Operator of Japan's crippled nuclear plant cites seam problem as possible cause of tank leak

TOKYO - The operator of Japan's crippled nuclear plant says deteriorated seams and a possible contortion of a tank might have caused a recent massive contaminated water leak.

Tokyo Electric Power Co. said Saturday that the tank was reassembled after being relocated from a site where its foundation had partially collapsed. The tank's 300-ton leak was found Monday.

TEPCO said the tank passed a water-tightness test after being reassembled. The leak might have started when rubber seals degenerated, failing to cushion the tank's possible contortion.

TEPCO said that the leaked water seeped mostly underground, but that some might have escaped into the Pacific.

The plant suffered multiple meltdowns following Japan's massive earthquake and tsunami in 2011. Radioactive water from elsewhere in the plant has also been leaking into the ocean.