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:
nt structure within that portion of the water body likely to be affected by the discharge should be discussed relative to its impact on model applicability. 4. Dichargf Receiving Water Interactions a. Jet Entrainment. The MAT should indicate whether jet mixing is the dorninant thermal dispersion mechanism in the near-field. The principal criterion for jet entrainment is the initial densimetric Froude number, the extreme operating range of which should be specified in the table. Model entries should cite the densimetric Froude number limits of applicability for each model. A number of models utilize empirical entminment coeftfcets to simulate jet mixing. In such cues, the numerical value(s) of coefficients applicable to prototype conditions should be given for each orthogonal direction in which entrainment is modeled, and the text should contain the rationale for selection of each coefficient. b. Cross Flow. In the presence of an ambient current, all discharges, regardless of initial flow direction, ultimately flow in the ambient current direction. If the current interacts in the near-field with a noncoincidental discharge, cross flow conditions prevail, and the MAT should reflect this fact. The principal criterion for cross flow is the velocity ratio defined as the ratio of initial discharge velocity to ambient current velocity. The MAT should contain the operating range of velocity ratios for the prototype and the range of applicability for each model. If the initial velocity ratio is sufficiently small, presure drag effects on the discharge by the ambient current can be significant. In order to simulate the pressure force exerted on the discharge, many models employ an empirical relation containing a drag coeficient. When such is the case, the coefficient should be specified as a MAT entry, and the functional form of the relation should be presented in the text. c. Natuba Turbulence. Natural water bodies possess a varying degree of natural turbulence.