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.