A plan to restart the off-line San Onofre Nuclear Generating Station has been submitted to the Nuclear Regulatory Commission for approval, the plant's operator announced Thursday.
The plan, which cites no specific restart date, calls for one of two units at the northern San Diego County facility to be powered up at 70 percent power for a five-month trial period, according to Southern California Edison, which runs the plant and co-owns it with San Diego Gas & Electric and the city of Riverside.
The commission, which must sign off on the restart plan, is expected to spend months reviewing it.
Critics expected to lobby against the proposal include Friends of the Earth. The environmental group released a statement this morning, calling the restart plan "a reckless gamble that flies in the face of (SCE's) claim that it puts safety ahead of profits."
The plant's power generators -- called Unit 2 and Unit 3 -- were deactivated in January. Unit 2 was taken off-line for planned maintenance, while Unit 3 was abruptly shut down after a leak was detected in one of its steam generator tubes.
Edison is proposing to restart Unit 2 while Unit 3 remains offline for further inspection, analysis and testing.
"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," SCE President Ron Litzinger said. "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 tube-to-tube wear due to a phenomenon called "fluid elastic instability," Edison reported. The utility said a combination of high-steam velocity and low-moisture conditions in specific locations of tube bundles and ineffective tube support systems in the same bundle locations causes the phenomenon and subsequent wear, leading to leaks.
Unit 2 was also susceptible to the same vibration-causing environment but to a lesser degree than Unit 3, SCE officials said, noting Unit 2 can be safely restarted at 70 percent power without triggering fluid elastic instability. Some critics argued against the assertion, saying the designs of the units are essentially the same.
Edison officials said if the restart plan is approved, they would operate Unit 2 for five months and then shut it down to inspect it for leaks.
The plan also envisions Edison installing early warning monitors on the unit that can detect extremely small leaks faster and plant employees receiving additional training on how to respond to a leak.
Sen. Barbara Boxer, D-Calif., who chairs the Senate's Environment and Public Works Committee, called on the nuclear commission Thursday to complete its investigation into safety concerns at the plant before considering the request to restart it.
In a letter to NRC head Allison Macfarlane, Boxer said the regulatory body's focus "must be on fulfilling its safety mission and providing the millions of people who live near San Onofre with the peace of mind that the reactors are safe."
"I want to make certain that the NRC fully understands the causes of the unusual tube deterioration, is confident that the plant can be safely restarted given the current condition of the tubes and has determined that the facility can be safely operated in the future," the senator wrote.
Boxer asked Macfarlane to provide those assurances by Oct. 12.