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:
te 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, respond well to foam suppression. Licensees should consider the use of foam sprinkler and spray systems, which should conform to appropriate standards, such as NFPA 16, “Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems” (Ref. 80), and NFPA 11, “Standard for Low-, Medium-, and High-Expansion Foam” (Ref. 81). DG-1359, Page 50 3.3.2 Gaseous Fire Suppression Systems Gaseous systems should be evaluated for potential impacts on the habitability of areas containing equipment important to safety where operations personnel perform safe-shutdown actions or where firefighting activities may become necessary. Where gas suppression systems are installed, openings in the area should be adequately sealed or the suppression system should be sized to compensate for the loss of the suppression agent through floor drains and other openings (see also Regulatory Position 4.1.5 of this guide). The design of gaseous suppression systems should consider the following, as applicable: a. the minimum required gas concentration, distribution, soak time, and ventilation control; b. the anoxia and toxicity hazards associated with the gas; c. the possibility of damage from secondary thermal shock (cooling); d. conflicting requirements for venting during system discharge to prevent overpressurization versus sealing to prevent loss of agent; e. location and selection of the activating detectors; and f. the toxicity and corrosive characteristics of the thermal decomposition products of the agent. Where total-flooding gas extinguishing systems are used, area intake and exhaust ventilation dampers should be controlled, in accordance with appropriate standards, to maintain the necessary gas concentration (see NFPA 12, “Standard on Carbon Dioxide Extinguishing