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:
ons should be ducted separately from cable runs in ceiling and floor spaces. If cables are routed in underfloor or ceiling spaces, these spaces should not be used as air plenums for ventilation of the control room. 6.1.3 Cable Spreading Room A separate cable spreading room should be provided for each redundant division. Cable spreading rooms should not be shared between reactors. Each cable spreading room should be separated from the others and from other areas of the plant by barriers with a minimum fire rating of 3 hours. If this is not possible, an alternative or dedicated shutdown capability should be provided. Cable spreading rooms should have the following: a. at least two remote and separate entrances for access by fire brigade personnel, b. an aisle separation between tray stacks at least 0.9 m (3 ft) wide and 1.5 m (5 ft) high, c. hose stations and portable extinguishers installed immediately outside the room, and d. area fire detection. If division cables are not separated by 3-hour barriers, separation should meet the guidelines of RG 1.75, and the cables should have a suitable fire-retardant coating. (New reactor cables should meet the fire and flame test requirements of IEEE 1202.) 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 also be provisions to preclude inadvertent operation. Determination of the 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