The Northwest’s only nuclear power reactor will disconnect from the grid early Monday morning after an issue developed following the
plant outage
that ended June 16.
Energy Northwest’s Columbia Generating Station
was expected to start powering down on Sunday before disconnecting from the grid and then addressing the problem.
After the Eastern Washington plant returned to service, turbine vibration readings increased to higher that expected.
As the plant reached 80% power, turbine vibration levels reached a point that require a turbine balancing procedure to reduce vibration and support full-power operation, Energy Northwest said late Sunday afternoon.
Siemens Energy has provided technical guidance, and Energy Northwest workers will install balance weights on the main turbine, Energy Northwest said.
“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, Energy Northwest chief executive officer, in a statement.
The time the plant will be disconnected from the Northwest electric grid is expected to be brief.
Once balancing is done and the plant is back on the grid, the turbine will be closely monitor.
If vibration levels are again too high, an additional balancing procedure may be required, Energy Northwest said.
A similar turbine balance was performed in December 2021 during a planned maintenance outage that also required temporary disconnection from the grid.
Columbia Generating Station’s turbine system includes three low-pressure turbines and one high-pressure turbine, with a combined rotating mass of approximately 1.2 million pounds. Precise alignment and balance are essential for reliable operation, as the turbines drive the main generator to produce electricity for the region.
The plant, which usually supplies enough electricity around the clock to power about 1 million homes, reconnected to the grid about 5 p.m. Monday, June 16, after a 65-day outage for refueling and for maintenance work that cannot be done while the reactor is operating.
Every other spring a third of the fuel rods in the reactor are replaced with fresh fuel.
The 2025 outage for the plant 10 miles north of Richland was longer than usual and the 2,000 workers hired were more than usual due to a major project, installing a new adjustable speed drive system.
The system needed to be replaced after there were a few issues that required powering down to fix components.
The speed drive controls the pumps that control the water inside the core, which in turn controls the amount of
power the reactor produces
, according to Energy Northwest.
The heat produced by a chain reaction boils the water within the core, creating steam that turns turbines attached to an electric generator.
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