Document: NRC Regulatory Guide
Document ID: 80776ca5-a83d-4667-9a94-0bffa1befa91
Document Type: regulatory_guide
Title: Fire Protection Guidelines for Nuclear Power Plants (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1221/ML12216A013.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.120
CFR Part: 
CFR Title: 

Content:
sed with any other plant system alarms. (6) Primary and secondary power supplies should be provided for the fire detection system and for electrically operated control valveb for automatic suppression systems. Such primary and secondary power supplies should satisfy provisions of Section 2220 of NFPA 720. This can be accomplished by: (a) Using normal offsite power as the primary ,upply with a four-hour battery supply as secondary supply; and (b) Having capability for manual connection to the Class lE emergency power bus within four hours of loss of offsite power. Such connection should follow the applicable guide- lines in Regulatory Guides 1.6, 1.32, and 1.75. b. Fire Protection Water Supply Systems -(l) An underground yard fire main loop should be installed to furnish anticipated water requirements. NFPA 24, "Standard for Outside Protection," gives necessary guidance for such installation. It references other design codes and standards developed by such organiza- tions as the American National Standards Institute (ANSI) and the American Water Works Associa- tion (AWWA). Type of pipe and water treatment should be design considerations with tuberculation as one of the parameters. Means for inspecting and flushing the systems should be provided. Approved visually indicating sectional control valves such as post indicator valves should be provided to isolate portions of the main for maintenance or repair without shutting off the supply to primary and backup fire suppression systems serving areas that contain or expose safety- related equipment. The fire main system piping should be separate from service or sanitary water system piping, except as described in Regulatory Position C.5.c.(4). 1.120-14 (2) A common yard fire main loop may serve multi-unit nuclear power plant sites if cross-connected between units. Sectional control valves should permit maintaining independence of the individual loop around each unit. For such installations, common water supplies may also