1. NAME AND TITLE

COMRADEX4: Evaluator of Potential Radiological Doses in the Near (< 10 km) Environment of Radioactive Release.

AUXILIARY ROUTINES

HAA3B: Aerosol Behavior Lognormal Model.

RIBD2: Radioisotope Buildup and Decay Code and Library.

HAA3B is available from the National Energy Software Center, Argonne National Laboratory, Argonne, Illinois. RIBD2 is available as CCC-137 from RSIC.

2. CONTRIBUTOR

Rockwell International, Atomics International Division, Canoga Park, California.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370.

4. NATURE OF PROBLEM SOLVED

COMRADEX4 was developed to evaluate potential radiological doses in the near (<10 km) environment of radioactive releases, especially postulated accident releases. Consequence-mitigating natural phenomena and engineered safety features, such as aerosol deposition inside and outside containment, meteorological dispersion, multiple containments, filtration, and shielding, may be calculated. Potential doses to body organs may be calculated from sources retained in containment, distributed in the atmosphere, and inhaled.

5. METHOD OF SOLUTION

The code must be supplied with an initial radioisotope inventory, leakage and cleanup rates for each level of containment, and dose rate factors for each isotope and organ. The containment inventory model contains up to four shells with leakage, aerosol cleanup, and filtration factors, as well as radioactive decay.

Inventory equations both inside and outside containment are solved using a numerical method for quasi-linear equations. The meteorological dispersion is calculated from an anisotropic Gaussian cloud using Briggs' values for dispersion coefficients. Gravitational settling and dry deposition may be included for each of three isotope classes. A virtual point source release is employed. The gravitation model applies settling to both actual and image sources. Dry deposition is accounted for by uniform source depletion. Alternately, meteorological dispersion may be calculated from input attenuation factors.

In both approaches, the weather conditions may be changed three times. Doses from retained sources are calculated from uniform spherical volume sources using input removal coefficient, buildup factor, and shielding factor at a single energy. The standard breathing rates for inhalation doses are built in. The external beta- and gamma-ray cloud doses are calculated from analytical formulas for semi-infinite clouds. For modeled meteorology, the external gamma-ray cloud dose may be calculated from the anisotropic Gaussian cloud. A numerical integration is used. Doses may be calculated separately for two groups of isotopes, such as fuel and fission products. Dose sources may be saved on auxiliary storage and used for subsequent dose-only calculations.

6. RESTRICTIONS OR LIMITATIONS

COMRADEX4 allows a maximum of:

150 entries per class in leakage and fallout rate tables

5 release times

20 detector locations

3 isotope classes

4 containment levels

500 isotopes

12 organ dose rate factors per isotope.

7. TYPICAL RUNNING TIME

Thirty seconds plus 2 seconds per anisotropic Gaussian cloud gamma-ray dose calculation per detector location per release time are required.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on the IBM 360/370 computers. 300 K bytes of memory are required. Two logical units are used as input and output (units 5 and 6), and two additional units may be needed. Use of several other units is optional.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV (H extended) compiler is required. The operating system under which the program is executed is OS/370 VS2 Release 1.7.

10. REFERENCE

J. M. Otter and D. K. Chung, "Description of the COMRADEX_IV Code," N707I130047 (September 26, 1977).

11. CONTENTS OF CODE PACKAGE

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

12. DATE OF ABSTRACT

January 1982.