An investigation into the cause of last week’s power interruption at Fukushima nuclear plant confirmed a rat was responsible for the blackout that stopped the cooling systems at the plant last Monday.
Tokyo Electric Power Co. (TEPCO) reported two days ago, on March 25, that a rat found electrocuted beneath a temporary switchboard was the reason for the 29-hour-long blackout that extended at Fukushima nuclear plant on March 18.
The blackout, which affected critical cooling systems at the nuclear plant’s spent fuel storage pools last Monday, lasted for more than one day, according to the international press. Electricity was partially restored on Tuesday, March 19, but the supply was brought under control only after 29 hours since the original outage.
TEPCO investigators found a terminal with scorch marks inside the switchboard’s housing and a dead rat, clearly electrocuted, lying on the floor nearby. A short-circuit was caused by the nearly 25 centimetres long rat climbing across live terminals, investigators said. They believe the animal entered through an opening in the building.
No other problems were spotted in the other switchboards, TEPCO said.
In order to avoid for the same problem to happen again, workers have disconnected key devices from the temporary switchboard, which remains outdoors, and reconnected them to rat-proof, indoor switchboard.