Electrical Blaze at San Onofre Nuclear Plant Shuts Down 1 Reactor Unit

An electrical fire at the San Onofre nuclear power plant shut down Unit 2 of the reactor Thursday, but no one was injured and no radiation was released, Southern California Edison Co. officials said.

Under Nuclear Regulatory Commission regulations, the incident is being termed “an unusual event.” But “there was no release or potential release of radiation,” Edison communications representative David Barron said.

Unit 2 of the reactor probably will remain out of operation for the next week until the fire area can be cleaned and the precise cause of the blaze nailed down, Barron added.

The unit had been operating under full power when the fire broke out. It produces 1,100 megawatts of electricity, serving about 750,000 homes in Southern California. Other Southern California Edison Co. plants will generate additional energy to make up for the loss of power from Unit 2, Barron said.

In Non-Nuclear Area

The fire began at 10:14 a.m. Thursday in the rear of a turbine generator that measures about 10 by 20 feet and is on “the non-nuclear side of the plant,” Barron said. Several hundred workers were in the plant at the time.

Black smoke from the blaze could be seen by drivers on Interstate 5, said Dave Kusumoto, a spokesman for San Diego Gas & Electric Co., which owns 20% of the nuclear plant.

When the fire started, however, the turbine automatically shut down and the reactor then shut off, too, Barron said.

Within five minutes, automatic fire extinguishers put out the blaze, he said. An Edison fire crew stationed at the power plant was then able to go into the rear of the generator and start cleaning up. An engine company from Camp Pendleton was on standby but did not go to the scene.

Sparking in Brushes

By late Thursday, Edison officials had targeted a likely cause for the fire. “It appears we had failures in what are called the brushes,” said plant site manager Harold Ray, an Edison vice president. Some workers noticed “a sparking” in the brushes that are used to transfer electricity from the rotating part of the electrical system to the stationary part of the system, he explained.

“They (workers) saw the sparking. They went out and closed the door on the cabinet and went out to get assistance. And before they could take action, the fire got started,” Ray said.

Edison officials said they could not put a dollar value on the damage, but Ray said there was little evidence of the fire in the turbine generator itself.

“It’s not scorched or singed. There’s no evidence of fire other than right at the location of these brushes. It is just a lot of soot,” he said.

The fire in Unit 2 was the second at the power plant this year. In April, a minor oil fire forced the shutdown of Unit 3 for several days, Barron said.

The power plant’s other units, 1 and 3, are providing 456 megawatts and 1,100 megawatts respectively.