A mistake at a pump switch likely caused highly radioactive water to transfer to an emergency storage site for nearly a month at the Fukushima No. 1 nuclear plant, the plant’s operator said May 2.
A mistake at a pump switch likely caused highly radioactive water to transfer to an emergency storage site for nearly a month at the Fukushima No. 1 nuclear plant, the plant’s operator said May 2.
Tokyo Electric Power Co. officials estimate the pump was accidentally switched on sometime on March 20, based on changes in water levels in the basement of a building for waste processing.
Employees were operating a distribution switchboard that controls air-conditioning and other equipment on that day. The switchboard also included an unlabeled pump switch for water transfer, the officials said.
In mid-April, TEPCO employees discovered that an estimated 200 tons of radioactive water used to cool reactors had incorrectly been pumped to the basement of the building.
The plant operator said the error went undetected for such a long period of time because the area was a backup system.
“Because the basement of the building is an emergency transfer destination, we did not measure water levels there,” a TEPCO official said May 2.
TEPCO said it plans to reorganize the switchboard operations to prevent similar mishaps by separating frequently used functions from those rarely used, such as the pump switch.
It also said it will lock the switchboard when it is not in use.