Japan Earthquake: nuclear plants

mscharisma

Thank you. And it's actually funny that the article is from March 18 and very well makes my point: the scale changes.

Being on the brink then meant that cooling was imperative since "otherwise, a meltdown of the core could occur or, respectively, continue in the reactors."
"Die Kühlung der Reaktoren und der Abklingbecken der Reaktoren 1 bis 4 ist entscheidend. In den Reaktoren könnte sonst eine Kernschmelze einsetzen beziehungsweise weiterlaufen."
For Unit 1, we're past that and on a new brink, I suppose.

default.user

Salad ideas:

The corium is very quickly a firm skin.
At this time, borated water is not able to do its work.
The gescmolzenen pellets in the corium are critical and can tear the skin.
Borated water penetrates and prevents the critical situation.
Neutrons are absorbed. The skin will close again and the result is again criticality. The skin tears open again and borated water penetrates. Neutrons are absorbed and prevented the criticality.
The theater goes on until all the fission products are exhausted. The corium remains hot until the fission products are exhausted.
So far so good.
As long as not burst the vessels, one can talk from a funny cat and mouse game.

GJBRKS

http://english.kyodonews.jp/news/2011/05/91196.html

Has it reached cold shutdown yet ?

(EDIT : yes it has ... http://search.japantimes.co.jp/cgi-b...0110516a5.html )

That's kinda what you see ... One report speaks of 2 hours trouble on a Sunday , the other says the problem had been found Saturday starting at 4:30 p.m. .......Tsk Tsk

default.user

I forgot to mention:

While the skin breaks and water comes with the liquid part of the corium in connection arises suddenly steam. This steam can be derived as barrier-free. Otherwise there is a steam explosion. In addition, the highly radioactive steam.

mscharisma

The spin and hence the correct/best interpretation of the scientific data (by you guys, of course, not me) is what's so important.

It's maybe just natural that a progression from bad to even worse and yet worse is difficult to accurately put into perspective, but at the same time I'm concerned about deliberate minimization by the plant operator, government, and mass media and the consequences for the affected population. For those of us Europeans and Russians who are old enough to remember the Chernobyl aftermath, very similar to the Fukushima situation, the info for the public started with "don't worry about it," went to "well, it's bad but not dangerous," to "yeah, it's worse than thought, but not deadly." (obviously paraphrased)

If the risk from Units 1-3, at a minimum, is the continued contamination of ground- and seawater through radioactive water leakage, I hope every layperson makes a decent effort to understand what's going on and what the consequences for him/her may be.

Many thanks to you knowledgeable folks and experts who put so much effort into collecting and interpreting the scientific data as it becomes available. Even if we laypersons may not comprehend the highly technical stuff, we at least don't have to rely on the spin in press releases and mass media reports because you instead provide us with -at a minimum- educated guesses what's going on and we can then guess what it all means for each individual in his/her respective geographic location.

etudiant

Wow! That is a serious screw up.

To have sea water enter the reactor means that they really gummed up the shutdown operations.
Under normal circumstances, heads would roll. Now, it's just a problem in a plant that is dead anyways.
Still does not speak well for the competence of the operation.

KJones

This site is complaining that Chubu delayed 20 hours before making an announcement about the seawater: http://criticality.org/2011/05/hamao...rway-problems/

Uagrepus

Yes, in your pictures it already looks like the broken pipe *after* Unit 4 explosion:

etudiant

There is no doubt that the leadership , both corporate as well as national, is treading a fine line, trying to minimize concern without doing real violence to the truth. So any public statement should be read in the context that it aims to reassure first, even before it informs.
The problem this creates, at least imo, is that it does not adequately take into account the extra vulnerabilities of children, who play in the dirt a lot and who are more susceptible to contamination damage.
Of course, the damage done to everybody, children included, from a panic or mass evacuation would be even worse, so the same logic applies, reassure and tell the unavoidable minimum. Not an easy balancing act.

AntonL

Sea water in Hamaoka cooling system

If sea water is detected in the cooling loop of the reactor, leads me to believe that there is a problem in the heat exchanger of the cooling system. In the closed loop you have reactor water which exchanges its heat to the sea water. If there is a crack in the heat exchanger sea water can be sucked into the reactor circuit, either due to Bernoulli effect at high flow rates or the system was at under pressure as steam condensed to water at the cooling stage and fresh water was not replenished fast enough.

GJBRKS

Would such a system have 3 cooling loops , another heat exchange at the reactor ?

If not then I guess contamination of reactor water into the environment can not be ruled out.

(I'm not saying it would be radioactive , just that it would have breached containment)

SteveElbows

I dont think they had stated that the Hamaoka closure was to be permanent. I think it was supposed to remain shut whilst they came up with new measures against things like tsunami. Of course its possible that it would never reopen if such measures could not be completed or the politics remained very difficult, but thats not how they wanted to present the story at this time.

turi

A PDF about unit 1 shows two floor plans. I don't know if they show anything not known here yet:
http://www.meti.go.jp/press/2011/05/...10515001-5.pdf
(I believe it's about the staircase in the north-west where they have seen water accumulating).

Caniche

That was just too easy,do another one cos I can't quite believe Tepco are that dumb. Then again on reflection ,no need.

jlduh

If they say now truth, the only explanation is see is that... they were lying before! Well, we can understand it, why panicking people recognizing the reactor just melted in the first 16 hours?

Is their new assessment not far from the old original document assessing what would happen in a timely manner in case of severe accident in a BWR mark I reactor?



By the way, have these studes already been posted here?

1) VERY INTERESTING STUFF IN IT, details and schematics including failure modes

THE IMPACT OF BWR MK I PRIMARY CONTAINMENT FAILURE
DYNAMICS ON SECONDARY CONTAINMENT INTEGRITY


http://www.osti.gov/bridge/servlets/...Hq/5835351.pdf



2) IDENTIFICATION AND ASSESSMENT OF BWR IN-VESSEL
SEVERE ACCIDENT MITIGATION STRATEGIES

http://www.iaea.org/inis/collection/...2/24072657.pdf

jlduh

Yep, i remember well also...

It will be very interesting to re-read this thread from scratch after some time.

bytepirate

i still don't buy that. there were more than 24 hours between the explosions of #3 and #4...
and we have this information ('tepco says...') only second hand. the same quality of information as we had before for a contradictory explanation (explosion in #4 blowed away a gate and reflooded the SFP).
let's wait and see ;-)

something else:
as i am not able to see the 'live feed', can anyone who can see it confirm, that everything looks normal?
the webcam shows something, that might be smoke: http://pointscope01.jp/data/f1np/f1n...0516060032.jpg (its the same pic, that the webcam shows right now)