Tokyo Electric Power Co. said Thursday that radiation rose to a new record in water collected from a drainage ditch at its stricken Fukushima No. 1 nuclear plant.
Tepco said it detected a maximum of 140,000 becquerels per liter of beta ray-emitting substances, including strontium, from a water sample collected Wednesday from the ditch, which extends to the sea beyond the plant’s port.
The figure is 2.3 times higher than the previous record of 59,000 becquerels detected in water sampled at the same location Tuesday, and was more than 11 times the previous day’s reading.
The measurement location is about 600 meters from the open ocean and close to the storage tank that leaked some 300 tons of radioactive water in August.
Tepco said rainwater may have carried radioactive materials in surrounding areas into the drainage ditch.
Sandbags were placed downstream, but heavy rain may have caused the water in the ditch to overflow them and enter the ocean.
Also on Thursday, Tepco started transferring radioactive water that has built up inside the tanks’ flood enclosures to a covered reservoir ahead of heavy rain expected from fresh typhoons approaching Japan.