Hundreds of tonnes of radioactive water leak from Fukushima

The operator of Japan’s tsunami-crippled nuclear power plant said on Tuesday that about 300 tonnes of highly radioactive water have leaked from one of the hundreds of storage tanks there – its worst leak yet from such a vessel.

Tokyo Electric Power Company (Tepco) said the contaminated water leaked from a steel storage tank at the wrecked Fukushima Dai-ichi plant. Tepco hasn’t figured out how or where the water leaked, but suspects it did so through a seam on the tank or a valve connected to a gutter around the tank.

Tepco said that because the tank is about 100 metres from the coastline, the leak does not pose an immediate threat to the sea. But Hideka Morimoto, a spokesman for Japan’s nuclear watchdog, the Nuclear Regulation Authority, said water could reach the sea via a drain gutter.

Four other tanks of the same design have had similar leaks since last year. The incidents have shaken confidence in the reliability of hundreds of tanks that are crucial for storing what has been a never-ending flow of contaminated water.

“We are extremely concerned,” Morimoto told reporters. He urged Tepco to quickly determine the cause of the leak and its possible effect on water management plans.