Document: NRC Regulatory Guide
Document ID: 239cc7c1-f2cb-46cc-945d-8009db28aa6c
Document Type: regulatory_guide
Title: General Site Suitability Criteria for Nuclear Power Stations + HISTORY - HISTORY 12/2023 – DG-4034 , Proposed Revision 4 12/2011 – DG-4021 , Proposed Revision 3 02/1995 – DG-4004, Second Proposed Revision 2 11/1992 – DG-4003, Proposed Revision 2 (Rev. 4)
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML2312/ML23123A090.pdf
Revision Date: 2023-10
Chapter: 
Section ID: RG-4.7
CFR Part: 
CFR Title: 

Content:
dependable system of water sources is available under postulated occurrences of natural phenomena and site-related accidental phenomena, or combinations of such phenomena, as discussed in RG 1.59. RG 1.27 provides guidance on water supply for the ultimate heat sink and discusses the related safety requirements. NUREG-0800, Section 2.4.1, “Hydrologic Description,” notes that the applicant should identify the sources of hydrometeorological, and stream flow data used to determine that an adequate water supply exists for safety-related SSCs. NUREG-0800, Section 2.4.4, “Potential Dam Failures,” describes NRC staff review procedures related to potential loss of water supply due to dam failures and the effects of this loss on safety-related SSCs. For a site to be suitable, there should be reasonable assurance that the applicant can obtain, from the appropriate State, local, or regional agency, permits for water use and for water consumption in the DG-4034, Page 25 quantities needed for a commercial nuclear power plant of the stated approximate capacity and type of cooling system. For both safety and environmental reasons, when identifying potential sites on rivers, small shallow lakes, or coastlines, it is important to consider whether essential water will be available and flow requirements can be met during periods of low flow or low water level. Both the frequency and duration of periods of low flow or low water level should be determined from the historical record and, if the cooling water is to be drawn from impoundments, for projected operating practices. If stream flow records do not cover a period sufficiently long to encompass major droughts or the probable minimum flow for the region, statistical techniques or numerical models may be used to extend and complement the period of record in order to identify the expected minimum flow for the region. The U.S. Geological Survey 7Q10 calculation is an accepted screening-level method for estimating potential