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:
ain loop should be installed to furnish anticipated water requirements. NFPA 24 provides appropriate guidance for such an installation. NFPA 24 references other design codes and standards developed by such organizations as ANSI and the American Water Works Association. The following specific criteria should be addressed: a. The type of pipe and water treatment are design considerations, with tuberculation as one of the parameters. b. The means for inspecting and flushing the fire main are provided. c. Sectional control valves should be visually indicating (e.g., post indicator valves). d. Control and sectionalizing valves in fire mains and water-based fire suppression systems are electrically supervised or administratively controlled (e.g., locked valves with key control, tamper-proof seals). The electrical supervision signal indicates in the control room. All valves in the fire protection system are periodically checked to verify position. e. The fire main system piping is separate from service or sanitary water system piping, except as described in Regulatory Position 3.2.1 of this guide, with regard to providing a seismically designed water supply for standpipes and hose connections. f. A common yard fire main loop may serve multiunit nuclear power plant sites if cross-connected between units. Sectional control valves permit independence of the individual loop around each unit. For multiple-reactor sites with widely separated plants (approaching 1.6 kilometer (km) (1 mile (mi) or more)), separate yard fire main loops are used. g. Sectional control valves are provided to isolate portions of the fire main for maintenance or repair without shutting off the supply to primary and backup fire suppression systems serving areas that contain or expose equipment important to safety. h. Valves are installed to permit isolation of outside hydrants from the fire main for maintenance or repair without interrupting the water supply to automatic or manual fire suppression