RSIC CODE PACKAGE CCC-445
  
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. 

KEYWORDS: GAUSSIAN PLUME MODEL; TRAJECTORY