The NW’s only nuclear power plant is back on the grid after a longer than expected outage

The Columbia Generating Station, the Northwest’s only nuclear power plant, reconnected to the electric grid early Monday morning, ending its refueling and maintenance outage.

The plant was off line for about 44 days, nine days longer than planned.

More equipment and resources than planned were needed for maintenance on a feedwater valve, said Energy Northwest spokesperson Kelly Rae.

In addition, workers had some equipment challenges as it wrapped up the outage work.

“We took the time to complete outage work with quality, and we’re bringing the station back with increased reliability,” said Grover Hettel, Energy Northwest chief nuclear officer.

The Energy Northwest nuclear power plant was back on the grid before summer’s higher demand for electricity. The plant produces about 10% of the electricity used in Washington state.

The Columbia Generating Station is shut down every other spring, when electricity demand is low and hydropower from spring snowmelt is plentiful for refueling.

“Outage work is a rigorous, complex sequence of 24/7 activity,” Hettel said. “It requires several years of planning and a highly skilled team to complete.”

The outage is used to add fresh fuel to the reactor core and to allow maintenance that is difficult while the plant is operating.

During the outage just completed, 248 of 764 nuclear fuel assemblies in the plant’s reactor core were replaced with fresh fuel.

The fuel that had been in the reactor core for six years was placed in the adjacent used fuel pool to remove residual heat for at least five years and then will be moved to Energy Northwest’s outdoor dry-cask storage.

Crews also used the outage to inspect a high-pressure turbine and moisture separator reheaters; refurbish a feedwater drive turbine; replace the roofing material on the turbine building and repair the reactor feedwater valve that took longer than expected, plus other work to inspect and diagnose possible issues with the plant’s components.

Before disconnecting from the grid May 5, the reactor achieved its second longest operating run in its 38-year history, 508 days online, according to Energy Northwest.

The outage work was done with the help of 1,200 temporary workers, many of whom specialize in nuclear plant refueling and maintenance, who supplemented the permanent Energy Northwest staff of about 1,000 workers.

They filled campsites and any available temporary housing near the Tri-Cities this spring.

The Energy Northwest nuclear power reactor is 10 miles north of Richland on leased land at the Hanford nuclear reservation site, but is unrelated to the World War II and Cold War weapons work and ongoing environmental cleanup there.

Columbia Generating Station is a 1,207 megawatt boiling water reactor that provides electricity at cost to the Bonneville Power Administration.

Energy Northwest, which also has wind, solar and hydropower production, comprises 28 public power member utilities, serving more than 1.5 million customers.