YAKIMA – Washington state’s only commercial nuclear reactor went back into service at 100 percent power Tuesday, several weeks after it had to be shut down when an electronic device failed.
The Columbia Generating Station was shut down July 30 after a faulty electronic device caused a steam valve to close, which led to a pressure increase in the reactor. Since then, crews have repaired the device and performed maintenance on steam valves and other systems.
The plant was reconnected to the northwest power grid at about 8:15 p.m. Sunday and began a gradual ascent to full power. The plant was at 100 percent power at 7:30 a.m. Tuesday, Energy Northwest, the company that operates the plant, said in a news release.
Columbia Generating Station is a boiling water reactor that produces 1,150 megawatts of electricity, which is sold to the Bonneville Power Administration for the Northwest electricity grid.
BPA officials had calculated that the shutdown was costing roughly $1 million each day.
The shutdown at Columbia Generating Station occurred after an electronic device failed and closed one of the reactor’s four steamflow valves. The valves channel nuclear-heated steam to the turbines driving the generator.
The closed valve caused an increase in pressure inside the reactor, and when the reactor attempted to automatically shut down, a panel indicated that not all of the 185 control rods had been fully inserted. The control rods are inserted into the reactor during a shutdown.
The control-room crew then executed a manual shutdown as a precaution. A review later showed the automatic shutdown was successful.
The problems triggered an alert in which state agencies prepared to respond if needed to help Benton and Franklin counties.
State emergency officials said there was no release of radiation and no danger to the public.
Formerly known as the Washington Public Power Supply System No. 2 reactor, Columbia Generating Station is the only one of five reactors started in the late 1970s to be completed before construction was halted in 1982-83.
The reactor is located on land leased from the U.S. Department of Energy within the boundaries of the Hanford nuclear reservation in south-central Washington state, but is a separate entity.
The reactor’s next scheduled shutdown is May 2005 for a refueling outage. The plant is shut down every two years to replace fuel inside the reactor.
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