TH35  Atmospheric Transport and Dispersion Modeling for Severe Accident Consequence Analysis

Atmospheric transport of radioactive material is an important component to estimating the consequences of severe accidents. This session discusses current and planned atmospheric transport modeling capabilities of the MACCS computer code, which is the sole U.S. code for probabilistic consequence analysis. MACCS is used widely within the U.S. by NRC, DOE, nuclear power plant licensees and applicants, academia, and research organizations and is also used internationally. This session also discusses a benchmarking study of the MACCS code’s Gaussian plume segment model against the newly integrated HYSPLIT particle tracking model and potential updates to address near-field dispersion in support of emergency planning zone size determinations for small sites.

The session also discusses research in France for addressing uncertainty in atmospheric dispersion simulations of nuclear emergencies and the recent results of the Organisation for Economic Co-operation and Development / Nuclear Energy Agency (OECD/NEA) Benchmark Study of the Fukushima Accident Phase II analyses on the release of radioactive material into the environment.

  • Jonathan Barr, Acting Branch Chief, Division of Systems Analysis, RES/NRC tel: 301-415-1089, e-mail:


  • AJ Nosek, Reactor Systems Engineer, Division of Systems Analysis,, RES/NRC e-mail:

Page Last Reviewed/Updated Monday, August 26, 2019