United States Nuclear Regulatory Commission - Protecting People and the Environment

Comparison of Average Transport and Dispersion Among a Gaussian, a Two-Dimensional, and a Three-Dimensional Model (NUREG/CR-6853)

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Publication Information

Manuscript Completed: October 2004
Date Published: October 2004

Prepared by:
C.R. Molenkamp
Atmospheric Science Division
Lawrence Livermore National Laboratory
7000 East Avenue
Livermore, California 94550

N.E. Bixler, C.W. Morrow
Sandia National Laboratories
Albuquerque, NM 87185-0748

J.V. Ramsdell, Jr.
Pacific Northwest National Laboratory
Richland, WA 99352

J.A. Mitchell, NRC Project Manager

Prepared for:
Division of Systems Analysis and Regulatory Effectiveness
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code Y6785

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The simplifying atmospheric transport and dispersion assumption used by MACCS2, the Nuclear Regulatory Commission's code for predicting off-site consequences, is tested by comparison to ADAPT/LODI, a state-of-the-art, three-dimensional advection-dispersion code. Also included in the comparison is the Nuclear Regulatory Commission's code for rapid emergency response, RASCAL, and a newer related code with upgraded dispersion and deposition modules, RATCHET. Meteorological data for the test were provided by the Department of Energy's Atmospheric Radiation Measurement Program Southern Great Plains site in central Oklahoma and Kansas, a site with a unique and comprehensive set of mesoscale meteorological data. Each model was run in its normal manner to produce the annual average integrated exposure and deposition for a series of rings at 16.1, 32.2, 80.5, and 160.9 km (10, 20, 50, and 100 miles) from a hypothetical release, and the integrated exposure and deposition for arc-sectors at the same set of distances and the 16 compass directions. Nearly all the annual average ring exposures and depositions and the great majority of the arc-sector values for MACCS2, RASCAL, and RATCHET were within a factor of two of the corresponding ADAPT/LODI values.

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