Browns Ferry Nuclear Plant in Athens, Ala., is shown from above.

Federal regulators have removed their harshest finding against TVA's biggest nuclear plant after nearly three years of corrective actions by the federal utility.

But the U.S. Nuclear Regulatory Commission will maintain heightened inspections of the Browns Ferry Nuclear Plant in Alabama due to lingering concerns about operations, maintenance, work planning and equipment reliability at the three-reactor plant.

The NRC issued a "red" finding against TVA in May 2011 after discovering a blocked valve to a key emergency system had been undetected for months at Browns Ferry. Regulators said the broken valve could have prevented TVA from safety shutting down the reactor in the event of a fire or explosion.

The red finding is the most severe assessment against a nuclear plant by regulators short of ordering the plant to shut down. Browns Ferry is among only a handful of nuclear plants to receive a red finding.

In a letter to TVA last week, NRC Regional Administrator Victor McCree said TVA had corrected the valve failure and improved testing and work procedures to avoid a repeat of the problem.

"The NRC has determined that the results of this inspection, in conjunction with the previously completed inspection activities, provided adequate assurance that the completed or planned corrective actions were sufficient to address the performance that led to the red finding," McCree said.

However, NRC officials said Browns Ferry would remain in Column Four in its reactor oversight process action matrix until other plant problems and procedures are resolved. TVA officials say they expect all three units at Browns Ferry to be moved out of the heightened safety category this spring.

"Our ultimate goal is the sustainability of our improvements and really driving the plant to excellence," said Keith Polson, Browns Ferry site vice president. "This really wasn't an exercise to get through the (NRC) inspection. This was really to drive sustained performance improvements that lead to excellence."

Browns Ferry, a GE boiling water reactor with three units, was initially constructed in the 1960s and is TVA's oldest nuclear power plant.

Contact Dave Flessner at dflessner@timesfreepress.com.