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:
for Decisionmaking; and o 40 CFR Parts 125; “Criteria and Standards for the National Pollutant Discharge Elimination System.” 2.3.5.3 Related Guidance • NUREG-1555, “Standard Review Plans for Environmental Reviews for Nuclear Power Plants: Environmental Standard Review Plan”, Section 2.4; and • RG 4.2, “Preparation of Environmental Reports for Nuclear Power Stations;” 2.3.5.4 Considerations, Regulatory Experience, and Staff Position Cooling water intake and discharge system features, such as canals and thermal plumes, can attract and entrap organisms, principally fish. This can increase the concentration of important fish species near the station site, leading to higher mortalities from station-related causes such as impingement, cold shock, or gas bubble disease. Entrapment can also interrupt normal migratory patterns. Site evaluation should consider the design and placement of cooling system features and the risk that the cooling system will hold fish in an area for longer than the normal period of migration or will entrap them in areas where direct or indirect factors, such as limited food supply or unfavorable temperatures, may adversely affect them. The unnatural warmth of canals or areas where cooling waters are discharged may induce fish to remain there; if the station ceases to operate during the winter, the abrupt drop in water temperature may be lethal to these fish. Site characteristics should therefore accommodate design features that mitigate or prevent entrapment. Sites requiring the construction of intake or discharge canals should be avoided unless it would be possible to prevent or limit the entry of important species into the canal through screening. Section 316(a) of the CWA required EPA to issue regulations regarding point sources with thermal plumes, while section 316(b) required regulations for the design and operation of intake structures. State programs that specify maximum impacts allowed on source water volume and discharge