While announcing that staff would meet with Southern California Edison (SCE) representatives on Dec. 18 to discuss the utility’s proposal to restart the San Onofre Nuclear Generating Station’s (SONGS’) Unit 2, the Nuclear Regulatory Commission (NRC) warned that the meeting was "only one step in a long process," and that "a final decision on whether San Onofre can restart is months away."
The discussion in Rockville, Md., will include the agency’s requests for more information on SCE’s October-submitted restart plan for the 2,150-MW plant’s Unit 2. The unit has been shut down since Jan. 9 after issues were identified in its steam generator tubes during a planned refueling and maintenance outage. The plant’s Unit 3 was later shut down on Jan. 31 after leaks were also detected in the steam generator tubes of that unit.
A prior determination found that the tube-to-tube wear in both units’ steam generators was likely caused by a "fluid elastic instability," a combination of high–steam velocity and low-moisture conditions in specific locations of the tube bundles and ineffective tube supports in the same locations. If it obtained the NRC’s approval to restart, SCE proposed to run Unit 2 at 70% power for five months to prevent the vibration-causing environment by decreasing steam velocity and increasing moisture content. It would then shut down the unit for inspection.
NRC spokesperson Scott Burnell said on Tuesday that staff, "as part of their usual process, isn’t accepting SCE’s plan at face value." It had provided more technical questions for the utility to answer during the public meeting. "While SCE might need to discuss some information in a non-public part of the meeting, all the staff’s questions will be part of the public session," he said.
Sources: POWERnews, SCE, NRC
—Sonal Patel, Senior Writer (@POWERmagazine)