The Nuclear Regulatory Commission has begun a Special Inspection at the Millstone Unit 3 nuclear power plant to further review repetitive problems involving a pump that is part of a reactor safety system.

The inspection will get under way today (Feb. 3) at the plant, which is located in Waterford, Conn., and operated by Dominion Nuclear Connecticut Inc.

The inspection, to be conducted by a four-member team, will focus on a turbine-driven auxiliary feedwater pump for the plant. The auxiliary, or back-up, feedwater system is one of several that can be used to help cool down the reactor following a shutdown by pumping water into the secondary side of the plant’s steam generators. The steam generators are essentially large heat exchangers that convert heat produced by the reactor into steam, which in turn is used to spin the plant’s turbine and generate electricity.

Among the areas to be reviewed during the Special Inspection are Dominion’s responses to the issues, including the adequacy and completeness of testing on the pump and root-cause evaluations of the problems. It will expand on earlier assessments performed by the NRC Resident Inspectors assigned to Millstone on a full-time basis and by NRC specialist inspectors.

"We have witnessed problems involving this safety-related component stretching back to last May," NRC Region I 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."

On May 15, 2013, at the end of a refueling and maintenance outage, plant personnel observed that the turbine-driven auxiliary feedwater pump was experiencing speed oscillations, or unexpected fluctuations, during testing. There were also problems involving the pump on several other dates, most recently on Jan. 23, 2014. The issues included oscillations and overspeeding.

NRC Resident Inspectors at Millstone have been closely following up on these issues with support from Region I specialist inspectors and other technical experts. For example, the third-quarter integrated inspection report for the plant includes a finding for an inadequate operability determination by the company related to the performance of the speedcontroller for the pump.

The inspection team will document its findings and conclusions in a report to be issued within 45 days of the end of the review.