An equipment malfunction at a substation forced the shutdown of Columbia Generating Station.

Share story

Washington’s lone nuclear plant reconnected to the Northwest power grid late Saturday, six days after an equipment malfunction caused an unplanned shutdown.

Energy Northwest said operators of the Columbia Generating Station, near Richland, have been slowly raising power levels and expect to reach 100 percent within 72 hours of restarting.

The plant shut down at 11:24 p.m. Dec. 18 after a malfunction at the Bonneville Power Administration’s nearby Ashe Substation. The substation handles all the electricity produced at the Richland plant.

The malfunction caused the 500-kilovolt line that connects the plant’s main output transformers to the substation to reject the load. A primary breaker that was supposed to open was slow to do so, but a secondary system kicked in and opened other breakers, causing the plant to separate itself from the grid and shut down.

Most Read Stories

Unlimited Digital Access. $1 for 4 weeks.

Columbia Generating Station is the third-largest power plant in the state. It sends enough power to the Northwest grid to power a city the size of Seattle.