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:
Plan;” • RG 4.2, “Preparation of Environmental Reports for Nuclear Power Stations;” and • RG 4.11, “Terrestrial Environmental Studies for Nuclear Power Stations.” 2.3.3.4 Considerations, Regulatory Experience, and Staff Position Generally, the most critical migratory routes relevant to commercial nuclear power station siting are those of aquatic species in water bodies associated with cooling systems. In assessing potential impacts on aquatic migratory species, five site conditions should be identified and evaluated: (1) narrow zones of passage, (2) migration periods that coincide with maximum ambient temperatures, (3) the potential for major modification of currents by station structures, (4) the potential for increased turbidity during construction, and (5) the potential for entrapment, entrainment, or impingement by or in the cooling water system and for blocking of migration by facility structures or effluents. Seasonal or daily migrations are essential to the reproductive capacity of some important species. Disruption of migratory patterns can result from partial or complete blockage of migratory routes by structures, discharge plumes, environmental alterations, or human activities (e.g., transportation or transmission corridor clearing and site preparation). Narrow zones of passage for migratory animals in some rivers and estuaries may be restricted or blocked by station operation. Partial or complete blockage of a zone of passage may result from the discharge of heat or chemicals to receiving water bodies or from the construction and placement of power station structures in the water body. Strong-swimming aquatic animals often avoid waters of adverse quality, but larval and immature forms are usually moved and dispersed by water currents. It is therefore DG-4034, Page 40 important in site selection to consider potential effects on the routes and times of movement of immature individuals. Some species migrate in central, deeper areas, while