San Onofre FAQ: All you need to know about the troubled nuclear plant

Evening sets on the San Onofre atomic power plant in northern San Diego County, south of San Clemente, California.
Evening sets on the San Onofre atomic power plant in northern San Diego County, south of San Clemente, California.
David McNew/Getty Images

Why should I care what happens to San Onofre?

If you’re one of the 7.4 million people who live within 50 miles of the plant, there’s the issue of living near a nuclear power plant that’s experienced unprecedented operating problems that are still not fully understood by the nuclear industry. If you’re among the 22 million or so people who live in Southern California, then chances are you’ve used the power generated by the San Onofre Nuclear Generating Station. Until Southern California Edison took it offline nine months ago, the plant was our area’s biggest source of power and one of the largest nuclear plants in the country.

Why did the plant shut down?

The Unit 3 reactor was shut down as a precaution after a steam generator tube leak at the end of January. Traces of radiation escaped at the time, but officials said there was no danger to workers or neighbors. Unit 2 had been taken offline a few weeks earlier for maintenance, but inspectors later found unexpected wear on hundreds of tubes inside steam generators in both units.

Those four steam generators were installed at San Onofre during a $670 million overhaul in 2009 and 2010. Tests found some tubes were so badly corroded that they could fail and possibly release radiation, a stunning finding inside the nearly new equipment.

RELATED: California plans for an energy future without San Onofre's nuclear power

What has Edison proposed?

Southern California Edison, which operates the plant, has asked the Nuclear Regulatory Commission (NRC) for permission to operate Unit 2 at 70 percent power for five months, then shut it down for inspections.

Edison hasn’t announced any plans for restarting Unit 3, and company executives have left open the possibility its generators could be scrapped.

What are the main objections to reopening the plant?

Even strong supporters of nuclear power point out that the problems at San Onofre have been without precedent in the nuclear industry.

“The situation that San Onofre faces remains in uncharted territory, given how unique the problems are that they face,” says Per Peterson, professor of nuclear engineering at UC Berkeley.

Those who live near the plant, like Gene Stone, say what Edison is doing amounts to a science experiment in their backyard.

“They’re asking to experiment with our lives, our safety, our children, our food, our homes and our economy,” said Stone.

Anti-nuclear groups also say San Onofre has a poor safety record and that the plant would be compromised in an earthquake.

If San Onofre is so crucial to Southern California’s power supply, why haven’t there been any blackouts the last few months?

Officials at California-ISO, which manages the state’s power grid, say that conservation measures, a tepid economy, and a mild summer helped them get through this summer without San Onofre.

A natural gas power plant in Huntington Beach was brought back into operation this summer, but it can’t continue operating because its carbon credits expire.

What happens next?

The NRC will review Edison’s proposal for restarting Unit 2. “This could take a number of months,” NRC Chairman Allison Macfarlane said in a statement. “Our inspections and review will be painstaking, thorough and will not be rushed.”

The agency says it will hold public meetings near the plant to discuss the proposal.

There’s also a public meeting on Oct 9th, but the NRC has said it hasn’t had enough time to review Edison’s restart proposal to discuss it at that meeting.

Where can I find out more?

Links from both sides are below.