The Nuclear Regulatory Commission has cited Dominion, the owner of the Millstone Power Station in Waterford, for a violation after two different contract workers recently provided wrong information about past arrests in background checks.

As part of any U.S. nuclear power plant's Access Authorization program, workers provided with unescorted access privileges to the site must undergo background checks, which involve filling out personal history forms, said Neil Sheehan, spokesman for the NRC, in an e-mail.

The company is responsible for all workers, whether employed directly by Dominion or contracted out through another firm, he said.

In a report issued publicly Friday following probes begun in March, James W. Clifford, the NRC's acting director of the division of Reactor Projects, found one contract worker's falsifying of information to be deliberate. That incident occurred on Feb. 9, when the contract employee failed to report a December 13, 2009, arrest and later admitted knowing it should have been reported.

A second contract worker failed to report being detained. On Feb. 10, the contract employee indicated to a supervisor that he/she had been detained by police on Dec. 27, 2009, but did not believe this amounted to an arrest that was required to be reported. The NRC found that detention should have been reported.

In its report, the NRC said it would treat the two incidents as a single Severity Level IV violation since one was not willful. A "level IV" violation reflects that the incidents were considered to be of "very low safety significance."

That's because the workers were not directly employed by Dominion, the actions appeared to be isolated and not the result of poor management oversight, and Dominion identified the incidents on its own. The company also took actions to correct each situation by banning the employees from the site and taking steps to ensure such problems don't recur, the report states.

Neither the NRC or Dominion identified the contractors.

"We were satisfied with the way Dominion addressed it, but nevertheless it rises to the level that we are going to issue them a violation," said Sheehan. "They have to have a robust access authorization program."

Dominion said it immediately removed the contract workers' unescorted access as soon as the false information was discovered and conducted its own investigations.

"We take any violation like this very seriously," said spokesman Ken Holt.

More than two years ago, a similar incident occurred when a contract worker gained access to the nuclear power facility during a Feb. 19, 2008, shutdown for refueling of the Unit 2 reactor by falsifying a criminal history self-disclosure form. That person did the same thing on a personnel history questionnaire for the Unit 3 reactor outage on Sept. 30, 2008, the NRC said in 2009.

The NRC cited Dominion for that incident in December 2009. The person was banned from working at Millstone.