Diablo Canyon Reactor 1 Restarted

The Diablo Canyon nuclear power plant resumed testing at half of its capacity power after two automatic shutdowns due to malfunctions last week, a spokesman said Saturday.

The Unit 1 reactor was started up again late Friday after a feed-water pump shut down the reactor that afternoon, said Dick Davin, spokesman for the plant owner, Pacific Gas & Electric Co. The reactor ran through the night at low power before being brought up to 50% capacity Saturday in preparation for a second try at a “load rejection” test, which had triggered an automatic shutdown on Wednesday, Davin said.

Ron Weinberg, another plant spokesman, previously explained that Friday’s incident occurred when a main feed-water pump shut off while the plant’s turbine-generator was being prepared to feed power into the company’s electrical grid system.

The problem was reported routinely to the Nuclear Regulatory Commission, Weinberg said.

A shutdown on Wednesday occurred during a test of the plant’s ability to cut power suddenly. A fail-safe mechanism shut off the reactor as technicians tried to decrease the power output of the plant from 50% to 5%, Weinberg said, adding that the problem has since been corrected.

Operators had restarted the reactor Thursday night and were preparing to return it to 50% of its full-capacity power of 1.1 million kilowatts at the time of Friday’s shutdown, Weinberg said.

Fifty percent of capacity is the highest output that plant operators have attempted with the reactor.