Energy Northwest plans to power down its nuclear power plant near Richland for a maintenance outage Sunday.
The Columbia Generating Station is expected to be off the grid for 10 days in an outage that has been coordinated with the Bonneville Power Administration, a nonprofit federal agency that markets power.
The Columbia River, which is used for hydropower production, is running at 110 percent of the annual average, and the nuclear plant outage will reduce the risk of BPA needing to use its oversupply management protocol, said Doug Johnson, BPA spokesman.
BPA already has used the protocol this spring to deal with a surplus of power. The protocol calls for taking thermal generation, such as by coal and gas generation, off the system first, and then usually taking wind generation off the grid, but compensating those producers.
The Columbia Generating Station produces enough power to supply about 1 million homes.
Energy Northwest has planned the maintenance outage to replace a seal on the reactor recirculation pump. It has outages every other year for refueling and the work had been planned for the 2013 refueling outage.
However, Energy Northwest officials have watched the seal degrade over time and decided to take a conservative approach and replace it this spring to ensure reactor reliability, said Energy Northwest spokesman John Dobken.
The recirculation pump puts water through the reactor to produce steam.
Other maintenance work also will be done.
-- Annette Cary: 582-1533; firstname.lastname@example.org