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In this photo provided by Nuclear Regulation Authority (NRA), NRA commissioners inspect storage tanks used to contain radioactive water at the Fukushima Dai-ichi nuclear power plant, operated by Tokyo Electric Power Co. (TEPCO), in Okuma in Fukushima prefecture, northern Japan, Friday, Aug. 23, 2013. Deep beneath Fukushima's crippled nuclear power station a massive underground reservoir of contaminated water that began spilling from the plant's reactors after the 2011 earthquake and tsunami has been creeping slowly toward the sea. Now, 2 1/2 years later, experts fear it is about to reach the Pacific and greatly worsen what is fast becoming a new crisis at Fukushima: the inability to contain vast quantities of radioactive water. (AP Photo/Nuclear Regulation Authority)

Associated Press,

Seam possible cause of Japan nuke plant tank leak

  • Article by: MARI YAMAGUCHI
  • Associated Press
  • August 24, 2013 - 10:35 AM

TOKYO — The operator of Japan's crippled nuclear plant said Saturday that deteriorated seams and a possible contortion of a reassembled storage tank might have caused a massive contaminated water leak that has triggered fears over the plant's radioactive water management.

Tokyo Electric Power Co. said that after the foundation of the tank, which was storing radioactive water, partially collapsed two years ago, it was moved and reassembled. A 300-ton water leak from the tank was discovered Monday.

The massive leak was the fifth and worst from a Fukushima Dai-ichi tank since the plant suffered triple meltdowns after the massive earthquake and tsunami in 2011. All five of the plant's tanks are collapsible and are seamed with rubber seals.

TEPCO spokesman Noriyuki Imaizumi said the tank passed a water-tightness test and other safety requirements after being reassembled. The leak might have started when rubber seals degenerated, failing to cushion the tank's possible contortion, he said, adding that the company was further investigating the cause.

Nuclear regulatory officials have raised concerns over a design flaw of the rubber seam tanks and urged a switch to more durable welded-seam tanks.

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

About one-third of the plant's 1,000 tanks storing contaminated water use the same design. The water had been used to cool the wrecked reactors.

The latest leak was another example of how TEPCO has repeatedly failed to acknowledge problems it could have foreseen and acted on to mitigate before they got out of control. The tank problem also compounds TEPCO's ongoing battle with other radioactive water leaks from elsewhere in the plant that have already escaped into the ocean.

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