The bomb, dropped by American forces during the war, is about half a mile from reactors Numbers 1 and 4, which were damaged in the 9.0-Richter-Scale quake and subsequent tsunami. Fukushima was an airbase during the war and was a regular target of a U.S. bombing campaign that culminated in the dropping of atomic weapons on Hiroshima and Nagasaki. The recently discovered bomb, which its 33 inches long and 6 inches in diameter, is not thought to be a nuclear one, officials said.

Recovery continues at the damaged nuclear plant six years after the twin disasters. The latest initiatives have been to examine underwater area below the reactors, to determine the extent of nuclear waste still being emitted.