The U.S. Nuclear Regulatory Commission will decide late next month whether to lift or extend a rare "red-level" safety finding—in place since 2011—at the Browns Ferry nuclear plant in Athens, Ala., after a 24-in.-dia valve in a cooling system failed to open in one unit. The malfunction could have impeded unit core-cooling in a fire. The ruling follows a multi-phase NRC inspection, the latest part occurring last month, that has identified safety problems and spurred corrective actions at the site by the owner, Tennessee Valley Authority.

The 2011 NRC citation, something not issued by the agency since 2003, is just short of ordering a plant shutdown, says William Jones, deputy regional director in the agency's division of reactor projects. He says the faulty Unit 1 valve could have been malfunctioning for many months.

Browns Ferry, which came on line in the 1970s, is only the fifth nuclear plant to receive a red-level citation. The 1,100-MW unit, shut down in 1985, was restarted in 2007 after a $1.8-million upgrade. Two other site units, each also 1,100 MW, were restarted in the 1990s.

In May, NRC broadened its inspection to analyze if TVA's processes and procedures could cause other serious problems at the plant. The agency's 23-member team reviewed TVA's safety procedures, operations and fire-safety risk caused by the valve malfunction, Jones says. NRC looked at plant engineering, maintenance, management governance and its "safety-conscious" work environment, according to Jones. NRC has concerns about the plant's safety culture and the willingness of its workers to report issues and challenge decisions, he adds.

Inspectors will determine whether TVA corrective actions since 2011 have been enough to overcome deficiencies and achieve long-term improvement. "We're not where we want to be, but we are making progress and headed in the right direction," says utility spokesman Mike Bradley. The federal power producer has allotted $138 million this fiscal year for new safety systems and improved staff training, he adds.