The U.S. Nuclear Regulatory Commission (NRC) increased its level of oversight at the Millstone Unit 3 nuclear plant in Connecticut after the commission finalized a “white,” or low to moderate safety significance, inspection at the plant.
NRC inspectors determined that from May 2013 through February 2014, the unit’s turbine-driven auxiliary feedwater pump was operated improperly due to installation of an incorrect bearing. The problem displayed itself as two cases of unexpected fluctuations in reactor coolant flow from the pump and three trips of the pump due to overspeeding. The NRC conducted a special inspection at Millstone 3 in February and May in response to the problems with the auxiliary feedwater pump. In September, NRC began another special inspection in response to further unrelated problems with the pump after the pump failed quarterly surveillance tests in July and September.
Plant owner and operator Dominion Nuclear Connecticut (NYSE: D) has taken action to repair the pump and completed a root-cause evaluation, but the NRC is taking action due to the length of time it took for the issue to be addressed.
The backup 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.
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