A malfunctioning backup feedwater pump at the Millstone nuclear plant in Connecticut caught regulators’ eyes and they are sending inspectors to investigate.
This pump was also at the center of another special inspection earlier this year, said officials at the Nuclear Regulatory Commission (NRC).
On Monday the NRC sent three inspectors to unit 3 after the turbine-driven auxiliary pump unexpectedly stopped, then restarted without intervention during quarterly tests July 15 and Sept. 10.
Millstone workers fixed the pump, but in a release, an NRC official said the repetitive problems affecting it “continue to give the NRC concern.” The special inspection will study the cause of the problems and the adequacy of related testing.
In August, the agency issued a preliminary white finding after a special investigation into three over-speed trips of the same pump late last year and in January. According to the inspection report, that problem traced to the installation of an incorrect cam follower bearing.
Millstone 3 is a Westinghouse four-loop pressurized water reactor first licensed in 1986.