Beltway: San Onofre in Unchartered Territory

By Published On: June 1, 2012

The 2,200 MW San Onofre nuclear power plant is to remain off line for months. The nuclear facility operated by Southern California Edison “will remain out of service throughout the summer due to premature wear in the steam units of these units,” states the North American Electric Reliability Corp.’s 2012 Summer Reliability Report released May 30. It also dismissed reports of a September 1 startup date after federal regulators made it clear that a firm date is not in the cards. “There is no timeframe” for inspecting or approving the operator’s request to restart the facility, said Victor Dricks, Nuclear Regulatory Commission spokesperson. There are no comparable restarts at other nuclear facilities that have been closed because the plants and circumstances “are unique.” Dricks added, “There is no expedited process” for the commission to handle a request from Edison once filed with federal regulators. A possible start-up may be further delayed after Edison revealed that there was an earlier problem at the plant. Edison announced May 29 it reported to the NRC on May 14 that the utility discovered a malfunctioning vibration sensor “that might incorrectly initiate a shutdown of the emergency diesel generators when a loss of off-site power happens at the same time as an earthquake.” The sensor is supposed to shut the diesel generators down during excessive vibration. “The sensors have been disabled until they are fully analyzed,” Jennifer Manfre, Edison spokesperson, stated May 31. Edison is obligated to get the commission’s permission before restarting the nuclear facility--either partially or fully. It must comply with the specifics detailed in federal regulator’s March 27 action letter, according to Dricks. “This Confirmatory Action Letter formalizes commitments that Southern California Edison has made to ensure that the cause of the tube wear in both steam generators is understood and appropriately addressed in order to ensure safe operation,” wrote NRC Region IV administrator Elmo Collins at that time. The conditions include requiring Edison to plug all tubes in the two units that have “wear in excess of industry guidelines, as well as all tubes susceptible to this wear because of their location.” The utility also was directed to find the causes of the tube degradation and establish a protocol of inspections. Edison’s “number one priority is, and has been, the health and safety of the public and its employees,” the utility restated this week. Blackouts in the San Diego and Los Angeles areas are likely if temperatures are high or there are unexpected generation or transmission outages, according to the quasi-governmental NERC. In addition, with an expected 14,000 MW of imports into the entire state “increased reliance on transmission ties to import the required power could further stress the system.” San Onofre’s Unit 2 was shut down Jan. 9 for a planned outage and refueling. Unit 3 was taken out of service Jan. 31 when a radioactive leak in a steam generator tube was discovered. Subsequently, inspections revealed unprecedented levels of tube wall thinning and wear in the fairly new steam units, which were manufactured by Mitsubishi. The combination of re-firing two old units at Huntington Beach, along with increased demand-response dispatching and interruptible load programs with public agencies and the military, are expected to supply 2,750 MW to help counter San Onofre’s outage.

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