Monday, June 6, 2011

Arnie Gundersen: "On-and-Off Recriticality Possible in Reactor 3"

I was listening the podcast of the interview Arnie Gundersen gave to Chris Martenson the other day (in order to translate into Japanese) and noticed something I had missed when I skimmed through the transcript for my post.

Gundersen is saying that 10% of the fuel core of the Reactor 3 may be repeating a re-criticality, on and off:

"Unit 3 may not have melted through and that means that some of the fuel certainly is lying on the bottom, but it may not have melted through and some of the fuel may still look like fuel, although it is certainly brittle. And it's possible that when the fuel is in that configuration that you can get a re-criticality. It's also possible in any of the fuel pools, one, two, three, and four pools, that you could get a criticality, as well. So there’s been frequent enough high iodine indications to lead me to believe that either one of the four fuel pools or the Unit 3 reactor is in fact, every once in a while starting itself up and then it gets to a point where it gets so hot that it shuts itself down and it kind of cycles. It kind of breathes, if you will.

"I think it's a relatively significant amount – maybe a tenth of the nuclear reactor core starts back up and shuts back down and starts back up and shuts back down. And that’s an extra heat load; you are not prepared to get rid of one tenth of a nuclear reactor’s heat by pumping water in the top."

Hiroaki Koide of Kyoto University suspected an on-and-off recriticality in the Reactor 1 back in early April when TEPCO announced, supposedly erroneously, chlorine-38 was detected. Dr. Tetsuo Matsui of Tokyo University suspected recriticality in the Reactor 2 and/or the Reactor 4 Spent Fuel Pool. Gundersen suspects an on-and-off recriticality in the Reactor 3 (or any of the Spent Fuel Pools).

Below is the chart of iodine-131 detection at the Federal Office of Radiation Protection in Germany, plotting the CTBTO station data from around the world. Station 38 is Takasaki, Gunma Prefecture in Japan, 218 kilometers (135 miles) from Fukushima I Nuclear Power Plant. I always thought it was rather peculiar that there seemed to be periodic spikes in the amount of iodine-131 (also of cesium-137 but to a lesser degree) followed by a relatively calm, steady decline.

Could these spikes indicate what Gundersen is talking about? On-and-off recriticality?


Anonymous said...

Take a look at the temperature chart for reactor 3.

The rpv flange reading appears to follow a similar pattern to the iodine releases, though it might be any of them. This may be some small evidence that it's reactor 3 that may be 'turning on'.

culture of insanity said...

Weird. The pdf data does not fit with the other data shown to the public:

But indeed the Iodine spikes in the PDF do match for the time about 17-19.4. (First temperature spike, followed by a Iodine 131 spike and then the massive spike at 4. May in temperature is followed immediately by several spikes in Iodine 131.

Also interesting is this figure (radiation in #1 reactor)
In which these spikes in radiation are also mirrored exactly (!) by Iodine 131 spikes (including the "gap" around 26/27 May)

arevamirpal::laprimavera said...

@culture of insanity, numbers for radiation in Reactor 1 are not to be trusted, apparently. The official "plant parameters" sheet says the monitoring equipment is broken. But since that's what TEPCO and NISA say...

culture of insanity said...

I tried to visualize what I just wrote. I linked the graph in - the red bars are the correlations...

arevamirpal::laprimavera said...

Sehr interessant...

Secular said...

Could an external atmospheric influence be the cause of the spikes/re-criticality?
(I'm very very slightly re-assured that the overall tend is down)

Anonymous said...

Aren't control rods in place in reactor 3? I don't see how non-failed fuel could restart if that is the case. I have never seen a discussion of control rods failing due to decay heat, though of course that doesn't mean it couldn't (or didn't) happen.

Anonymous said...

From What I saw in the Hi-Res Pictures, there are no control rods left and this is now a molten Mass that is going in and out of fusion. This is going to be continue for quite a while. I believe #3 was using the MOX Fuel, containing Plutonium.

Anonymous said...

This link,

from culture of insanity's blogsite certainly shows how dynamic this meltdown product is. If it were not evolving you would see horizontal lines for equilibrium temperatures.

@ secular,

rest assured that external atmospheric influences are not affecting these demons.

@ anonymous 9:22,

do you have pictures of RPV interior, or even underside of RPV exterior?

Even going by temperatures that TEPCO has admitted to, there should be no intact control rods. None.

Anonymous said...

Atmospheric influences could indeed play a role in measuring the Iodine 131 as it is measured in quite a distance to the plant (several tens of kilometers IIRC). Winds turning direction could therefore change the payload of radioactive particles arriving from the plant to the station. So in theory that could be, a correlation with the wind direction would have to be made to assess that.

The control rods are as I understand it inserted from above into the rack of fuel rods. Probably the control rods are still there, but they are useless because the fuel has broken down and collected at the bottom (or even outside) the RPV, so the control rods if they still exist are hanging in the radiactive air inside the RPV.


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