(Reuters) - U.S. nuclear regulators are investigating whether the suspected falsification of documents at French nuclear power company Areva SA, which supplies components for reactors globally, poses any problems at U.S. nuclear plants.

Areva notified the U.S. Nuclear Regulatory Commission (NRC) last week that a review of paperwork “anomalies” at its Le Creusot facility in France “has not found any safety concerns,” NRC spokesman David McIntyre said on Wednesday.

“A preliminary review by NRC inspectors indicated that Areva had made a reasonable assessment supporting no nuclear safety concerns,” McIntyre said. There are nine U.S. plants with parts from Le Creusot, but the NRC did not immediately name them.

There are 99 reactors operating in the United States producing about 20 percent of the nation’s power.

France’s Nuclear Safety Authority, or ASN, requested a probe of Le Creusot in early May after a flaw was discovered in the vessel of a reactor under construction in Flamanville in France.

Areva checked the records of Le Creusot and found anomalies associated with about 400 parts manufactured there since the plant opened in 1965. Areva purchased the forge in 2006.

One U.S. plant with parts from Le Creusot is Dominion Resource Inc’s Millstone station in Connecticut, which has had a pressurizer from the French forge in service in Unit 2 since 2006.

Dominion spokesman Ken Holt said that when Areva manufactured the pressurizer for Millstone they performed some additional heat treatment, but did not tell Dominion.

After Areva informed Dominion about the additional heat treatment in 2016, Holt said Dominion “looked at the documentation and determined there were no operability or functionality issues as a result.”

The pressurizer keeps water in the reactor under pressure so it does not boil.

“We’ve got a component made at a plant with some issues, but we’re confident the pressurizer is fully operational and will remain so through the life of the plant,” Holt said.

Another plant that may be affected is FirstEnergy Corp’s Beaver Valley station in Pennsylvania. Beaver Valley has steam generators and reactor vessel heads manufactured by Spain’s Equipos Nucleares SA, or ENSA, which FirstEnergy said may contain some subcomponents from Le Creusot.

“The audit is still underway but at this point in time there have not been any identified issues with quality or safety of any components at our plants,” FirstEnergy spokeswoman Jennifer Young said.