The Nuclear Regulatory Commission has downgraded the Palisades nuclear power plant in southwestern Michigan after an investigation of two incidents last year that raised safety concerns.
The NRC notified the plant Tuesday of its decision.
The agency groups nuclear plants into one of five regulatory columns depending on their performance, with the fifth category being the worst. Palisades was bumped from the second to the third column.
The Kalamazoo Gazette reports that Palisades is one of only four plants in the nation in either the third or fourth columns. None are in the fifth.
Palisades spokesman Mark Savage tells The Associated Press the violations that caused the NRC investigation involved equipment or maintenance. He says the plant is operating safely.
Palisades is owned by New Orleans-based Entergy Corp.