Partial Meltdowns Led to Hydrogen Explosions at Fukushima Nuclear Power Plant

Just after 6 AM local time on Tuesday in Japan, a sound like an explosion was heard near the suppression pool of reactor No. 2 at the stricken Fukushima Daiichi nuclear power plant. This followed an explosion March 11 that ripped the roof off reactor No. 1 and another at reactor No. 3 on March 14 that injured 11 workers. The culprit in all three cases is likely a build-up of explosive hydrogen gas—as occurred at Three Mile Island in the U.S. in 1979 as a result of the meltdown there—caused by nuclear fuel rods experiencing extremely high temperatures stripping the hydrogen out of the plant's steam.