Officials from the Tennessee Valley Authority, which operates the Browns Ferry Plant near Athens, Ala., met with Nuclear Regulatory Commission officials in Atlanta to respond to the federal report on the valve failure. The mechanical problem in the plant's Unit 1 reactor was discovered by TVA employees while the reactor was shut down for refueling in October and reported to the NRC.
TVA officials said the failure was not caused by plant operator error. The failed valve has been repaired and the plant is addressing the problem in similar valves in that reactor and others, officials said.
The NRC had raised concerns that the valve failure could have left a residual heat removal system unable to do its job, particularly in the case of a fire.
Plant operators turned off the valve when they noticed that it wasn't working during the shutdown in October and used another one to perform the necessary function, TVA officials said. But during an accident they would not have turned it off and, according to laboratory tests, the failed valve would have kicked in within seven minutes, TVA officials said.
The NRC has asked TVA to provide answers to other questions, and once it has, the federal regulator will use objective and subjective factors to determine the significance of the failure within 30 days, said NRC regional administrator Victor McCree. If the NRC decides that the failure was significant, it could require additional inspections at Browns Ferry.
"My interest at this point is making sure we have a satisfactory response to the questions that we asked," McCree said. "They were very open with us today, and I have every reason to believe they will continue to be very open in their responses to our questions."
Past problems at the Browns Ferry Plant have at times led to increased NRC oversight. 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.
"We don't want to speculate on the action they'll take," TVA spokesman Ray Golden said. "We'll deal with whatever happens."