyoto-u.ac.jp/NSRG (Nuclear Safety Research Group at Research Reactor Institute, Kyoto University) provides a link to http://hamanora.blog.ocn.ne.jp/kaiin02/ where there is more to read.

TCups

An interesting question, indeed. Posited another way: If the emergency efforts to cool the reactor cores are (and it would seem, can only be) a temporary solution as long as the coolant (water) is not contained in a closed system,

Then only three alternatives exist:

1) Continue to spill contaminated water and slowly (relatively) contaminate the ground water and ocean while temporizing. (possibly, to allow time to deal with the spent fuel in the SFPs?), or

2) Somehow devise a stable, permanent system to contain, decontaminate and if possible, recirculate the water being used for cooling the cores (unlikely), or

3) Prepare to let the cores melt and deal with the consequences.

Is there another option I am missing? If not, then option (3), it seems, is most likely the "not if, but when" final event in the Fukushima disaster sequence.

Which begs the question: What might be done while temporizing with the current efforts to cool the cores to mitigate the ultimate consequences of one or more melted reactor cores with loss of the primary containment? If the answer to that question is "nothing effective", then, is option (1) with ongoing contamination by un-contained, highly contaminated water for as long as humanly possible worse than option (3)?

I don't know.

bytepirate

a good overview, but:
"Recriticality in Unit 2 ?
(according to soil samples,
might explain radioactivity spike on march 16)"

is there *any* evidence for a recriticality in #2?
the spike on march 16th could be much better explained by (undetected??) melting/burning fuel in #4 SFP (imho):
there was an explosion before:
http://www.tepco.co.jp/en/press/corp...1031504-e.html
and a fire afterwards:
http://www.tepco.co.jp/en/press/corp...1031606-e.html
and in the meantime, the (then uncooled) fuel took a nap?

AntonL

a core melt might be a cleaner solution than a continues feed and bleed, only if it can be guaranteed that the molten core does not go critical, and to prevent a steam explosion the dry well must dry which it is not.

biscuitcheese

I dont know what the sea depths are near the plant, or what kind of logistic/financial nightmare it may be, but why couldnt they hire or buy a bunch of oil tankers to sit off the coast to facilitate easier siphoning of contaminated water from the plant to the oil tankers as an expendible temporary storage solution for the contaminated water?

It seems to be better than purposely dumping what is already collected/contained radioactive water into the ocean because 'they had no choice'. If it was an uncontrollable leak thats one thing, but if their problem is with storage (and it seems to be the case earlier with the purposeful dumping), then there are obvious solutions that can be had like hiring/buying oil tankers to store the water.

Pheesh

Well it's now basically official, I guess they just felt like skipping 6!
http://www3.nhk.or.jp/daily/english/12_05.html

biscuitcheese

It baffles the mind how many so called 'experts' were on the news early in this disaster, who were adamant that the still developing situation could not possibly be worse than the TMI incident and that a disaster rating above 4 was impossible.

It seemed so obvious right from the very start the accident was worst than TMI because (1) there was reportedly a hydrogen explosion which for all intents and purposes can likely only occur if fuel rods were overheating leading to thermolysis of water catalysed with the zirc-water reaction to generate the hydrogen in the first place, and (2) the military subsequently detected I and Cs radioisotopes off the coast that obviously came from the reactor likely due to pressure releast from primary containment. Ultimately though, the facts have already demonstrated long ago that core overheating happened (likely with fuel cladding melting also since they didnt get cooling in there for a long time) and also that radioactive elements were already released into the atmosphere thus proven very early to be worse than TMI since TMI had fuel melting but no substantial amount of radioisotopes were released into the atmosphere and that there was no indications of breach in containment (not even the outer containment) for which was certainly not the case in the fukushima incident.

bytepirate

maybe they need a feynman (or any other brilliant mind, preferred alive) to come up with an unexpected fourth solution.
something like:
fill up the RPV with copper pellets, then pour in some radiator sealant (i have heard pepper and eggs are working), then cool the thing from the outside.

this is not a serious suggestion, but maybe the final solution will be something like that: unexpected, ridiculous - and working.

83729780

I honestly think they're still considering the giant cloth. It's been mentioned twice in Kyodo news reports.

Borek

Amount of heat evolving should be getting down, even if there are short criticalities. Once the power gets down they can stop cooling. But I doubt there is much that can be done earlier.

StrangeBeauty

Pardon if this is a repost: They've issued corrections to a number of released readings/info including pressure readings for RPVs #1 and #3:

http://www.nisa.meti.go.jp/english/f...20110411-3.pdf

[Edit]: There appears to be some new data for #3

shogun338

A fire broke out at Japan's crippled Fukushima Daiichi nuclear power plant, operator Tokyo Electric and Power (TEPCO) said on Tuesday, although flames and smoke were no longer visible. http://www.reuters.com/article/2011/...7FB1YD20110411

shogun338

Magnitude 6.6 - EASTERN HONSHU, JAPAN
2011 April 11 08:16:13 UTC http://earthquake.usgs.gov/earthquak...11/usc0002n9v/