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:
lures in at least three cables. This applies when there are defense-in-depth features, such as automatic suppression and limits on ignition sources and combustibles. When there are no defense-in-depth features, the number of cables to consider should not be limited to two or three as described above. In addition, for multiconductor cables, all circuit faults that could occur within the cable should be assumed to occur. The analysis should address all circuits for which fire-induced failure could prevent safe shutdown, and appropriate protection should be provided. Chapter 3 of industry guidance document NEI 00-01, Revision 4, provides an acceptable deterministic methodology for the analysis of post-fire safe-shutdown circuits, when applied in conjunction with this RG. 5.3.1 Identification and Evaluation of Post-fire Safe-Shutdown Circuits Two classifications of equipment in the plant are important when evaluating the ability to achieve and maintain shutdown during and following a fire. Regulatory Position 5.3.1.1 describes the equipment on the success path necessary to achieve and maintain hot-shutdown conditions. This equipment is a subset of the second and more general set of SSCs important to safe shutdown described in Position 5.3.1.2. These classifications are not applicable to alternative or dedicated shutdown systems credited for post-fire safe shutdown as defined in Appendix R, Section III.G.3. Position 5.4 discusses alternative or dedicated shutdown. The information included in Appendix H to NEI 00-01, Revision 4, may be used in classifying components on the success path required for hot shutdown and those important to safe shutdown, when applied in conjunction with this RG. Note that the NRC will treat the phrase “required for hot shutdown” in NEI 00-01, Revision 4, as having the same meaning as the phrase “the safe-shutdown success path” used in this guide. The post-fire safe-shutdown circuit analysis should address all possible fire-induced