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:
uipment in any one fire area (except for the control room and containment) will be rendered inoperable by fire and that reentry into the fire area for repairs and operator actions is not possible (see Regulatory Position 8.2 of this guide). The control room is excluded from this approach, provided that the design includes an independent alternative shutdown capability that is physically and electrically independent of the control room. Designs incorporating reactor containment buildings should provide fire protection for redundant shutdown systems in the reactor containment building that will ensure, to the extent practicable, that at least one post-fire shutdown success path will be free of fire damage. The safe-shutdown analysis should evaluate a fire in each fire area containing SSCs important to safety and identify a post-fire safe-shutdown success path. The analysis should also identify all fire-induced circuit failures that could directly or indirectly (e.g., by causing spurious actuations) prevent safe shutdown. There is no regulatory requirement to prevent the fire-induced failure of redundant systems necessary to mitigate the consequences following design-basis accidents if the system is not required to operate to achieve safe shutdown after a fire. However, the licensee is required to prevent (or mitigate, where permitted by regulatory requirements) fire-induced failures of these systems if the failure DG-1359, Page 75 could prevent safe shutdown (e.g., because of spurious actuations). The most stringent fire damage limit should apply to those systems that fall into more than one category. For the application of fire protection regulatory requirements, redundant trains of systems may be two or more similar trains of equivalent capacity in the same system powered by separate electrical divisions, or they may be two or more separate systems designed to perform the same post-fire safe-shutdown function. In cases where the regulatory requirements for