Prairie Island one of 17 nuclear reactors with parts from French forge under investigation

The U.S. Nuclear Regulatory Commission says 17 U.S. nuclear reactors in 10 states — including Xcel Energy's Prairie Island power plant — include components made at a French forge embroiled in a controversy over quality control and possible record-keeping manipulation.

The forge at Le Creusot, France — currently owned by the French firm Areva — has been making nuclear plant components for decades. It produced most of the steel forgings for the two nuclear reactor vessels at the 44-year-old Prairie Island plant, which is near Red Wing, Minn.

Areva has been under investigation for months by French nuclear regulators, and several reactors in France have been temporarily idled.

"We are confident at this time that there are no safety concerns for [U.S.] nuclear power plants raised by the investigations in France," the NRC said in a statement on Tuesday.

The agency said its "confidence" is based on several factors, including preliminary evaluations of reactor components in France; the NRC's participation in a multinational regulatory inspection at Le Creusot Forge; and information about "documentation anomalies" supplied by Areva.

"Also, the components supplied to U.S. plants have performed well and inspections during their operating life have revealed no safety issues," the NRC said. "Because there are no immediate safety concerns, there is no justification for the NRC to order plants to shut down and inspect components, as some groups have suggested."

With French nuclear regulators scrutinizing Areva, the NRC asked Areva for a list of U.S. plants that contain forgings made at Le Creusot.

Xcel told the Star Tribune in December that while issues in the investigation of Areva are "troubling," there are no safety issues at Prairie Island. The reactor vessels, which house the nuclear reactors, are regularly tested, including for the strength of their steel shells, which are seven to nine inches thick, Xcel said.

Most of the affected plants have steam generators or reactor vessel heads that were made with Le Creusot components. Steam generators convert water into steam from heat produced in nuclear reactors. Vessel heads are the covers for the reactor vessels. Vessel heads at Prairie Island were not made at Le Creusot, though much of the rest of the vessels were.

Questions surrounding Le Creusot Forge surfaced in 2015 when tests of steel components at a French nuclear plant showed carbon concentrations that were beyond acceptable limits. Excess carbon can weaken steel. The components were made at Le Creusot, as were steel parts with high carbon levels at other French reactors inspected by ASN, France's nuclear regulator.

ASN required Areva to review many years of work done at Le Creusot. Areva, a global nuclear plant supplier that has owned Le Creusot Forge since 2006, reported back earlier this year that it had found document irregularities going back to the mid-1960s.