As Edison waits for a decision on a restart, the plant faces a host of lingering issues. The future of the heavily damaged Unit 3 reactor is not known — its nuclear fuel has been removed. Environmental groups are challenging various aspects of Edison's plans.
And it's not known if the damaged generators can ever be repaired and operated at full power.
"I don't know where that's going," said NRC Deputy Regional Administrator Art Howell, who heads the agency team overseeing San Onofre.
Friends of the Earth, a group critical of the nuclear power industry, is among several environmental organizations pushing the NRC to require Edison to seek an amendment to its operating license to restart the plant, a process that would involve court-like hearings and could take up to two years.
The generators, which resemble massive steel fire hydrants, control heat in the reactors and operate something like a car radiator. At San Onofre, each one stands 65 feet high, weighs 1.3 million pounds and has 9,727 U-shaped tubes inside, each three-quarters of an inch in diameter.
Cracked and corroded generator tubing has vexed the nation's nuclear industry for years.
Decaying generator tubes helped push San Onofre's Unit 1 reactor into retirement in 1992, even though it was designed to run until 2004. The following year, the Trojan nuclear plant, near Portland, Ore., was shuttered because of microscopic cracks in steam generator tubes, cutting years off its expected lifespan.
San Onofre 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.