Tokyo Electric Power Co. said Tuesday it has failed to disclose leaks into the sea of rainwater containing radioactive substances from a drainage ditch linked to a building at its stricken Fukushima No. 1 nuclear power plant although it became aware of the leaks in April last year.
The building is highly contaminated with radioactive substances such as cesium that have been released from the plant since it was damaged in the March 2011 earthquake and tsunami.
As the drainage ditch in question is connected to the roof of the reactor 2 building, 29,400 becquerels of radioactive cesium per liter were detected from water accumulated on the rooftop, Tepco said.
The water also contained 52,000 becquerels of beta ray-emitting radioactive substances such as strontium-90.
The drainage ditch is linked to the Pacific Ocean. Some 1,050 becquerels of radioactive cesium and 1,500 becquerels of beta ray-emitting radioactive materials per liter were detected near an outlet leading to the sea.
Tepco said that there have been no major changes in the amount of radioactive substances detected in seawater collected from an area about 1 km from the drainage outlet.
The company saw water contaminated with high levels of radiation flowing to the plant’s port through another drainage ditch Sunday.
