Energy Northwest’s nuclear power plant north of Richland is once again providing power to the grid after an unplanned shutdown on Feb. 12 to address a problem with its reactor cooling system. 

The Columbia Generating Station, which generates more than 1,200 megawatts of power, was brought back online in the afternoon of Feb. 17, according to a release. During the five-day shutdown, workers completed repairs, performed thorough testing and verified the performance of equipment. 

“From start to finish, we kept safety and operational excellence at the forefront,” said Dawn Sileo, executive vice president and chief nuclear officer, in a statement. “Our team demonstrated strong teamwork, thorough analysis and rigor as we worked to resolve the issue and return the plant to reliable operations.” 

Operators manually shut down the plant after they found issues with the pumps circulating water through the reactor’s core. Technicians found the cause and solution to that issue was straightforward, Energy Northwest spokeswoman Kelly Rae told the Tri-Cities Area Journal of Business.  

The shutdown was caused by a small failed electrical filter in the plant’s adjustable speed drive glycol system.  

“That system cools the adjustable speed drives, which control the reactor recirculation pumps,” Rae said. “When the cooling was lost, both pumps tripped offline, and operators manually shut down the plant.” 

Columbia Generating Station had not had an unplanned outage in nearly a decade. The power plant was last offline for its routine refueling process nine months ago. A week after it was reconnected to the grid, operators disconnected it for several days to rebalance its turbines.