Because of a decrease in condenser vacuum levels at the Nine Mile Point Unit 2 nuclear power plant, the reactor shut down early Thursday, 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, Nuclear Regulatory Commission (NRC) officials said. The decrease in vacuum levels was the result of a failure of a steam regulator.
All control rods inserted and the plant shut down as expected. The cause of the loss of the primary and backup sources of sealing steam is under investigation.
Unit 1 continues to operate at full power and this shutdown did not have an impact on the reactor.
A NRC official called the shutdown “uncomplicated.” The NRC’s Senior Resident Inspector assigned to the Scriba, NY-based Nine Mile Point responded to the plant’s control room and did not identify any concerns with operator response or equipment performance.
Meanwhile, spent fuel at Nine Mile Point Nuclear Station units 1 and 2 will start to go in storage sites on the grounds surrounding the power plants this summer, said Constellation Energy Nuclear Group (CENG), owner of the two units.
The highly radioactive spent fuel, formerly used in the power plant reactors, will go from the circulating-water spent fuel pool to on-site dry cask storage facilities starting Aug. 26.
Transportation of the spent fuel to the dry cask storage facilities by CENG personnel would take two weeks, said Jill Lyon, a spokeswoman for CENG.
“(Personnel) will be going through a very detailed training process before performing the work,” Lyon said.
CENG built the storage facilities in 2009 for $50 million, said Neil Sheehan, a NRC spokesman.
After use in the reactor, the spent fuel moves to the spent fuel pool which is the size of an Olympic swimming pool and 40 feet deep, Sheehan said. The fuel assemblies go in stainless steel racks below 20 feet of water, which will ensure the radiation is at an acceptable level. The spent fuel must stay in the pool to cool for five years before it can move out of the structure.