TRAVERSE CITY, Mich. -- Federal regulators said Tuesday that safety violations at the Palisades nuclear power plant in southwestern Michigan had led them to downgrade the plant to a status held by just two others in the U.S.

The Nuclear Regulatory Commission assigns the more than 100 nuclear reactors in the U.S. to one of five categories based on their safety performance. Most are in the top-performing group. Palisades was bumped to the No. 2 category last month and now will join two others in the third category: the Perry Nuclear Power Plant's Unit 1 generator near Cleveland and the Susquehanna Nuclear Power Plant's Unit 1 generator in Berwick, Pa.

The only reactor that ranks lower is Browns Ferry Unit 1 near Athens, Ala., which is in the fourth category.

Palisades' demotion means the plant will get closer scrutiny from regulators and will undergo a team inspection to determine whether staffers understand what caused their violations and have taken steps to prevent them from happening again, Nuclear Regulatory Commission spokeswoman Prema Chandrathil said.

Despite the findings, the commission remains confident the plant does not pose a danger to nearby residents, Chandrathil said.

"If the plant was not operating safely, we would not hesitate to shut them down," she said.

Located in Van Buren County's Covert Township on the Lake Michigan shoreline, Palisades is owned by New Orleans-based Entergy Corp.

Palisades spokesman Mark Savage said the plant was cooperating fully with the commission and had accepted the agency's findings about two violations last year and one in 2009 that caused the downgraded status.

One was a Sept. 25 electrical fault caused by plant workers that caused the reactor and half of the control room indicators to shut down and triggered safety systems that actual plant conditions did not justify, the commission said. Agency investigators described the incident as having "substantial safety significance."

The other was the failure of a water pump that cools safety equipment. It resulted from cracking of one of the couplings that hold together rods in the cooling system. The same failure had happened in 2009, and the commission said an inspection showed the plant hadn't done enough to prevent a recurrence.

The agency designated that event as having "low to moderate" significance.

Savage said Palisades has since replaced all 21 of the couplings, not just the one that failed.

"The things we had violations for were equipment issues or things that happened during maintenance of equipment," he said. "The plant continued to operate safely even when all of these activities were ongoing."

The commission has scheduled a public meeting for Feb. 29 in nearby South Haven to discuss the plant's performance, Chandrathil said.

Beyond Nuclear, an activist group, said the commission should shut down the plant.

"The grass-roots environmental movement of the Great Lakes will do all it can to shine a spotlight on the grave risks at Palisades," said Kevin Kamps, the group's radioactive waste specialist.

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