[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.

[HereInTheHeartland]

It’s a battle for control it sounds like:

http://www.reuters.com/article/2011/03/11/us-japan-quake-reactor-idUSTRE72A2NR20110311