​​​Refueling outages at Columbia Generating Station take place once every two years. 

​​​​​​​​Columbia’s 25th refueling outage (R-25) took place May 8 -June 19, 2021. 

About 1,450 skilled workers, were hired locally and from across the country, and joined Energy Northwest’s workforce of about 1,000 employees, to support refueling and maintenance projects. 

Workers replaced 260 of 764 nuclear fuel assemblies in Columbia’s core with new fuel. Fuel that had been in the reactor core for six years was placed in the 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 38 years of used fuel.

Maintenance projects​ completed during R-25 (spring 2021)

• Replaced a low pressure turbine rotor
• Replaced reactor water cleanup heat exchangers and piping 
• Refurbished a condensate pump and motor
• Replaced a service water pump and motor
• Cleaned and inspected the circulating water basin and piping
•​ Replaced a reactor recirculating pump​