CHATTANOOGA, Tenn. (AP) — The failure of a reactor coolant valve at the Tennessee Valley Authority's Browns Ferry Nuclear Plant months ago has raised questions about apparent violations of Nuclear Regulatory Commission requirements.NRC Atlanta region spokesman Joey Ledford said Thursday that the valve was stuck shut. Although there is a separate reactor cooling system, there are scenarios when "this particular system would need to be operable," he said.An NRC statement said TVA has been called to a Monday meeting in Atlanta to explain the safety significance of the valve failure that TVA and the NRC discovered last fall during a shutdown of the Unit 1 reactor at the Browns Ferry Plant near Athens, Ala. The statement said the valve "would have been unable to fulfill its safety function if it had been needed."David Lochbaum, nuclear program director for the Union of Concerned Scientists, said Thursday that for most accidents the valve problem was inconsequential but not in a fire."Had there been a fire at the plant there would have been an inability to cool the core," Lochbaum said in a telephone interview. "Had there been a fire, the fire would have taken out all the backups."Lochbaum, who previously worked at the Browns Ferry plant and last week testified before congressional panels about the industry, said the valve failure was not TVA's fault but was due to testing procedures used at all nuclear plants. He said the testing method used to show that the valve is not working correctly will change."It is something TVA will do different and probably everybody else will do differently," Lochbaum said.TVA nuclear spokesman Ray Golden said Thursday that the mechanical problem at Browns Ferry was discovered, repaired and reported during a Unit 1 refueling shutdown at the three-reactor plant and was never a safety threat. Golden said there are separate reactor cooling systems. He said the valve that circulates cooling water in and out of the reactor was "sort of stuck in the closed position."Golden said the valve failure could result in increased NRC oversight at TVA's' historically problem-plagued plant.Ledford said the Monday meeting would give the NRC "an opportunity to get their side of what happened." He said the NRC would issue a response within a few weeks of the meeting. Ledford said the NRC doesn't regularly impose civil penalties on nuclear plant operators, but the cost of any increase in NRC inspections is paid by the operator.The NRC statement said the meeting is to discuss "apparent violations of NRC requirements linked to the failure of a low pressure coolant injection valve."Ledford said the Monday meeting about the valve failure is not related to the NRC's review of all nuclear plants following the nuclear emergency in Japan.Golden said past problems at the Browns Ferry Plant have at times led to extra NRC scrutiny. The plant is internationally known in the industry as the site where a worker using a candle to check for air leaks in 1974 started a fire that disabled safety systems.TVA had allowed a recent media tour at the plant, which has a reactor design similar to the reactors in Japan that malfunctioned after a magnitude 9.0 earthquake and tsunami. TVA has said the Browns Ferry Plant was designed to withstand a 6.0-magnitude quake. The Knoxville-based utility's nuclear plants in Tennessee — Watts Bar at Spring City and Sequoyah at Soddy-Daisy — are designed to withstand a 5.8-magnitude quake.TVA, the country's largest public utility, supplies power to about 9 million people in Tennessee, Alabama, Mississippi, Kentucky, Georgia, North Carolina and Virginia.