Every two years, Energy Northwest takes Columbia Generating Station offline for a refueling outage.
Columbia’s 27th refueling outage (R-27) will begin April 11, 2025 and is scheduled for 56 days.
About 2,000 skilled workers, hired locally and from across the country, join Energy Northwest’s workforce of about 1,000 employees, to support refueling and maintenance projects. For job postings, see our Careers page.
Workers replace about a third of the 764 nuclear fuel assemblies in Columbia’s core with new fuel. Fuel assemblies that have been in the reactor core for six years will be placed in Columbia's used fuel pool, which removes residual heat from the assemblies.
After a minimum of five years in the pool, the used assemblies are moved to Columbia’s on-site dry cask storage, where they are stored securely in above-ground, 185-ton, concrete and steel, dry-storage casks. There are currently 54 casks on site, containing most of Columbia’s 40 years of used fuel.