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:
hausted. b. The fire-water supply should be calculated on the basis of the largest expected flow rate for a period of 2 hours, but not less than 1,136,000 liters (L) (300,000 gallons (gal)). This flow rate should be based (conservatively) on 1,900 liters per minute (L/min) (500 gal/min) for manual hose streams, plus the largest design demand of any sprinkler or deluge system, as determined in accordance with NFPA 13, “Standard for the Installation of Sprinkler Systems” (Ref. 75), or NFPA 15, “Standard for Water Spray Fixed Systems for Fire Protection” (Ref. 76). c. If tanks are used for water supply, two 100-percent system capacity tanks (minimum of 1,136,000 L (300,000 gal) each) should be installed. They should be interconnected to allow pumps to take suction from either or both. However, a failure in one tank or its piping should not cause both tanks to drain. Water supply capacity should be capable of refilling either tank in 8 hours or less. d. Common water supply tanks are acceptable for fire and sanitary or service water storage. When they are used, however, minimum fire-water storage requirements should be dedicated by passive means (for example, use of a vertical standpipe for other water services). Administrative controls, including locks for tank outlet valves, are unacceptable as the only means to ensure minimum water volume. e. Freshwater lakes or ponds of sufficient size may qualify as the sole source of water for fire protection but require separate redundant suctions in one or more intake structures. These supplies should be separated, so that a failure of one supply will not result in a failure of the other supply. f. When a common water supply is permitted for fire protection and the ultimate heat sink, the following conditions should also be satisfied: (1) The additional fire protection water requirements are designed into the total storage capacity. (2) Failure of the fire protection system should not degrade the function of the ultimate