PAVAN: An Atmospheric-Dispersion Program for Evaluating Design-Basis Accidental Releases of Radioactive Materials from Nuclear Power Stations (NUREG/CR-2858)

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Publication Information

Manuscript Completed: September 1982
Data Published: November 1982

Prepared by:
T. J. Bander

Pacific Northwest Laboratory
Richland, WA 99352


Prepared for:
Division of Systems integration
Office of Nuclear Reactor Regulation
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555

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This report provides a user's guide for the NRC computer program, PAVAN, which is a program used by the U.S. Nuclear Regulatory Commission to estimate downwind ground-level air concentrations for potential accidental releases of radioactive material from nuclear facilities. Such an assessment is required by 10 CFR Part 100 and 10 CFR Part 50. The program implements the guidance provided in Regulatory Guide 1.145, "Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants."

Using joint frequency distributions of wind direction and wind speed by atmospheric stability, the program provides relative air concentration (X/Q) values as functions of direction for various time periods at the exclusion area boundary (EAB) and the outer boundary of the low population zone (LPZ). Calculations of X/Q values can be made for assumed ground-level releases (e.g., through building penetrations and vents) or elevated releases from free-standing stacks.

Various options may be selected by the user. They can account for variation in the location of release points, additional plume dispersion due to building wakes, plume meander under low wind speed conditions, and adjustments to consider non-straight trajectories. It computes an effective plume height using the physical release height which can be reduced by inputted terrain features. It cannot handle multiple emission sources.

A description of the main program and all subroutines is provided. Also included as appendices are a complete listing of the program and two test cases with the required data inputs and the resulting program outputs.

Page Last Reviewed/Updated Wednesday, March 24, 2021