Document: NRC Regulatory Guide
Document ID: 4d46a966-d280-43da-9b03-8b0abe7b29ce
Document Type: regulatory_guide
Title: Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2120/ML21204A065.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.183
CFR Part: 
CFR Title: 

Content:
0.015 10+ 0.0 1.0 0.7 0.012 A-5.6.2 Re-Evaluated AEB 98-03 with multi-group method: Aerosol deposition removal coefficients for the main steamline piping between the MSIVs and downstream of the MSIVs may apply an updated AEB 98-03’s (Ref. A-17) use of the Stokes settling velocity physics parameters with the multi-group method which will be evaluated on an individual case-by-case basis. The method below computes both total effective aerosol removal efficiencies (TEAREs) (i.e., filter efficiencies) and equivalent removal coefficients, λ, (hr-1). When evaluating the Stokes settling velocity, utilize the aerodynamic mass median diameter (AMMD), ݀௔, based on a distribution directly measured from experiments to evaluate the settling velocity where the specific aerosol parameter distributions of shape factor, density, volume equivalent diameter do not need to be defined. Therefore, the Stokes settling velocity can be re-written in terms of the aerodynamic diameter, ݀௔ as: 4 The credit described in this regulatory position will supersede the aerosol settling estimates previously provided in the NRC staff document AEB 98-03, “Assessment of Radiological Consequences for the Perry Pilot Plant Application Using the Revised (NUREG-1465) Source Term,” dated December 9, 1998 (Ref. A-16), when Revision 1 of RG 1.183 is used. DG-1389, Appendix A, Page A-10 ݑ௦= ఘబ⋅ ௗೌమ ⋅ ௚ ⋅ ஼ೞ(ௗೌ) ଵ଼ఓ , Equation A-1 where: ߩ଴ = aerosol unit density = 1.0 g/cm3 ݀௔ = aerosol aerodynamic diameter ݃ = gravitational acceleration ܥ௦(݀௔) = Cunningham slip factor as a function of ݀௔ ߤ = viscosity The State-of-the-Art Report [SOAR] on Nuclear Aerosols (Ref. A-17) provides a summary of experimental observations from integral experiments involving irradiated fuel to infer characteristics of aerosols under light-water reactor severe accident conditions. The SOAR recommends a log-normal distribution for aerosols in the reactor coolant system (AMMD