Tokyo Electric Power Co. said Thursday about 100 tons of highly radioactive water overflowed and spilled from a tank at the Fukushima No. 1 plant.
The utility said it believes that the escaped water did not reach the ocean, as there was no drainage ditch that connects to the sea near the leaked area around the tank, which is in an area called H6.
At the crippled Fukushima No. 1 site, Tepco removes cesium from tainted water that flows into the basements of the crippled reactor turbine buildings daily. The water is put into storage tanks.
Tepco said the water was supposed to go to tanks placed at the E area, which is west of H6, but it went to the tank that was already storing water at H6 and overflowed.
According to the utility, two of the three valves of the pipe that control the water flow to the H6 area were open. Yet even if only the third valve was closed, the water should not have flowed, Tepco said, adding that the valve may be broken. But Tepco also admitted the three valves should have all been closed and is still not sure why two were left open.
While cesium was removed from the leaked water, it contains other radioactive materials, like strontium. Tepco said the level of those that emit beta rays was 230 million becquerels per liter.