Document: NRC Regulatory Guide
Document ID: e5306f4f-dc8c-4f60-a71c-af7ad4080384
Document Type: regulatory_guide
Title: Aquatic Environmental Studies for Nuclear Power Stations + HISTORY - HISTORY 12/2014 – DG-4023 -Proposed New Guide
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1318/ML13186A085.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.24
CFR Part: 
CFR Title: 

Content:
fect aquatic habitats and species in several ways. The distribution, abundance, and richness of species in or near the discharge area should be described, including identification of important habitat requirements (see above section, Identification of Important Species and Habitats). Physical alteration of habitat occurs through scouring and/or other sediment transportation processes as well as removal or relocation of certain substrate components and of SAV that occur in the receiving water body. Although such alterations may be difficult to estimate quantitatively, qualitative analyses should be included when quantitative predictions are not possible. Analysts should evaluate thermal pollution (e.g., heat shock and cold shock) in the context of species’ thermal tolerance ranges and lethal temperature thresholds. Aquatic ecological analysts should work closely with hydrologists to determine the locations and physical properties of the dynamic thermal plume. Analysts should model and map the three-dimensional thermal plume under various discharge scenarios and throughout different seasons and water availability scenarios (e.g., droughts) paying particular attention to thermal tolerances of resident species in the immediate area as well as migratory species for which the thermal plume could be a barrier to upstream or downstream movement. Other potential effects that could occur because of the discharge include discharge of contaminants (sometimes including radionuclides), gas supersaturation, low dissolved oxygen concentrations, and stimulation of thermophilic nuisance organisms. Effects need to be quantitatively analyzed when practical (otherwise, qualitative analysis is acceptable) to determine impacts on habitat area, habitat quality, species distribution, prey availability, and population size, trends, and stability. Cooling Tower Drift Analyses Operation of cooling towers releases plumes of water vapor and droplets of condensed water to the atmosphere. The