The operator of the crisis-ridden Fukushima nuclear power plant said it found a new leak near the tanks holding contaminated water at the disaster site.
Beta radiation readings of 230 million becquerels per liter were taken in a water sample collected from a gutter on top of the leaked tank at the plant – 2.3million times the safe limit set by the Japanese government.
The radioactive water overflowed from the 10-meter long tank after two valves – which were supposed to be closed – had been opened, operator Tepco admitted.
The leak was found 700meters from the ocean in an area isolated from any drainage ditch. About 26,400 gallons of water may have escaped a concrete barrier.
“Such a water leak was found despite a variety of measures taken by the company,” said Tepco spokesman Masayuki Ono.
“We are sorry to have caused concern,” he said.
Japan’s nuclear regulator, which is planning to check the utility’s probe of the leak and planned preventative measures, said today that it has asked Tepco to ensure no more leaks from the same type of water storage tanks occur.
The leak highlights difficulties for the regulator as it seeks to force Tepco to limit radiation at the site without slowing down its decommissioning.
“We need a balance of the best regulation and also the quickest decommissioning at Fukushima Dai-Ichi because we really want to have the reduction of the risk at the site,” Nuclear Regulation Authority commissioner Toyoshi Fuketa said.
Tepco has installed about a thousand tanks at Fukushima to store hundreds of thousands of tons of water used to cool fuel after the nuclear accident in March 2011.
Some 300tons of contaminated groundwater seep into the ocean each day at the Dai-Ichi station 150 miles north of Tokyo.