The six-day shutdown started after a warning from transformers.

Share story

The Columbia Generating Station, the region’s only nuclear power plant, went back online Thursday morning after a six-day shutdown.

The power plant, which can generate 1,207 megawatts of electricity, shut down Friday after transformers, “sensing an issue,” disconnected from the transmission system, according to a written statement from Energy Northwest, the plant’s operator.

The transformers’ action initiated a signal that resulted in the plant going offline.

An Energy Northwest spokesperson said they would not know the reason for the disconnect until the relay, which has been sent offsite for analysis, has been inspected.

Energy Northwest officials said that the shutdown did not pose any safety risks.

The Energy Northwest plant, 10 miles north of Richland, is the third-largest generator of electricity in Washington state. The power is sold to the Bonneville Power Administration, and 92 Northwest utilities receive its output.

This was the plant’s third unscheduled shutdown since December 2016.