A special inspection started up at the Grand Gulf nuclear power plant to review events that led to, and occurred following, an unplanned shutdown December 12.
The plant, operated by Entergy Operations, is in Port Gibson, Mississippi.
The plant was operating at full power when operators noticed an unexpected increase in reactor power and decided to shut down as a precautionary measure, said officials at the Nuclear Regulatory Commission (NRC).
The reactor was shut down and remains off-line, but employees continue to work as normal, said Mike Bowling, a spokesman at Entergy.
“(One of the operators) in the control room noticed a turbine bypass valve that was moving a little,” Bowling said. “This valve … was opening and basically moving some. That will impact the pressure in the system.”
The reactor was safely shut down but some equipment issues occurred the agency wants to better understand.
Bowling said it’s not unusual to shut down for maintenance.
“It’s not something they want to do, but they will if it needs to be done,” Bowling said.
There were no safety concerns for the public or employees, Bowling said.
The two-member NRC team will spend about a week on site developing a chronology of the event, and evaluating the licensee’s cause analysis and the adequacy of corrective actions.
An inspection report documenting the team’s findings will be publicly available within 45 days of the end of the inspection.