OMAHA, Neb. (AP) — A Nebraska environmental group on Monday questioned the track record of the company hired to run the Fort Calhoun nuclear power plant because of concerns raised by federal regulators.

The Clean Nebraska group said it was troubled by the questions the Nuclear Regulatory Commission had raised about some of the calculations Exelon made for its other nuclear plants. The NRC said last week it was looking into whether Chicago-based Exelon intentionally understated the cost of decommissioning 23 of its nuclear reactors.

Exelon spokesman David Tillman said the company denies intentionally providing incorrect data and “disputes the findings.” Tillman said the calculations are complicated and Exelon looks forward to meeting with the NRC to discuss the issue.