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:
or turbulent diffusion in the direction. of flow, which may be important for short-duration releases. The case of a more general time-dependent release may be obtained by integrating Equation (9) with respect to time: o XWl) A - utt - T ]2 C .(4WK)I/A(t -. ),1/2. exp f 4Kix it . T) At [+2 i exp n-rK t cos n Yscos nnr* d- (10) where the release rate is Wf(T) curies/sec. In general, Equation (10) must be solved by numerical quadrature.. Near the source, convergence of the Fourier series terms In Equations (9) and (10) may be extremely slow. However, in this region, the effects of the far shore are not usually impor tant, and the series solution may be replaced by a single image source at the near shore (see the transient lake solution, Equations (19) and (20), Section 3.a.(2)(b) of this appendix). In this case, the solutions do not involve infinite series and present no convergence problems. b. Model Applications (1) Steady-State Stream Tube Model Application of the model requires determination of stream channel geometry, the cross stream distribution of flow, and the diffusion factor at representative river cross-sections downstream of the effluent discharge. In addition, definition of stream discharge is necessary (see Section 6 of this appendix). The preferred method of determining the flow cross-sectional distribution is by current-meter measurements using standard stream-gaging techniques. Because it is not always practical to obtain velocity measurements at every river cross-section at which concentration distributions are desired, transverse velocity distributions may be estimated from observed stream bottom profiles and the application of steady-state flow equations such as Manning's formula to channels of compound cross-section (Refs. 17 and 18). Evalatio ofthe iffuionfactrKu--d requires a separate determination of the dif Evaluation of the diffusion factor ;;I fusion coefficient.Ky. For steady open-channel flow, Ky can be determined from hydrodynamic