1. NAME AND TITLE

PAVAN: Atmospheric Dispersion Code System for Evaluating Accidental Radioactivity Releases from Nuclear Power Stations.

2. CONTRIBUTOR

Nuclear Regulatory Commission, Washington, D. C.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 3033 and 3038.

4. NATURE OF PROBLEM SOLVED

PAVAN estimates down-wind ground-level air concentrations for potential accidental releases of radioactive material from nuclear facilities. Options 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.

5. METHOD OF SOLUTION

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 or elevated releases from free-standing stacks. The X/Q calculations are based on the theory that material released to the atmosphere will be normally distributed (Gaussian) about the plume centerline. A straight-line trajectory is assumed between the point of release and all distances for which X/Q values are calculated.

6. RESTRICTIONS OR LIMITATIONS

The code cannot handle multiple emission sources.

7. TYPICAL RUNNING TIME

Each test case in the package required less than 8 cpu seconds on the IBM 3033 computer.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on the IBM 3033 and the IBM 3038 computers.

9. COMPUTER SOFTWARE REQUIREMENTS

The sample problems were executed on the ORNL IBM 3033 computer running OS/VS2 using the Fortran H extended enhanced compiler. The code also runs on the IBM 3038 computer running OS/VS using the Fortran G compiler.

10. REFERENCE

T. J. Bander, "PAVAN: An Atmospheric Dispersion Program for Evaluating Design Basis Accidental Releases of Radioactive Materials from Nuclear Power Stations," NUREG/CR-2858 (November 1982).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code, sample problem input and output.

12. DATE OF ABSTRACT

July 1983.