US NRC Blog Update: Before the Browns Ferry Fire: Antiquated Notions That Electricity and Water Didn’t Mix

 

Before the Browns Ferry Fire: Antiquated Notions That Electricity and Water Didn’t Mix

Browns Ferry Fire: Historical Photo

Few events altered nuclear power regulation as much as the Browns Ferry Unit 1 fire. In March 1975, thousands of electrical cables burned for nearly eight hours disabling all of Unit 1’s and many of Unit 2’s emergency core cooling systems. Only creative action by plant operators prevented reactor damage, and only a resort to water hoses rather than portable fire extinguishers quenched the flames.

The NRC was just two months old when the fire started, and it enacted sweeping reforms to enhance fire detection, prevention, and suppression.

Browns Ferry was so momentous that the fire history before it receives little attention and is dismissed in a few sentences: The NRC’s predecessor, the Atomic Energy Commission, didn’t consider fire a nuclear safety issue. It erred in deferring to non-nuclear standards set by property insurance companies and engineering associations. Such deference was inadequate because insurance standards were designed to limit property damage rather than prevent a reactor accident.

In fact, the fire can’t be so easily blamed on AEC inattention. The agency did believe fire was a safety issue, and it insisted on special fire protection designs that proved inadequate at Browns Ferry. Its key error, then, wasn’t in deferring to non-nuclear fire insurance experts; it sometimes didn’t defer enough. Most egregiously, nuclear regulators rejected expert recommendations on fire suppression systems believing that nuclear safety considerations demanded alternative designs.

By the late 1960s, fire protection experts mostly favored water sprinklers for electrical and electronic fires. Tests and experience showed that CO2 extinguishing systems were inferior to sprinklers in their ability to rapidly smother and cool anything but small fires. Businesses installed sprinklers in diverse applications such as computer factories and electric cable rooms in steel mills. Even AEC weapons plants had them. Fire insurance associations recommended sprinklers throughout civilian nuclear power plants.

AEC regulators and the industry disagreed. Having limited nuclear-specific data on fires, they operated from antiquated notions that electricity and water didn’t mix. They feared water would cause short circuits and disable backup reactor safety systems. With AEC encouragement, new plants commonly installed fixed CO2 systems in electrical areas, as was done in Browns Ferry’s damaged cable spreading room.

David Notley, the NRC’s first fire safety expert, noted the ironic result of the AEC’s ignorance on fire suppression. Believing that nuclear power was a special exception to standard industrial practice, regulators dismissed non-nuclear experience that might have improved reactor fire safety. As another fire protection consultant concluded, a small fire almost destroyed a reactor because existing practices weren’t used.

The AEC did treat fire as a reactor safety threat, but it pursued ill-informed solutions. Chastened by Browns Ferry, the NRC expanded its fire regulations and a launched a fire research program that have measurably improved plant safety. The early regulatory mistakes reverberate today. As one expert observed, the full expense of the Browns Ferry fire is uncertain because the NRC and industry continue to implement fire safety enhancements.

Moderator | June 4, 2013 at 8:49 am | Tags: Browns Ferry, fire protection, history, NRC, nuclear power plant | Categories: Operating Reactors | URL: http://wp.me/p1fSSY-15A