1. NAME AND TITLE

PFPL: Puff-Plume Atmospheric Deposition Model

2. CONTRIBUTOR

Savannah River Laboratory, Aiken, South Carolina through the Energy Science & Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

DEC Vax 11/780; Fortran 77

4. NATURE OF PROBLEM SOLVED

PFPL is an interactive transport and diffusion program developed for real-time calculation of the location and concentration of toxic or radioactive materials during an accidental release. Deposition calculations are included. The potential exists at the Savannah River Plant for releases of either toxic gases or radionuclides. The automated system developed to provide real-time information on the trajectory and concentration of an accidental release consists of meteorological towers, a minicomputer, and a network of terminals called the Weather Information and Display (WIND) System. PFPL which simulates either instantaneous (puff) or continuous (plume) releases is the primary code used at Savannah River for emergency response. Data files are provided for demonstration. The software for archiving the required on-line meteorological data is not included. Subroutines used for graphic display of results and operational control of the DEC VT100 and Tektronix terminals in the terminal network are included. Anyone wishing t use these routines must make appropriate modifications to the file TERMINALS.DAT. The DAT files provided were copied during the afternoon of December 28, 1983. Test runs attempting to use these files should specify release times on or before that date. Any user wishing to obtain numerical output only form the model based on conditions in his locality must supply appropriate wind data for the program.

5. METHOD OF SOLUTION

In the PFPL model the diffusion process is separated into two phases. In phase I, the Gaussian cloud grows as a function of wind speed and stability class. Near the ground, the vertical concentration becomes logarithmic. Phase II begins when the vertical standard deviation reaches a value of 0.8H, where H is the depth of the atmosphere's turbulent layer. At the horizontal distance from the source where the standard deviation - 0.8H, the material remaining in the cloud is redistributed to a uniform vertical concentration throughout the mixed-layer. The logarithmic surface layer remains. The basic theory of the model assumes that the dry deposition rate is limited by surface deposition processes and by the rate at which turbulence can bring pollutants down to the surface (deposition) layer. The net effect of the two transfer rates determines the cloud depletion rate and surface concentrations. Depletion of the cloud by rain and radioactive decay is treated as an independent process. the fundamental equation solved is the general advection-diffusion equation, including gravitational settling, rainout, and radioactive decay.

6. RESTRICTIONS OR LIMITATIONS

Much of the software is specific to the Savannah River Plant Environment.

7. TYPICAL RUNNING TIME

The program is interactive.

8. COMPUTER HARDWARE REQUIREMENTS

PFPL runs on the DEC VAX 11/780.

9. COMPUTER SOFTWARE REQUIREMENTS

The system was developed on VMS 3.4 and is written in Fortran 77. VAX/VMS system services and Fortran extentions are proprietary Tektronix PLOT10 Interactive Graphics Library.

10. REFERENCES

A. J. Garrett, C. E. Murphy, Jr., "A Puff-Plume Atmospheric Deposition Model for Use at SRP in Emergency Response Situations," DP-1595 (May 1981).

11. CONTENTS OF CODE PACKAGE

Included are referenced document and 2 DS/HD (1.2MB) diskettes which contain the source, binary data files and sample interactive session.

12. DATE OF ABSTRACT

September 1992.