A third explosion in four days rocked the earthquake-damaged Fukushima Dai-ichi nuclear plant in northeast Japan early Tuesday, the country's nuclear safety agency said. The plant's owner, Tokyo Electric Power Co., said the explosion occurred near the suppression pool in the reactor's containment vessel. The pool was later found to have a defect.
Tokyo Electric Power said some employees of the power plant were temporarily evacuated following the blast. The incident follows two hydrogen explosions that have hit the plant as authorities struggle to prevent a catastrophic release of radiation in the tsunami-devastated region. The accidents have injured 15 workers and military personnel, and exposed up to 190 people to elevated radiation. International scientists have said there are serious dangers but not at the level of the 1986 blast in Chernobyl. (Read more Fukushima Dai-ichi stories.)