Nuclear Regulatory Commission - News Release
No: I-23-003 May 1, 2023
NRC Initiates Special Inspection at Calvert Cliffs Unit 1 Nuclear Power Plant
The Nuclear Regulatory Commission has begun a Special Inspection at the Calvert Cliffs Unit 1 nuclear power plant to review issues associated with an emergency diesel generator at the facility. The twin-engine generator malfunctioned during recent testing and was the subject of an NRC enforcement action last year.
A three-member team arrived at the Lusby, Maryland, plant on May 1 to begin the inspection. The team will be supplemented by the NRC resident inspectors assigned to Calvert Cliffs, who have been following plant owner Constellation Energy’s actions on-site since the mechanical failure of the generator on April 24.
The NRC inspection team will gather key information regarding the problems involving the generator and will seek to better understand plant operators’ response. The team will document its findings in an inspection report to be issued within 45 days following the conclusion of the review.
“Because of redundant systems, this event did not directly impact plant safety,” NRC Region I Administrator Raymond Lorson said. “Nevertheless, our team has been tasked with learning more about why this problem occurred and what steps the company is taking to ensure it does not happen again.”
Operators have determined that the plant’s other emergency diesel generators are unlikely to have similar problems, but NRC inspectors are reviewing that assessment as part of this review.
Emergency diesel generators are considered a key safety component at nuclear power plants. In the event off-site power becomes unavailable, plants use the emergency diesel generators and battery systems to operate safety systems until it is restored.
Last September, the NRC finalized a “white,” or of low to moderate safety significance, inspection finding for Calvert Cliffs based on a problem involving the same emergency diesel generator. In that case, operators failed to prevent the introduction of foreign material into the generator, resulting in its automatic shutdown and failure during routine testing.
