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:
roximately once in 10 years), such as tornadoes, hurricanes, floods, ice storms, or small-intensity earthquakes that are characteristic of the geographic region, and (2) potential manmade site-related events, such as oil barge collisions or aircraft crashes, that have a reasonable probability of occurring at a specific plant site. For water suppression systems and fire detection systems that use metal plates for heat collection above individual sprinkler heads or detectors that are located well below the ceiling of a fire area (e.g., at some intermediate height in the room, below a ceiling-mounted pipe and cable tray), licensees should demonstrate that this design will ensure acceptable actuation times. In general, the use of such plates has not been shown to provide adequate heat collection to effectively activate the sprinkler head or detector and may impair system response. 3.3.1 Water-Based Fire Suppression Systems Equipment important to safety that does not itself require protection by water-based suppression systems, but is subject to unacceptable damage if wetted by suppression system discharge, should be appropriately protected (e.g., water shields or baffles). Drains should be provided as required to protect equipment important to safety from flooding damage. 3.3.1.1 Sprinkler and Spray Systems Water sprinkler and spray suppression systems are the most widely used means of implementing automatic water-based fire suppression. Sprinkler and spray systems should conform to requirements of appropriate standards such as NFPA 13 and NFPA 15. 3.3.1.2 Water Mist Systems Water mist suppression systems may be useful in specialized situations, particularly in those areas where the application of water needs to be restricted. Water mist systems should conform to appropriate standards, such as NFPA 750, “Standard on Water Mist Fire Protection Systems” (Ref. 79). 3.3.1.3 Foam-Water Sprinkler and Spray Systems Certain fires, such as those involving flammable liquids,