** FILE ** Donald Crabtree, a Tennessee Valley Authority project manager from Stevenson, Ala., leads a media tour around the old Bowling Green, Ky., power plant on Power Street, which was torn down to allow for TVA expansion, on Wednesday Nov. 30, 2011. (AP Photo/Daily News, Alex Slitz)
In a Wednesday, Oct. 19, 2011, file photo, Walter Lee, right, manager of Nuclear Emergency Preparedness, leads the evaluation as the Tennessee Valley Authority conducts an emergency preparedness drill in the Central Emergency Control Center in Chattanooga, Tenn. (AP Photo/Chattanooga Times Free Press, Dan Henry)** FILE **