Japan Earthquake 2011: Nuclear Battle May Take Weeks. Three reactors have had at least partial meltdowns, but an even greater danger has emerged.

Japanese and U.S. concerns were increasingly focusing on the pools used to store spent nuclear fuel: Some of the pools are dry or nearly empty and the rods could heat up and spew radiation.

nuclear fuel rods in two reactors were only about half covered with water, and in a third they were also not completely submerged.

If the fuel is not fully covered, rising temperatures and pressure will increase the chances of complete meltdowns that would release much larger amounts of radioactive material than the failing plant has emitted so far.

Japan Earthquake 2011: Nuclear Battle May Take Weeks, Says U.S.