San Onofre has been shut down since Jan. 31, when a tube that carries hot, radioactive water in one of the plant's newly installed steam generators in the Unit 3 reactor sprang a leak. The mishap released a small amount of radioactive steam.
The reactor was taken offline and Southern California Edison, the plant's operator, began pressure-testing 129 tubes that showed excessive wear, while the U.S. Nuclear Regulatory Commission dispatched a team to investigate the issue. Since then, eight tubes have failed pressure stress tests. Meanwhile, in Unit 2, the plant's other working reactor, which had been shut down for routine maintenance since early January, they found excessive wear and tear on 192 more tubes.
Jennifer Manfre, a spokeswoman with Edison, said the company is planning for the possibility that the plant could be offline through the summer.
If that happens, it will be the first time that one of California's two nuclear plants has been shut down for an extended period during the summer months when demand peaks, said Stephanie McCorkle, a spokeswoman with California Independent System Operator, which operates the state's wholesale power grid.
So far, with energy demand low due to mild weather, the plant's shutdown has had no impact on service.
In a report presented to the Independent System Operator board Thursday, staffers said that in a major heat wave or transmission line outage during the peak season, South Orange County and the San Diego and Los Angeles areas could face energy shortages without the 2,200 megawatts of power generated by San Onofre.
To prevent that, officials plan to produce more energy from other sources and convince customers to scale back on demand.
"If, in fact, we do nothing, there could be some potential issues down there," said ISO Chief Executive Stephen Berberich. "We don't intend to do nothing."
Independent System Operator staffers said that the danger of outages could be mitigated by bringing back two retired generating units at a natural gas power plant in Huntington Beach, as well as stepping up transmission upgrades and calling for voluntary conservation through "flex alerts" and other measures.
Manfre said Edison is working with the Independent System Operator and San Diego Gas & Electric, which owns a 20% share in the plant, to plan for the summer. Among other measures, she said the company is accelerating a transmission project that will serve parts of South Orange County, and is in discussions with the California Public Utilities Commission to implement a rate savings incentive program for customers who reduce their usage.
Some observers voiced concerns that officials will use consumers' fear of rolling blackouts to push the plant back into service before the issues are fixed. S. David Freeman, former head of the Los Angeles Department of Water & Power, wrote a letter to the Independent System Operator chastising officials there for raising the specter of rolling blackouts in previous public statements.
"The problems at San Onofre are serious enough to require the NRC to dispatch a team to the plant site to discover the cause of the problems," he wrote. "They don't need the pressure caused by the fear of rolling blackouts fanned by the spokesman for the ISO."
McCorkle said the power grid operator is most concerned about safety and is not pushing for a quick return to service for San Onofre.