WATERFORD, Conn. (AP) -- Federal regulators on Monday began an inspection at Connecticut's nuclear power plant to find out what's behind troubles with a pump in the safety system.
The Nuclear Regulatory Commission's inspection at the Millstone Unit 3 is focusing on a turbine-driven auxiliary pump used to help cool down the reactor after a shutdown by pumping water into steam generators.
"We have witnessed problems involving this safety-related component stretching back to last May," regional NRC administrator Bill Dean said. "The fact that these issues occurred on multiple occasions despite repeated efforts to repair this component has prompted us to take a closer look at the situation."
At the end of a refueling and maintenance outage on May 15, plant workers observed that a turbine-driven pump was experiencing unexpected fluctuations during testing, federal regulators said. Other problems related to unexpected fluctuations and overspeeding were reported on other dates, most recently on Jan. 23.
NRC spokesman Neil Sheehan said the persistent problems "warrant a higher profile."
Millstone spokesman Ken Holt said the plant, which is owned by Dominion Resources Inc., has been working on the problem and has brought in outside experts to help. Repairs have made the pump operable, he said.
The auxiliary, or back-up, feedwater system is one of several used to help cool down the reactor after a shutdown. It pumps water into the steam generators that are heat exchangers converting heat produced by the reactor into steam used to spin the plant's turbine and generate electricity.