Document: NRC Regulatory Guide
Document ID: c9ebcbb0-96c4-4d29-be51-5acae9cc858a
Document Type: regulatory_guide
Title: Estimating Aquatic Dispersion of Effluents from Accidental and Routine Reactor Releases for the Purpose of Implementing Appendix I (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740390.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.113
CFR Part: 
CFR Title: 

Content:
by the International Commission on Radiological Units and Measurements (ICRUM). 1.113-1 the modeling techniques discussed represent adaptations of work currently available in the liter ature. Because. of increasing environmental concerns during the past decade, considerable effort has been expended in advancing the state of the art of water quality simulation and thermal plume modeling. The models discussed herein draw heavily from this body of information. Although specific models are considered, they are intended to represent specific classes of models. Furthermore, discussions of particular techniques for determining model parameters are intended to provide guidance and to stress the desirability of determining these parameters from physical principles or measurements. Applicants may, however, use modeling techniques other *1 than those considered herein. In particular, physical hydraulic models that may have been con structed for hydrothermal studies or other purposes may often be used as reliable predictive tools for radionuclide dispersion. Tracer release studies conducted in situ can provide accurate predictions without need for a model. The degree of realism inherent in each model described in this guide depends on the ability of that model to account for the physical processes involved and the validity of model coeffi cients and assumed future flow fields. As a general rule, more complex models are capable of yielding more realistic results. However, a realistic model requires realistic input data, and little is gained by using highly sophisticated calculational models when the input parameters are ill-defined. The simplest models are closed-form analytical solutions of the governing transport equations. Such solutions are possible only for simplified cases. It is seldom pos sible to obtain analytical solutions for time-dependent flow fields or for complex receiving water geometry. Consequently, any analytical solution should be carefully assessed by the