[americanophile]

Well, apparently there are Water cooled reactors, Liquid metal cooled reactors, Sodium-cooled fast reactors, Lead-cooled fast reactors, Gas cooled reactors, Molten Salt Reactors, etc. I don’t know what kind of reactor is at issue in Japan and what coolant has been delivered.

[The_Victor]

Japan uses the same inherently stable reactor design that the US uses: water coolant. The water also drives the reaction by slowing neutrinos and reflecting them back into the reaction. Without the water in the reactor core the reaction dies out.