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

Nuclear regulators have slapped another citation against the Tennessee Valley Authority at its Browns Ferry nuclear plant, but officials said the violation last December was of "low to moderate significance."

The U.S. Nuclear Regulatory Commission today issued a "white" finding for an unplanned emergency shutdown at Browns Ferry and the failure of a nuclear operator to follow property procedures. The finding is the lowest among the four levels of the NRC's color-coded warning system.

In a meeting with the NRC in July, TVA argued against the finding based upon its statistical modeling for risk and significance for such a shutdown.

The finding won't result in any intensified oversight by regulators since Browns Ferry is already operating under heightened review because of a more serious "red "finding that stemmed from the 2010 discovery of a blocked emergency cooling line in a key safety system at Browns Ferry that TVA was apparently unaware of for the previous 18 months.

NRC said in a statement today it will conduct supplemental inspections to ensure TVA understands the cause and extent of the problem that led to the white finding.

"Following procedures is extremely important in nuclear power plants and TVA is making changes in the way procedures are implemented to provide the right checks and balances," NRC Regional Administrator Victor McCree said. "We will review those changes to make sure the underlying issues have been addressed in a comprehensive way."

NRC officials still rank the Unit 1 reactor at Browns Ferry as one of the worst performing nuclear plants in the country. Federal officials will rely on the results of future inspections and reviews to determine whether they upgrade the plant's rating, which affects the level of NRC scrutiny it receives.