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:
in inflow 5. Half-life of constituent The model is initialized with concentration C(o) at time t 0 0. The first period, (O<t<t,), corresponds to stratified conditions. Concentration in the epilimnion during this period is CE =a - ra --b C(o)]e-bt (48) Cliqi qt a b T- + E E where Ct is the input concentration in the upper layer; qt is the inflow to the upper layer; VE is the volume of epilimnion; and X is the decay constant and is - ln2/t½. 1.113-34 k" " -I-°•/•R-Lb 0.1 q5 - w CO qb >_ R-"1/4. 0.0 Pfu' Ro, 0.1 R~~ no*,0 0.oo1 I JL I 1 1 Rill I I I l l I 1 I1l l 0.001 0.01 011 HALI=-LIFt•/FLUSHINO TIME r FIG' URE 12. CONCENTRATION IN-PART"IAL.LY MIXED CASE \K \ a. Stratified VolVlumel VE Conncentration CE Volume VH Concentration CH CE ¶qlC SCH b. Unstratified Volume (E + V0 Concentration CM FIGURE 13. LUMPED PARAMETER STRATIFIED RESERVOIR MODEL 1.113-36 Ci Cif C, q i *" CM The concentration in the lower layer during this period is .i/C H a , - [a ' - b 'C (o ) ]e .- b 't H (49) V ' Ct'qt' VH where C,' is the input concentration to the lower layer; qi' is the inflow to the lower layer; and VH is the volume of hypolimnion. During turnover, instantaneous mixing of the two layers is assumed as CEVE + CHVH C~r ,,E'+ H (50) During the unstratified flow period, (tl<t4t2), the concentration is a " ' ( a " -b " C T ) e -b " ( t 1:)- t l ) b" (51) all " C t "q t I " a q t"1 "" T-•----- b'"* T• +.A T VT where C," is the input concentration for the total pond; qi" is the inflow; and VT is the total volume. Subsequent seasonal stratification cycles repeat with Equation (48), but with the latest fully mixed concentration substituted for C(o). Simple methods such as the well mixed, partially mixed, and stratified models covered in this and the previous section are most suitable for estimating concentrations in reservoirs, ponds, and lakes that are downstream of the radionuclide discharge and consequently already par tially mixed. In such a case, the hydraulics of the