Document: NRC Regulatory Guide
Document ID: 8e45dce1-e1e7-4415-b1dd-7e2a610e545b
Document Type: regulatory_guide
Title: Fire Protection for Nuclear Power Plants (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2023/ML20231A835.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.189
CFR Part: 
CFR Title: 

Content:
nd stairways, plant locations on either side of such a barrier should be considered part of a single fire area. If success path A is separated by a cumulative horizontal distance of 6.1 m (20 ft) from success path B, with no intervening combustible materials or fire hazards, and both elevations are provided with fire detection and suppression, the area would be considered acceptable. Exterior walls, including penetrations, should be qualified as rated fire barriers if they are required to separate safe-shutdown equipment on the interior of the plant from the redundant equipment DG-1359, Page 60 located in the immediate vicinity of the exterior wall, if they separate plant areas important to safety from nonsafety-related areas that present a significant fire exposure to the areas important to safety, or if otherwise designated by the FSAR or fire hazards analysis. An exterior yard area without fire barriers should be considered as one fire area. The area may consist of several fire zones (see Regulatory Position 4.1.2.2 of this guide). 4.1.2.2 Fire Zones Fire zones are subdivisions of a fire area and are typically based on fire hazards analyses that demonstrate that the fire protection systems and features within the fire zone provide an appropriate level of protection for the associated hazards. Fire zone concepts may be used to establish zones within fire areas where further subdivision into additional fire areas is not practical on the basis of existing plant design and layout (e.g., inside containment). Evaluations by some licensees made before Appendix R to 10 CFR Part 50 was published were based on fire zones that do not meet the strict definition of fire areas. In some cases, the separation of redundant success paths within the fire zone boundaries and the separation between fire zones do not comply with the separation requirements of Appendix R. Such configurations may be acceptable under the exemption process. An exterior yard area considered as one fire