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:
ined by integration of Equation (7) over the source dimensions. If the source is located in the river between distances ysl and y.2 (cumulative discharges qsl and qs2), the area source solution may be obtained from Equation (7) by integration with respect to qs between the limits qsl < qs Iq s2. XAreaj)-W L+ n2w2Dx e" QT n.1 sin na cos n (qs 2 +qsl "niq no Q cos where 7 Q Note that the more familiar solutions for the concentration, as a function of x and y in a uniform, straight, rectangular channel of constant velocity U, can be obtained immediately from Equations (7) and (8) through the transformation of the terms within the brackets: {D/Q2} {K yUB2} The more general forms given by Equations (7) and (8), however, are preferable, since they are applicable to irregularly shaped channels. Yotsukura and Sayre (Ref. 16) have recently gen eralized Equations (5) and (6) so that these can be applied to any nonuniform channel with a minor modification to the diffusion factor. (2) Transient Release Model In many cases, routine releases of radioactive effluents are batched and infrequent, rather than continuous. In such cases, it may be important to calculate concentrations as a function of both time and space. The concentration in a straight, rectangular channel cor responding to the instantaneous release of a finite quantity of material from a vertical line source at x = 0 and y - ys is: C " - ePxp -x -- _t) + 2 Jlexp .cos n Y- cosnirfJ(9) (4WKxt) 112A BF 1.113-7 (7) (8) where A is the cross-sectional area; B is the channel width; i is the longitudinal turbulent transport coefficient (vertically averaged, two M is the amount of activity released (in curies); t is the time after the release; 'and the other terms are as previously defined. Note that this solution accounts for 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