Energy Northwest’s nuclear power plant is once again contributing power to the grid after going offline to address vibration levels on its turbines after being worked on earlier this spring. 

Columbia Generating Station was brought back online on June 29 after a weeklong outage to install balance weights in its turbine system, according to a release. With a combined rotating mass of 1.2 million pounds, precise alignment and balance are necessary to maintain optimal and reliable operation. 

The plant was recently offline for two months as workers refueled, upgraded and performed maintenance at the facility, which is the third-largest power supplier in the region. When the turbine reached 80% power following that work, vibrations reached a pre-determined set point that required workers to install balance weights to adjust them. 

Prior rebalances have been needed following maintenance outages, which occur every two years to allow the plant to refuel as well as repair and upgrade the plant. The last rebalance occurred in December 2021.