At the Fukushima nuclear power plants, fears of another explosion remain high.

FORBES: Dispatch From Tokyo: Living Through The Worst Crisis Since World War II

An explosion in the middle of the night at the Chernobyl nuclear power plant in Ukraine tore off the plant's roof and sent radiation over much of Europe.

NPR: Ukraine Remembers Chernobyl Nuclear Disaster

Nuclear plant operators are battling to prevent meltdowns at three reactors, and Chief Cabinet Secretary Yukio Edano warned Sunday that a hydrogen explosion could occur at Unit 3 of the Fukushima No.1 nuclear power station.

FORBES: For An Accessible Explanation Of Japan's Nuclear Crisis, Watch 'The West Wing'