TVA's Brown Ferry Nuclear Plant, site of a 1975 fire that was one of the industry's worst accidents, still is in violation of fire safety standards, according to a Nuclear Regulatory Commission letter released Wednesday.

NRC Regional Commissioner Luis A. Reyes said plant inspections this year found that Browns Ferry violated four safety standards.

"The inspection team identified potential violations associated with an inadequate fire response procedure, inadequate compensatory measures and inadequate emergency lighting," Mr. Reyes said in a letter to TVA's top nuclear officials this week.

Regulators developed those standards partly in response to a fire started by a candle that damaged the Unit 1 reactor two years after it began operating in 1973.

NRC officials said none of the newly identified deficiencies presents an immediate safety risk, since TVA has maintained fire watches and other compensatory measures in response to identified weaknesses.

TVA spokesman Craig Beasley said the federal utility is working with regulators to address their concerns and to verify the reliability of plant systems.

"Ultimately, we are going to do the work necessary to implement the National Fire Protection Association standards at Browns Ferry," Mr. Beasley said.

NRC spokesman Roger Hannah said regulators will detail their findings in early December, which could lead to a civil penalty against TVA.

"These are not the kind of issues that would cause us to shut the plant down, but they are issues that TVA will have to address," he said.

Edwin Lyman, senior scientist for the Union of Concerned Scientists, said most of America's 103 reactors were designed before the NRC adopted its current fire safety standards. He said most don't possess the desired cable separation and firewalls between parts of the plants.

"Almost no plants meet all of the NRC's physical standards, but the regulators have allowed plants to use manual steps like fire watches and walk-downs to compensate for the inadequate plant design," he said. "For a long time, the NRC was not issuing violations for fire safety issues. But lately the commission seems more determined to enforce these rules, which we believe is long overdue."

Nuclear critics said the lingering fire safety violations raise questions about TVA's operation of its oldest nuclear facility.

"Browns Ferry was the poster child for real fire concerns in this industry, and we would hope after all these years that TVA would be in compliance with the NRC standards," said Stephen Smith, executive director for the Southern Alliance for Clean Energy. "The fire risk may appear low, but there is no room for error in running a nuclear plant."

The NRC developed its current standards nearly three decades ago. They require more firewalls and other separations between electrical cables and other safety systems.

To compensate at pre-existing Browns Ferry units, TVA has installed fire detection and lighting equipment and regularly does plant walk-downs to detect any hint of fire.

When the NRC found that such compensatory measures also were inadequate at Browns Ferry earlier this year, TVA pledged to bring the plant under National Fire Protection Association standards.

Such a change could exempt TVA from all equipment standards for fire safety in parts of the plant where the utility can demonstrate there is no risk of a fire that might damage plant safety systems.