LOS ANGELES — The U.S. Navy is nearing a first-time agreement to curb electricity use at its sprawling San Diego-area bases if power runs short in Southern California this summer, a deal intended to diminish the threat of blackouts while the troubled San Onofre nuclear plant remains offline.
The Navy is San Diego Gas &Electric’s largest customer, and the utility has been working on an agreement under which the Navy would temporarily reduce its energy consumption if regional supplies get scarce. In exchange, the Navy would receive a break on electricity rates.
The company has similar agreements with large industrial customers, which can slash the demand for power at critical times and keep the lights burning.
State energy officials say Southern California could be hit by rotating blackouts this summer if a heat wave hits while San Onofre’s twin reactors remain dark, though some activists insist adequate reserves are on hand.
The plant, which can crank out enough electricity for 1.4 million homes, has been shut down for nearly three months while investigators try to determine the cause of excessive wear on hundreds of alloy tubes that carries radioactive water in its massive steam generators.
The loss of the nuclear plant also makes it harder to import power into the San Diego area, where reliable energy transmission has long been a thorny issue.
“If the (San Onofre) units remain down, you obviously have less power supply down there. If you have a transmission line go down, or another generator go down, you are in a very tight situation,” said Bruce Kaneshiro, a supervisor at the state Public Utilities Commission.
Capt. Dora Lockwood, a Navy spokeswoman, said the company is working on a target for power reductions, if needed, at the numerous Navy installations in San Diego County, which include Naval Base San Diego, the Naval Air Station North Island in Coronado and Miramar Marine Corps Air Station.
“We will do our best, while preserving our capability to carry out our mission responsibilities, to support their request,” Lockwood said.
SDG&E spokeswoman Jennifer Ramp said a deal could be finalized shortly.
“The military is aware of the challenges this summer,” Ramp said.
State energy planners have been working on a strategy to find replacement power in the region and reduce demand if hot weather hits while the nuclear plant is sidelined. Those plans include restarting two retired power plants in Huntington Beach, urging conservation, such as using air conditioners sparingly, and seeking temporary power cutbacks, if needed, from the military and public agencies.
On Friday, Southern California Edison, which operates San Onofre, asked state regulators to approve a plan to promote conservation among its commercial customers in Orange County — they can earn a 10 percent rebate by cutting consumption by 10 percent during the summer, when demand is high.
No date has been set to restart either reactor, which are located between San Diego and Los Angeles.
It takes power to move power, and the restart of the Huntington Beach plants will allow increased transmission into the region, said Stephanie McCorkle, a spokeswoman for the agency that operates the state’s wholesale power system, the California Independent System Operator.
The loss of the nuclear plant can restrict power imports into San Diego area by up to 30 percent. The San Diego utility hopes a new, $1.8 billion transmission line will be completed by summer, which would help fill any shortages.
The twin, natural gas-fired plants in Huntington Beach were retired earlier this year. The gas line feeding the plants was severed and 3-foot holes were cut in the boilers, a requirement after taking them out of service.
Eric Pendergraft, president of AES Southland, which operates the Huntington Beach plants, said Thursday that repairs to the boilers and other equipment would begin shortly. He predicted the plants would be ready to restart in mid-May.
The company has to strike agreements with the state wholesale power system before returning to service.
Some officials in nearby communities have been calling for San Onofre to shut down permanently, and last week the Irvine City Council urged the Nuclear Regulatory Commission to thoroughly review safety conditions at the plant before it is considered for relicensing in 2022. The city requested in a letter that the evacuation zone be expanded to 50 miles, from 10 miles.
The trouble at San Onofre began to unfold in late January, when the Unit 3 reactor was shut down as a precaution after a tube break. Traces of radiation escaped, but officials said there was no danger to workers or neighbors. Unit 2 had been taken offline earlier in January for routine maintenance and refueling, but investigators later found unusual wear on tubing in both units.
The excessive tube wear has raised questions about the integrity and safety of replacement generators the company installed in a multimillion-dollar makeover in 2009 and 2010.
The plant’s four steam generators each contain nearly 10,000 tubes that carry hot, pressurized water from the reactors. The tubes are a critical safety barrier — if one or more break, there is the potential that radioactivity could escape into the atmosphere. Also, serious leaks can drain cooling water from a reactor.
Test results show that two types of wear have occurred at both units — tubes are rubbing and vibrating against adjacent tubes, as well as against support structures inside the generators.
Federal and company investigators are trying to determine why that is happening.
An environmental group, Friends of the Earth, has claimed SCE misled the NRC about design changes that it said are the likely culprit in excessive tube wear and has urged more detailed study before the reactors are restarted.
S. David Freeman, an adviser to the group, said last month that warnings about blackouts are unnecessary, since power can be managed to avoid any customer outages, even without San Onofre.
“California is not and cannot be one power plant away from rolling blackouts,” Freeman, a former general manager at the Los Angeles Department of Water and Power, wrote to the Independent System Operator.
He said it was disturbing that state energy officials are “warning of a return of blackouts unless a very troubled nuclear plant is rushed back into operation.”
SCE has said safety remains its priority.
The plant is owned by Edison, SDG&E and the City of Riverside. The Unit 1 reactor operated from 1968 to 1992, when it was shut down and dismantled.