Energy Northwest disconnected Columbia Generating Station from the Northwest power grid early on June 23 to rebalance its turbines following a recent maintenance outage. 

It was not clear how long the nuclear power plant would be disconnected, with the energy cooperative citing “market sensitivities” in a release, adding that it would be a brief interruption. 

Since reconnecting to the grid last week, staff at the plant have monitored turbine vibration levels as part of the restarting process. When the turbine reached 80% power, vibrations reached a pre-determined setpoint that will require workers to install balance weights to adjust them. 

“Balancing the turbine is a precise process and it’s important for the long-term reliability of our equipment to provide power to the region,” said Bob Schuetz, CEO of Energy Northwest, in a statement. “Following the work, operators will reconnect Columbia to the grid and the turbine will continue to be monitored closely. If vibration levels exceed acceptable parameters, an additional balancing procedure may be required.” 

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.