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 electrical raceways in such underfloor and ceiling spaces, if over one square foot in cross-sectional area, should have automatic fire suppression inside. Area automatic fire suppression should be provided for underfloor and ceiling spaces if used for cable runs unless all cable is run in 4-inch or smalle) steel conduit or the cables are in fully enclosed raceways internally protected by automatic firn suppression. c. Cable Spreading Room The primary fire suppression in the cable spreading room should be an automatic water system such as closed-head sprinklers, open-head deluge system, or open directional water spray system. Deluge and open spray systems should have provisions for manual operation at a remote station; however, there should be provisions to preclude inadvertent operation. Location of sprinkler heads or spray nozzles should consider cable tray arrangements and possible transient combustibles to ensure adequate water coverage for areas that could present exposure hazards to the cable system. Cables should be designed to allow wetting down with water supplied by the fire suppression system without electrical faulting. Open-head deluge and open directional spray systems should be zoned. The use of foam is acceptable. Automatic gas systems (Halon or C02 ) may be used for primary fire suppression if they are backed up by a fixed water spray system. Cable spreading rooms should have: (1) At least two remote and separate entrances for access by fire brigade personnel; (2) An aisle separation between tray stacks at least 3 feet wide and 8 feet high; (3) Hose stations and portable extinguishers installed immediately outside the room; (4) Area smoke detection; and (5) Continuous line-type heat detectors for cable trays inside the cable spreading room. Drains to remove firefighting water should be provided. When gas systems are installed, drains should have adequate seals or the gas extinguishing systems should be sized to compensate for losses through the