03-13-2011, 09:56 PM
Lux Interior wrote:
[quote=Paul F.]
filled with neutron absorbing, reaction killing, chemicals (halfnium and boron, I think... but I admit my nuclear physics is barely above layman level, and more than a little rusty).
This is another misconception - that the reactor is out of control. The reactor(s) are shutdown. They have been since the quake hit. The problem isn't fission. It's decay heat. Even after you stop the fission chain reaction, the core continues to produce heat from the decay of the fission products. This is about 7% of the operating power before shutdown and then it decays from there.
About 40 MW of heat to remove from unit one assuming it was going at full power. Not a lot, but enough heat to melt the fuel unless adequate cooling is provided.
I appreciate the correction..
It's my understanding that IF the fuel rods melt completely, that the resulting "puddle" could begin fissioning again, at a reduced rate.
So whatever is below the reactor vessel is another step to keep it from fissioning under that sort of "worst case" - which neither of these reactors seems to be close to.
If the residual heat and decay heat are removed, that's no longer a possibility (if it ever was with this type of fuel design...)
From what I've read about this design.. there is an outer building (where the hydrogen collected and exploded), an outer containment shell of reinforced concrete and steel, which is INTACT, and inside THAT, the 6" thick stainless steel reactor pressure vessel, which is also intact.