Scriba, NY-based Nine Mile Point Unit 1 reactor shut down automatically Tuesday.
The shutdown was the result of a high neutron flux in the plant’s reactor, said officials at the Nuclear Regulatory Commission (NRC). Officials with Constellation Energy Nuclear Group, the plant’s owner, originally thought the turbine that spins to make electricity had tripped.
The cause of the condition is still under review. All plant safety systems responded as designed and there were no complications.
NRC resident inspectors assigned to Nine Mile Point monitored the shutdown and they will review the company’s evaluation of what happened and any corrective actions.
Unit 1 had been at 100 percent power when the shut down occurred. Lyon said plant personnel are working to identify the cause of the shut down and will determine what, if any, repairs or actions will be required.
Meanwhile, Unit 2 is shut down because of a decrease in condenser vacuum levels, officials said.
When a plant is up and running online, vacuum conditions remain in the condenser to maximize efficiency as steam that passed through the turbine cools down to condense it back into water, NRC officials said. The decrease in vacuum levels was the result of a failure of a steam regulator.
The cause of the loss of the primary and backup sources of sealing steam is under investigation.