Document: NRC Regulatory Guide
Document ID: f4c5fb1d-efb9-4168-9804-5ad3f6f64d06
Document Type: regulatory_guide
Title: Reporting Procedure for Mathematical Models Selected To Predict Heated Effluent Dispersion in Natural Water Bodies
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML0037/ML003739535.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.4
CFR Part: 
CFR Title: 

Content:
___ FIELD , ' LONGITUDINAL •, " DIMENSION LATERAL _ _ __ uj 0 1 VERTICAL ,' " MATHEMATICAL APPROACH f . PROXIMATIONS ,• .•' MODEL VERIFICATION ' COMPUTER PROGRAM _ _ ___ EXHIBIT 1 4.4-5 APPENDIX A BEHAVIOR OF THERMAL DISCHARGES 1. Nomenclature From a phenomenological viewpoint, a thermal discharge can be partitioned into three spatial fields, ; ch characterized by a different set of dominant pocesses. The "near-field" is marked by the interaction between the kinematic heated effluent and the receiving water body. Since the effluent velocity usually exceeds the receiving water velocity, the discharge is referred to as a "jet." By definition, jet momentumn forces predominate in the near-field, however, buoyancy forces may also be important. In the "far-field," ambient flow determines the shape and position of the thermal discharge, which typically is called a "plume." The 11-defined region joining near- and far-fields has been designated variously is the "interamelate-field" or transition zone. In this region the heated discarg changes from an active jet to a peshie plume as the effluent comes increasingly under the Influenc of the receiving water body. In the tmanition region both the discharge flow and the ambient flow ame important. This overview of discharp/lreceiving water interactions serves to introduce the fundamental terminology of thermal dischrg analysis, as well as to identify the grows behavior of heated effluents. L. Engqneering Deailn Fact-ors Governing Therma Disp rsion Outfall designs for aqueous thermal effluent from power plants have changed drastically in recent years. Early structures usually consisted of simple shoreline canals or pipes that discharged their contents at or just below the water surface. Heated releases fromn structures of this type tend to produce thin surface plumes of large areal extent, which are efficient in transferring heat to the stniosphre. Currently, many discharge structures are being designed to maximize dilution