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They're saying
The nuclear fuel in three of the reactors at the Fukushima Dai-Ichi nuclear plant has melted through the base of the pressure vessels and is pooling in the outer containment vessels, according to a report by the Japanese government.


Melt-downs of the fuel in the No. 2 and No. 3 reactors followed over the following days with the molten fuel collecting at the bottom of the pressure vessels before burning through and into the external steel containment vessels.

The fuel appears to be stable at present as it is being cooled by water pumped into the vessels, although it will complicate the emergency recovery plan put forward by the government.

The problem with this is that concrete decays at a lower temperature than that at which the steel of the containment vessel melts. So "the fuel is pooling in the outer vessels but appears to be stable" seems reassiring until it doesn't.

If one believes that the people in charge know more than they are letting on and are "managing the information flow" this might mean that they know the corium will also breach the outer containment vessel, or that it has already done so.

If the melt is able to burn through the concrete containment it must be above 1000C - what are the odds that the melt will cool down enough before reaching the water table?

And, just a hundred meters or so from the sea, how deep is the water table?

Economics is politics by other means

by Migeru (migeru at eurotrib dot com) on Sun Jun 12th, 2011 at 08:01:40 AM EST
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The one point I don't get is "the external steel containment vessels". Aren't the pressure vessels steel and the containment vessel concrete? Or does the containment vessel have a steel layer?

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Sun Jun 12th, 2011 at 10:10:56 AM EST
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Maybe they mean "steel containment" external to the "zirconium casing" of the fuel rods which we were being told was melting or burning back in March...

Economics is politics by other means
by Migeru (migeru at eurotrib dot com) on Sun Jun 12th, 2011 at 10:53:19 AM EST
[ Parent ]