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:
aration 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 area may consist of several fire zones. The fire hazards analysis should be used to determine the boundaries of the fire zones. The protection for redundant, alternative, or dedicated shutdown systems within a yard area should be determined on the basis of the largest postulated fire that is likely to occur and the resulting damage. The boundaries of such damage should be justified with a fire hazards analysis. The analysis should consider the degree of spatial separation between divisions; the presence of in situ and transient combustibles, including vehicular traffic; grading; available fire protection; sources of ignition; and the vulnerability and criticality of the shutdown-related systems. 4.1.2.3 Access and Egress Design The plant layout should provide adequate means of access to all plant areas for manual fire suppression. The plant layout should also allow for safe access and egress to areas for personnel performing safe-shutdown operations. Considerations should include fire and post-fire habitability in safe-shutdown areas, protection or separation from fire conditions of access and egress pathways to safe-shutdown SSCs, and potential restrictions or delays to safe-shutdown area access potentially caused by security locking systems. Stairwells outside primary containment serving as escape routes, access routes for firefighting, or access routes to areas containing equipment necessary for safe shutdown should be enclosed in masonry or concrete towers with a minimum fire rating of 2 hours and self-closing Class B fire doors. Fire exit routes should be clearly marked. Prompt emergency ingress into electrically locked areas by essential personnel should be ensured through the combined use and provision of the following features: DG-1359, Page 61 a. reliable and