Nuclear Shutdown Linked to Crash : Power Flaw After Plane Accident Affects Diablo Canyon

The private plane that crashed into power lines Sunday near Coalinga, killing both persons on board and closing Interstate 5 for more than 15 hours, also forced a partial shutdown of the Diablo Canyon nuclear power plant, authorities said Monday.

Both nuclear reactors at the Pacific Gas & Electric Co. plant, about 40 miles southwest of the crash site, were operating at full power when sensors detected a fluctuation in voltage caused by the plane’s collision with the power lines.

No equipment at the plant was damaged and there was no threat of a nuclear safety problem, the company and a spokesman for the U.S. Nuclear Regulatory Commission said.

Freeway Reopened

Interstate 5 was reopened at 11 a.m. Monday, 15 1/2 hours after the 7:30 p.m. crash Sunday. Traffic on the state’s principal north-south freeway had been rerouted through a 10-mile detour.

One of the Diablo reactors, Unit 1, shut down instantly because its non-nuclear electrical systems were being operated manually at the time of the crash and could not react fast enough to make adjustments for the voltage fluctuation.

The Unit 2 reactor’s non-nuclear electrical systems were on automatic and were able to quickly make necessary adjustments that allowed the reactor to continue to operate normally, PG&E; said.

The plane, a Cessna 182, exploded on impact, sending one 500,000-volt and two 230,000-volt power lines crashing down across Interstate 5 and damaging seven transmission line towers.

The downed power lines also entangled a northbound sports car, throwing it into a 180-degree spin. The driver was not hurt, the California Highway Patrol said.

Repairs to Lines

PG&E; said Monday that it would take several more days to repair the lines but that power had been re-routed on two other lines from Diablo Canyon.

Meanwhile, the Fresno County coroner’s office on Monday identified the two men killed in the plane crash as Ronald Roy McLain, 37, the pilot, and his passenger, John Lawrence Bianco Jr., 44, both of Visalia.

Coincidentally, PG&E; had been working to correct a problem with its voltage regulators at its $5.8-billion plant. The company said it had planned to make the changes Monday.

Had the changes been completed before the plane crash, Unit 1 would have been back on automatic operation and probably would not have shut down, PG&E; said.

The problems with the voltage regulators were first noticed 1 1/2 weeks ago when there was an unexplained “upset” in electrical power originating in Utah, said Warren Raymond, assistant to James D. Shiffer, PG&E; vice president for nuclear power generation.

He said an upset could be caused by any number of things, including a sudden increase in voltage or the loss of a power line.