Operators of the San Onofre Nuclear Generating Station want to restart one of the reactors.
In a plan submitted Thursday to the Nuclear Regulatory Commission, Southern California Edison said Unit 2's components weren't as damaged as the ones in Unit 3, which is riddled with bum components.
Edison plans to operate the unit at 70 percent power, then shut it down for inspection after five months.
The plan said the utility has found and isolated the cause of the wear that closed the plant in January after a leak of radioactive steam. Technicians have isolated six tubes in Unit 2 that could be subject to the kind of vibration that causes them to burst.
They plugged those and 500 others among the thousands of heat-exchange tubes that allow the plant to function by boiling water to make steam that turns turbines.
Because of these precautions, Southern California Edison said it's now safe to operate Unit 2.
The plan cites no specific restart date. The NRC, which must sign off on the plan, is expected to spend months reviewing it.
Critics that are likely to lobby against the plan's approval include Friends of the Earth. The national environmental group released a statement Thursday morning calling Edison's proposal "a reckless gamble that flies in the face of the utility's claim that it puts safety ahead of profits."
Edison President Ron Litzinger issued a statement saying: "Safety is our top priority, and after conducting more than 170,000 inspections to understand and prevent the problem, and confirming the corrective actions we have taken to solve the problem with the top experts from around the world, we have concluded that Unit 2 at San Onofre can be operated safety and within industry norms. When implemented, this plan will get San Onofre Unit 2 back to providing reliable and clean energy to Southern Californians."
The leak in Unit 3 was caused by the steam tubes rubbing against one another, which caused their metal walls to wear thin, a phenomenon called fluid elastic instability.
Unit 2 was susceptible to the same phenomenon, but to a lesser degree than Unit 3, officials said. They said Unit 2 can be safely restarted at 70 percent power without triggering fluid elastic instability.
The restart plan envisions Edison installing early warning monitors that can detect extremely small leaks faster, and plant employees receiving additional training on how to respond to a leak.
—City News Service contributed to this report.