The damaged plant is likely to remain sidelined until at least the end of August while investigators probe excessive wear in tubing that carries radioactive water, the plant’s operator said Thursday.
The officials say that if a heat wave hits while the twin-reactor plant is offline, rotating blackouts are a possibility. Utilities have been scrambling to find replacement power as a precaution, including restarting two retired natural gas-fired plants in Orange County.
Southern California Edison said in a statement that the company plans by the end of July to submit a plan to federal regulators to restart the Unit 2 reactor, where damage to tubes in its steam generators has been less severe than in its twin, Unit 3.
A proposal to restart either reactor must be approved by the Nuclear Regulatory Commission, and that review could take weeks or longer.
Edison spokeswoman Jennifer Manfre said it’s likely the plant between San Diego and Los Angeles will remain shuttered at least through August.
The trouble began to unfold in January, when the Unit 3 reactor was shut down as a precaution after a tube break. Traces of radiation escaped at the time, but officials said there was no danger to workers or neighbors. Unit 2 had been taken offline earlier that month for maintenance, but investigators later found unexpected wear on hundreds of tubes in both units.
Gradual wear is common in such tubing, but the rate of erosion in some tubes at San Onofre alarmed officials since the generators are relatively new. The company has said 1,300 tubes will be taken out of service, although the number is well within the margin to allow the generators to keep operating.
The company has found that the tube wear is being caused by vibration and friction with adjacent tubes and bracing, but investigators have yet to say why that’s happening or how they will fix it.
Edison initially targeted a June restart for at least one of the twin reactors. A tentative plan called for restarting and running the seaside reactors at lower power, at least for several months, because engineers believe that will ease vibration that could be eroding tubes.
The NRC has said there is no timetable to restart the reactors, which were replaced in 2009 and 2010 in a $670 million overhaul.
About 7.4 million Californians live within 50 miles of San Onofre, which can power 1.4 million homes.
Safety issues at the plant have attracted congressional scrutiny, and some officials in nearby communities have been calling for San Onofre to shut down permanently. The Irvine City Council urged the NRC to thoroughly review safety conditions at the plant before it is considered for relicensing in 2022.
Edison has said safety for the public and its employees is the company’s top concern.
The plant is owned by SCE, San Diego Gas & Electric and the city of Riverside. The Unit 1 reactor operated from 1968 to 1992, when it was shut down and dismantled.
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