ID :
318331
Thu, 02/20/2014 - 16:08
Auther :

100 Tons of Tainted Water Leak from Tank Area at Fukushima

Tokyo, Feb. 20 (Jiji Press)--Some 100 tons of highly radioactive water has escaped from one of storage tank areas at the Fukushima No. 1 nuclear power plant, its operator said Thursday. The water contained 230 million becquerels per liter of beta ray-emitting radioactive substances such as strontium-90, Tokyo Electric Power Co. <9501> said. The water leaked from one storage tank. A barrier at the H6 tank area failed to prevent the water from leaving the area, the company said. The plant was badly damaged in the March 2011 disaster. This is the worst leak of highly radioactive water at the plant since some 300 tons leaked in August last year. Last year's accident was rated Level 3, the fifth highest level, on the International Nuclear and Radiological Event Scale of zero to seven. The latest leak was detected around 11:25 p.m. Wednesday (2:25 p.m. GMT), when water was found to be dripping from a tank located some 700 meters west of the seawall, according to TEPCO. The water had escaped the area through a gutter. The level of beta-ray radiation on the surface of the water was 50 millisieverts per hour. Although an alarm signaling that the tank was almost full went off shortly after 2 p.m. Wednesday, TEPCO was unable to detect any irregularities at the time and concluded that the alarm was caused by equipment failure. The tank has three valves through which it receives tainted water. The valves should be closed, but two of them were open. Even the closed valve was not able to stop water entering. As a result, tainted water entered the tank, causing the leak. The leak slowed after the two valves were closed, according to TEPCO. The company said that 13,100 becquerels of radioactive cesium were detected in a water sample collected from the gutter. However, because there is no drainage, TEPCO said it does not believe the water made it into the ocean. Following the incident, the Nuclear Regulation Authority told TEPCO to prevent further leaks. The leak was brought under control around 5:40 a.m. Thursday. Fukushima Governor Yuhei Sato said at a meeting of prefectural officials in charge of nuclear affairs that the incident is regrettable as it undermines public trust. The leak stemmed from human error, he said, adding that TEPCO needs to take thorough measures to prevent similar incidents. END

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