CCC-0445 PAVAN.

1. NAME OR DESIGNATION OF PROGRAM:  PAVAN (Atmospheric Dispersion Code
System for Evaluating Accidental Radioactivity Releases from Nuclear Power Stations).

3. DESCRIPTION OF PROGRAM OR FUNCTION

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 onsider non-straight trajectories. It computes an effective plume height using the physical release height which can be reduced by inputted terrain features.

4. 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 evaluated 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.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  The code cannot handle multiple emission sources.

6. TYPICAL RUNNING TIME

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

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES:

- T.J. Bander:
  PAVAN - An Atmospheric Dispersion Program for Evaluating Design
  Basis Accidental Releases of Radioactive Materials from Nuclear
  Power Stations
  NUREG/CR-2858, PLN-4413 (November 1982).

11. MACHINE REQUIREMENTS

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

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

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.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

          Nuclear Regulatory Commission
          Washington, D.C.

test-case data   mag tapeJCL to execute PAVAN                       DATTP
source program   mag tapePAVAN Source (FORTRAN4) (9/12/85)          SRCTP
source program   mag tapeIDAY Subroutine (ASSEMBLER)                SRCTP
test-case data   mag tapePAVAN test case # 1 (Input on unit 5)      DATTP
test-case data   mag tapePAVAN test case # 2 (Input on unit 5)      DATTP
test-case output mag tapeTest case # 1 unit 6 Output                OUTTP
test-case output mag tapeTest case # 2 unit 6 Output                OUTTP
report                   NUREG/CR-2858, PLN-4413 (November 1982)    REPPT