Document: NRC Regulatory Guide
Document ID: fa5814c8-b91a-435c-8ee0-5cd4915f8b80
Document Type: regulatory_guide
Title: Performance-Based Emergency Preparedness for Small Modular Reactors, Non-Light-Water Reactors, and Non-Power Production or Utilization Facilities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1808/ML18082A044.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.242
CFR Part: 
CFR Title: 

Content:
atmosphere, release durations, release locations, physical/chemical form, and plume buoyancy. A-3.2 Meteorological Input An analysis to develop meteorological data may be needed to evaluate a range of meteorological conditions in a probabilistic fashion. Alternately, conservative transport and dispersion conditions may be assumed, although the conservatism of the selected conditions should be evaluated to ensure that the combination of parameters selected for transport and dispersion modeling was in fact conservative. The data needs of the selected atmospheric transport model (see Section A-3.3) should be considered in the selection of meteorological data. Selection of a source of meteorological data would include evaluation of data such as wind speeds, atmospheric stability, precipitation, mixing height, etc., for temporal and geographical representativeness. The quality and completeness of the meteorological data should be assessed. It should be noted that meteorological data is site specific. However, some applications could involve assessments that are not site specific. An explanation of the appropriateness of the meteorological data used for such assessments would be needed to evaluate the analysis. A-3.3 Atmospheric Transport Modeling An atmospheric transport model appropriate for the range of distances under consideration should be identified. In NUREG-0396, Gaussian-type models were used for atmospheric transport. For these types of models, dispersion parameters appropriate to the characteristics of the area and distance ranges under consideration should be identified, and conceptual approaches for the treatment of near-field effects such as elevated releases, building wake effects, plume meander, plume rise, etc. should also be identified. The selection of an atmospheric transport model should also involve selection of a conceptual approach for treatment of wet and dry deposition. Any DG-1350, Appendix A, Page A-3 assumptions made in the atmospheric