The Nuclear Regulatory Commission has sent inspectors to Connecticut's Millstone nuclear plant to investigate a malfunctioning backup feedwater pump also at the center of another special inspection earlier this year.
On Monday the agency announced it had dispatched 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. The pump has since been fixed, 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 was traced to the installation of an incorrect cam follower bearing.
Millstone 3 is a Westinghouse four-loop pressurized water reactor first licensed in 1986. Both units at the Dominion plant are currently in the licensee response column of the NRC's action matrix.