Roughly 20 or more of the water tanks holding radioactively contaminated water at the Fukushima No. 1 Nuclear Power Plant are secondhand, it has been learned — a fact that plant owner Tokyo Electric Power Co. (TEPCO) had not previously disclosed.
In August 2013, highly radioactive water was found leaking from one of the plant’s tanks. A TEPCO representative refused to comment on whether that tank was one of the used ones.
The secondhand tanks and the tank that leaked are all types assembled by bolting steel pieces together, known as “flange” models. TEPCO has said flange tanks can be used for five years. When questioned by Mainichi Shimbun, a representative for the utility commented, “We do not believe that used tanks have a shorter usable lifespan.”
However, an inside source with a Tokyo company that supplied TEPCO with the tanks told the Mainichi, “We don’t guarantee the tanks for five years as a company, and they are not made to be completely leak-proof in the first place.”
According to the source, TEPCO ordered tanks from the company in Tokyo’s Chuo Ward after the March 2011 Great East Japan Earthquake to store contaminated water, but since it would take too much time to make new ones, in around May 2011, the manufacturer supplied TEPCO with 20 to 30 used flange tanks — mud-storage tanks that it had been renting out to businesses such as construction firms.
Multiple private investigation firms have said that the tank supplier reported high profits for June 2011 as the nuclear disaster created heavy demand for its water tanks and enabled it to sell off “depreciated” tanks. The reference to the tanks as “depreciated” is believed to indicate that a considerable amount of time had passed since their manufacturing date. The flange tanks provided by the company after this point are thought to have been new ones.
In the August 2013 incident at the Fukushima plant, around 300 tons of contaminated water was found to have leaked from a flange tank. Criticism grew over the fact that this tank had been taken apart, reassembled and moved on the plant grounds before the leak occurred. At a news conference around this time TEPCO said that this tank and two others had been relocated, but it made no mention of secondhand tanks.
Since October 2012, the company has been creating and supplying TEPCO with welded tanks that are more resistant to leaks, but most of the flange tanks, including the secondhand ones, are still being used at the Fukushima plant.
It has also been learned from an inside source at the manufacturer that even after TEPCO started to use welded storage tanks, it continued to build new flange tanks for around a year. The source suggests that this was to save money, as it was not until September 2013 that the government decided to apply public funds to the tanks’ purchase. According to the source, welded tanks cost anywhere from two to three times as much as flange tanks.
TEPCO reports that as of April 22 this year there were 332 flange tanks and 552 welded tanks at the Fukushima plant. The utility plans to start replacing the flange tanks with welded tanks this coming September to prevent more leaks.