The U.S. Nuclear Regulatory Commission (NRC) said April 4 that Chairman Gregory Jaczko will visit the 2,200 MW San Onofre nuclear power plant in California. Both of the plant’s reactors have been shut down because of excessive wear in tubing, according to The Associated Press.
Instruments detected a leak in the steam generator tube in Unit 3 on Jan. 31 and workers safely shut it down. Unit 2 had been offline for a scheduled refueling outage since Jan. 9, but subsequent inspections of both units have identified unusual wear in many tubes of the steam generators. The Mitsubishi Heavy Industries generators were replaced in January 2010 at Unit 2 and January 2011 in Unit 3.
The tube wear is reportedly caused by friction and vibration with adjacent tubes and bracing, but investigators are not sure why that is happening, the article said.
On March 28, the NRC issued a Confirmatory Action Letter documenting actions that plant owner Southern California Edison (SCE) must take before restarting both units. SCE has reportedly said that 321 tubes with excessive wear will be plugged and taken out of service. San Diego Gas & Electric and the city of Riverside also own the plant.
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