Japan Earthquake: nuclear plants

tadjik

Apparently, whatever phenomena increases pressure in reactor 1, it seems progressive.
http://www.ic.unicamp.br/~stolfi/EXP...t-un1-full.png
Any hope this could just be some H2O vapor ?

And (if the question has not been raised yet) : 7 atm is a very high pressure, I thought the desin was for 4 atm ... why inject nitrogen under such circumstances ?

georgiworld

And here is further confirmation of your hypothesis. Nice job.
http://english.kyodonews.jp/news/2011/04/83613.html

Astronuc

Pressure would increase if the temperature of the gas increased. Nitrogen is there to provide for an inert, non-combustible environment. Of course, if there is a leak, then the nitrogen leaks as well.

Well, the design pressure is greater than 4 atm, but the operating limit would be specified at 4 atm to ensure that the containment had sufficient margin to failure. Theoretically, the concrete the steel liner should hold to about 7 atm, although the concrete might start cracking (leaking).

Leak-before-break is a typical approach to designing containment systems.

TCups

Well, it sounds like both news stories arise from reporting of the same conference, so it isn't independent "confirmation". And while it is interesting to think it may be something like what actually happened, I might characterize what was reported as "evidence for" rather than "confirmation of" the earlier hypothesis.

tadjik

OK, I understand for nitrogen. Thanks.

But the source gives temperature slowly going down; of course, they can think the data are wrong but it seems to me the 2 measures are "coherent" both in time and between them.
On the other hand, it does not exclude increase elsewhere in the system, of course.

|Fred

http://english.kyodonews.jp/news/2011/04/83613.html

=> in which way to you find it confirms anything?

edit: which

georgiworld

I may be mistaken in reading between the lines but as I read the article the managers of the disaster are attempting to prevent a repeat of what happened in Reactor3

According to the article "Nishiyama said past hydrogen explosions have likely occurred due to hydrogen accumulation caused by the reaction of melted fuel rods' zirconium with steam from the coolant water".

It also states that
"The utility has been pouring massive amounts of water into the reactors and their spent nuclear fuel pools as a stopgap measure to cool them down. But the measure is causing ''side effects,'' such as the detection of contaminated water in various parts of the nuclear complex and some leakage into the sea."

TCups points out "That big old steel reactor vessel sets on a pedestal like a long, skinny boiled egg. It is made of heavy steel, and it is full of water and one of the densest things I know of -- uranium.

Furthermore he states

"If the lateral acceleration forces exceed the design parameters, the pressure vessel risks becoming the upside down clanger in a giant bell shaking at about a 9 on the Richter scale."

The key vulnerable structure if that happens is the high pressure steam outlet pipe. If that cracks or leaks, then you have high pressure steam and shortly thereafter, hydrogen in the primary containment"

Astronuc

One can find there assessment reported in the NY Times here:

http://djysrv.blogspot.com/2011/04/n...fukushima.html

Giordano

Hope this is not a stupid comment...

7 atm, isn't that the reading inside of the RPV!? And I thought the operating pressure in the RPV is something like 10 times that!?

|Fred

Thank you.
ps: I'm i the only one with the google doc linked in the article displaying upside down?

Astronuc

If there is ample communication between the RPV and containment, then the pressure is more or less equal. The RPV is designed to handle much higher pressures (operational ~ 72 atm, but should withstand much higher) than containment (~ operating limit of 4 atm). The RPV is afterall a 'pressure vessel', and containment is only a low pressure container.

Astronuc

No - it's copied upside. Just print or flip the pages 180 degrees.

razzz

Firework Colorants

Attached Thumbnails

 

Giordano

Has anyone seen an estimate of how much total radioactive material has leaked (or still is leaking!?) or been dumped into the sea? I suppose most interesting is the amount of Cs-137.

Maybe someone here would like to maka a personal estimate?

The ocean is vast but not infinite...

bytepirate

new nuclide analysis

a lot of te-129m, but *no* te-129.

any explanation for that?

Giordano

http://www.tepco.co.jp/en/press/corp...1040613-e.html
"Injection of nitrogen to reactor containment vessel of Fukushima Daiichi Nuclear Power Station Unit 1"

(with schematics)

Astronuc

It's difficult to say at this point, because the source term (how much fuel has failed) is not well known. And there are 4 units with various degrees of damage.


As for fuel release, it would be useful to find out if there are any detections of:
Nd isotopes, and Ce¹⁴⁴, Zr⁹⁵, Ru¹⁰³, Ru¹⁰⁶, Ba¹⁴⁰, Eu¹⁵⁴ in addition to the volatile Cs isotopes, which are gamma emitters. Other than the Cs which can easily get out of the fuel because of low melting temperatures and solubility, the others are harder to get out and therefore their presence in the environment would support loss of fuel from damaged/breached fuel rods.