North Anna unit 2 shut down again Tuesday following its second attempt this month to restart following a refueling outage.Operators manually tripped the reactor from 98 percent power just after 3 p.m. when a feed water pump valve closed for unknown reasons and caused a main feed water system transient, according to a report filed with the Nuclear Regulatory Commission. Safety systems, including the reactor protection system and auxiliary feed water pumps, functioned as designed while the unit was safely shut down, according to the report.The Westinghouse reactor had entered a refueling outage April 7. That outage was scheduled to end on May 10, but the unit shut down manually from 60 percent power during the restart, when the NRC said workers reported increased vibration and arcing on a bearing of the main generator exciter.Unit 1 at the Virginia plant operated by Dominion was unaffected.
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