[gus_massa]

I don't know the exact model of this plant, but I read about the Fukushima plant in Japan.

The Fukushima plants had control rods, they are inserted in the reactor to stop almost entirely the uranium fission. They were inserted automatically, so most of the heat creation was stopped in a short time.

The problem is that the fission creates some unstable atoms, that continue to decay mostly in a few days and create additional heat. The refrigeration must have continued for some days, but they couldn't because they lost all the alternative electricity sources. :(

So the reactor overheated and they must release steam and use sea water to cool it and things like that. Those measures released some radioactivity to the environment.

After a few days, the only active nuclear reactions are the spontaneous fission of uranium and the decay of the other radioactive intermediate products. This created very few heat and they wouldn't need any active refrigeration. They were able to put the other reactors in Fukushima in this state, so they didn't create any problem.

The power plant in California is closed since one year, so it's almost sure in a stable state that doesn't create too much heat, so the probability of a nuclear disaster is very low.

[akiselev]

You missed the main part of the disaster where the cores of reactors 1, 2, and 3 melted down (fuel rods melting and collecting in a pool at the bottom of the core) after the cooling failed. This led to hydrogen explosions, the boiling away of most of the coolant, and some problems with the waste fuel pool (also lost cooling shortly after the meltdown I think).

Also it wasn't "after a few days." The site wasn't stable until almost nine months later (December, 2011).

[hga]

The issues here is what is your worst case when you loose your cooling. After Three Mile Island and Fukushima we have some answers for their respective designs: pressurized water reactors which have everything "hot" inside the classic dome also keep enough of that hot stuff in it, boiling water reactors that have things spread out in a rather complicated design don't.

And the insane Chernobyl design....

[gus_massa]

Ok, this is a safer design. Anyway, my point is that loosing the cooling system of an active nuclear plant is much worse than loosing the cooling system of the shutdown nuclear plant (but don't try that at home). So it's not necessary to rush to dismantle the nuclear material, because of the fear of a tsunami. Those material should be handled properly.