Tepco’s tank leaks blamed on seals, reassembly


The huge radioactive water leak discovered at a storage tank last week at the Fukushima No. 1 nuclear plant was likely caused by deteriorating rubber seams and distortions that emerged after the tank was reassembled, Tokyo Electric Power Co. says.

Tepco said Saturday that the temporary tank, which held water used to cool the melted fuel in three of the plant’s shattered reactors, was moved and reassembled after it began sinking two years ago amid subsidence at the site.

On Aug. 19, Tepco revealed that 300 tons of the tainted water had vanished from the tank, marking the fifth and worst leak there since the March 2011 mega-quake and tsunami triggered the man-made disaster.

All five of the temporary tanks involved in the leaks were collapsible and held together by rubber seals, meaning they were less durable than those with welded seams.

Tepco spokesman Noriyuki Imaizumi said the tank passed a water-tightness test and other safety requirements after it was reassembled, but that the leak might have started when the seals began deteriorating, leading to contortions in the tank.

Tepco has not pinpointed the source of the leak but is concerned that moving and rebuilding it contributed to the incident, rated Level 3 on the International Nuclear Event Scale.

In all, three of the temporary tanks have had to be dismantled and moved because of sunken foundations, the beleaguered utility said. The tanks were relocated in September 2011.

The water in the other two, which are also at risk of leaking, was put in other tanks Sunday.

Nuclear regulators have raised concerns about the flaws of rubber-seam tanks and are urging Tepco to switch to welded-seam tanks, which take longer to assemble and are more expensive.

Tepco said it believes the water went directly into the ground, but that some might have flowed into the Pacific via a rain gutter.

About one-third of the plant’s nearly 1,000 storage tanks are of the rubber-seal type.

Nuclear regulators who toured the crippled plant after the leak was reported declared Friday that the handling of water storage at the site was “sloppy.”

More than two years since the crisis began, Tepco is stumbling badly on the cleanup while the water threatens to spark another environmental disaster.

Calls are growing for outside experts to step in and take control of the operation.

  • mikethurgood

    It doesn’t really look as though TEPCO are paying proper attention to the finer details of their recovery work at Fukushima. If 300 tons of water had leaked away, 300 tons is near to 300 cubic metres – and this allegedly hadn’t previously been noticed?

    I must admit that using tanks made with rubber seals between the plates is curiously novel for such an important requirement as containing highly radioactive water, especially as they had been dismantled and reinstalled at a different location – with, for goodness sake, the same rubber seals???

    I won’t get any answer, of course, but are there any really professional engineers in TEPCO? I rather agree with the comment in the article that “calls are growing for outside experts to step n and take control of the operation”, irrespective of the expense.

    Why, of all countries, does Japan have to be so unconcerned about the appalling effect it is having on the credibility of the nuclear power industry across the world? Is there no longer any pride in achieving and maintaining credibility, internationally?

  • originalone

    I’m looking at this from across the Pacific Ocean, but I have to ask: “just who is running this show”? How in the world can any company, regardless of size/influence, get away with doing what is being done at this site? Is there no shame to this incompetent performance? I’ve always thought the Japanese were above cutting corners, took pride in the quality of their work, not taking a page from the greed first, the health of the people don’t mater, book.

  • I am flabbergasted at the fact that they are using temporary and improperly sealed tanks to hold such toxic materials. I understand the need to use “popup” tanks in the face of an emergency but now, years later, the materials should have been transferred to a tank manufactured to house such items.