Five of the 75 U.S. nuclear power plants have received red findings for serious violations. The NRC has lifted the red findings on all but TVA's Browns Ferry plant.
Indian Point Unit 2, July 2001. The licensee did not identify and correct stress corrosion cracking in steam generator tubes.
Point Beach, both units, February 2002. Plant workers identified a potential failure of the auxiliary feedwater pumps due to operator procedures.
Davis Besse, September 2002. The utility failed to properly implement the boric acid control and the corrective action programs, which allowed a hole to open up in the reactor vessel head.
Point Beach, Unit 2, March 2003. The utility didn't implement proper design processes or support safety evaluations.
Browns Ferry, Unit 1, May 2011. TVA didn't detect a malfunctioning valve that could have jeopardized the shut down of the plant.
Federal regulators have begun one of the most exhaustive reviews of a TVA operating nuclear plant to determine if the federal utility has corrected problems that led to one of the most severe sanctions against any plant.
The U.S. Nuclear Regulatory Commission, which issued a red finding for safety violations at TVA's Browns Ferry Nuclear Plant two years ago, has assembled nearly two dozen inspectors to review improvements made at the North Alabama plant.
"This is the most comprehensive type of review we do of any existing plant," NRC spokesman Joey Ledford said of the inspection, known as a 95003 review.
TVA requested the review last month in a letter to the NRC. TVA nuclear officials said they believe TVA has addressed concerns that led to the red finding in 2011.
NRC red-flagged the Browns Ferry plant -- only the fifth nuclear plant to ever receive such a citation -- after TVA found a defective valve had gone undetected for years at Browns Ferry's Unit 1 reactor.
Ledford said the NRC will likely conduct on-site inspections at Browns Ferry this spring. The other four nuclear plants red-flagged by the NRC ultimately were removed from the sanctions after such inspections.
TVA spokesman Mike Bradley said TVA has upgraded procedures, training and equipment over the past two years to comply with NRC rules.
"While many of the actions are ongoing, we believe that we have made solid progress in addressing the underlying causes that contributed to the valve failure and are ready for the NRC to come in for the inspection," Butler said.
Dave Lochbaum, a former Browns Ferry nuclear plant worker who now serves as director of the Union of Concerned Scientists Nuclear Safety Project, said the NRC review should identify outstanding problems at Browns Ferry.
"I'm encouraged that TVA is moving to come into compliance with fire protection rules, which have created problems in the past at Browns Ferry," he said.
A March 1975 fire that started at Browns Ferry when a worker was using a candle to search for air leaks was one of the worst nuclear accidents in the United States prior to the 1979 accident at the Three Mile Island plant.