A series of leaks from underground storage pits in the compound of the stricken Fukushima No. 1 nuclear power plant forced Tokyo Electric Power Co. on April 16 to start transferring radioactive water from the No. 2 underground storage pool to tanks on the ground. This operation underlines the fact that the nuclear crisis at the power plant is far from over despite then Prime Minister Yoshihiko Noda’s Dec. 16, 2011, declaration that the stricken reactors at Fukushima No. 1 have entered “a state of cold shutdown” and that the nuclear crisis has “been resolved”(Shusoku ni itatta.)

Tepco has seven underground storage pools in the Fukushima No. 1 compound. Leaks have been confirmed in the Nos. 1 to 3 underground storage pools. It is estimated that up to 120 tons of contaminated water leaked from the No. 2 pool alone.

Tepco plans to finish transferring a total of 23,000 tons of tainted water from those three pools and a fourth pool to aboveground tanks, hopefully by the end of June once additional tanks are constructed.

The seven underground pools can together store 58,000 tons of water. Tepco thought that the three-layer protective waterproof sheets lining the pools would make them watertight, but leaks were detected March 5. It is regrettable that Tepco failed to pay attention to the simple fact that waterproof sheets can easily tear, especially along the seams. Once again Tepco failed to take necessary precautions. Clearly the handling of the nuclear crisis cannot be left to Tepco alone.

Tepco is circulating about 370 tons of water every day to cool the damaged reactors, but about 400 tons of groundwater are flowing into the basements of the reactor buildings every day and mixing with the cooling water.

This means that the amount of highly radioactive water that must be stored is increasing by 400 tons a day. Because the underground pools can no longer be used, this water must now be stored in aboveground tanks.

Tepco has stated that even in a worst possible leakage scenario, aboveground tanks would have a capacity of 5,000 tons of water, equivalent to 12 or 13 days’ worth of contaminated water. But space for building new tanks in the compound is decreasing and will eventually run out. The government, Tepco and outside experts must closely cooperate to come up with a feasible solution.

Leaks of radioactive water into the environment must be prevented at any cost.