ATLANTA (AP) — Federal regulators are investigating whether workers at a factory that supplies parts to nuclear plants broke quality control rules and falsified records, according to regulatory filings.

A dozen workers at the Shaw Modular Solutions facility in Lake Charles, La., admitted to a manager that they sometimes entered the identification codes for other workers while recording who performed welds, according to the company’s legal filings. The filings do not offer further details on the incident. The NRC would not comment on the ongoing probe, but its rules state that only a worker who performs a weld can document that it was completed, agency spokesman Scott Burnell said.