A nuclear power plant in the village of Tokai, Ibaraki Prefecture, shut down a reactor Wednesday for the second time this week after a valve in one of its pumps malfunctioned, the operator said.
The mechanical trouble posed no danger of a radiation leak, Japan Atomic Power Company spokesman Masayuki Taguchi claimed.
The reactor at the Tokai No. 2 Power Station had just been restarted after a shutdown Sunday due to radioactive water leaks caused by problems with another set of valves. The reactor had resumed a test run last week after more than three months of inspections that began in April.
Wednesday's mishap involved a valve in the feed-water pump failing to send enough water from the condenser back into the reactor.
In the earlier problem, workers found two radioactive water leaks -- one at the entrance to a chamber linking the reactor to a turbine, and the other in a steam pipe in the chamber.