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:
gases or other potentially energetic sources (e.g., chemical treatment systems, ion exchange columns, high-voltage electrical equipment) should be listed. l. The availability of oxygen (e.g., inerted containment) should be identified. m. Alternative or dedicated shutdown capability for those fire areas where adequate separation of redundant safe-shutdown systems cannot be achieved should be identified. The analysis should assume fire initiation at the location within each fire area or zone that will produce the most severe fire with the potential to adversely affect SSCs important to safety. Fire development should consider the potential for involvement of other combustibles, both fixed and transient, in the fire area. Where automatic suppression systems are installed, the analysis should evaluate the effects of the assumed fire, with and without actuation of the automatic suppression system. “Worst-case” fires need not be assumed to be concurrent with nonfire-related failures in safety systems, other plant accidents, or the most severe natural phenomena. On multiple-reactor sites, unrelated fires in two or more units need not be assumed to occur simultaneously. The analysis should consider fires involving facilities shared between units and fires DG-1359, Page 19 caused by manmade site-related events that have a reasonable probability of occurring and affecting more than one reactor unit (such as an aircraft crash). The fire hazards analysis should separately identify hazards and provide appropriate protection in locations where losses of SSCs important to safety can occur as a result of the following: a. concentrations of combustible contents, including transient fire hazards of combustibles expected to be used in normal operations, such as refueling, maintenance, and modifications; b. continuity of combustible contents, furnishings, building materials, or combinations thereof in configurations conducive to fire spread; c. exposures to fire, heat, smoke, or