Document: NUREG-0800
Document ID: 05a851a6-07ff-41b4-8528-a032ba433e04
Document Type: srp
Title: FIRE PROTECTION PROGRAM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0327/ML032740044.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.5.1
CFR Part: 
CFR Title: 

Content:
e provided to minimize the adverse effects of fires on structures, systems, and components important to safety. However, during this early stage of nuclear power regulation, given the lack of detailed implementation guidance for this general design criterion, the level of fire protection was generally found to be acceptable if the facility complied with local fire codes and received an acceptable rating from its fire insurance underwriter. Thus, the fire protection features installed in early U.S. nuclear power plants were very similar to those installed in conventional fossil-fuel power generation stations. A fire at the Browns Ferry Nuclear Power Plant, Unit 1, on March 22, 1975, was a pivotal event that brought fundamental change to fire protection and its regulation in the U.S. nuclear power industry. The fire started when plant workers in the cable spreading room used an open flame (i.e., a candle) to test for air leakage through a non-fire-rated (polyurethane foam) penetration seal that led to the reactor building. The fire ignited both the seal material and the electrical cables that passed through it, and burned for almost 7 hours before it was extinguished using a water hose stream. The greatest amount of fire damage actually occurred on the reactor building side of the penetration, in an area roughly 12.2 m (40 feet) by 6.1 m (20 feet). More than 1600 cables, routed in 117 conduits and 26 cable trays, were affected and, of those cables affected, 628 were important to safety. The fire damage to electrical power, control systems, and instrumentation cables impeded the functioning of both normal and standby reactor cooling Revision 4 - October 2003 5 systems and degraded plant monitoring capability for the operators. Given the loss of multiple safety systems, operators had to initiate emergency repairs in order to restore the systems needed to place the reactor in a safe shutdown condition. The investigations that followed the Browns Ferry fire identified