Updated

One of the melted reactors at tsunami-hit Fukushima nuclear power plant had a temporary loose of cooling when a worker accidentally bumped a switch while passing through a narrow isle of switch panels during an inspection and turned off the pumping system.

The plant operator, Tokyo Electric Power Co., said cooling for the No. 3 reactor, one of the three reactors that melted following the 2011 earthquake and tsunami, was out for nearly one hour Monday until a backup pump kicked in.

TEPCO said the reactor had enough water left inside and there was no temperature increase or radiation leak from the incident.

TEPCO acknowledged some other key switches are in similarly tight locations.