The operator of the Fukushima Daiichi nuclear plant in Japan says about 300 tonnes of radioactive water has seeped from a storage tank, the worst leak in almost two and a half years of efforts to contain the effects of the 2011 earthquake and tsunami.
Tokyo Electric Power said yesterday it had detected a leak in one of the tanks that store water used to cool melted uranium fuel rods. A puddle that formed near the tank was emitting a radiation dose of 100 millisieverts an hour when measured a short distance above the surface, Tepco said – about 350,000 times higher than natural background levels.
Japan’s Nuclear Regulation Authority classified the leak as a “level one” incident, the lowest on an eight-point international scale. A spokesman confirmed it is the first time the NRA has attached a so-called INES rating to an incident at Fukushima since the government-linked watchdog was established last September.