1. NAME AND TITLE

RAID: Monte Carlo Multibend Duct Shielding Code.

RAID is a translation and extensive modification of the CCC-9/L-05 code package, now obsolete.

2. CONTRIBUTORS

USAF Nuclear Aerospace Research Facility (NARF), General Dynamics, Fort Worth, Texas.

Air Force Weapons Laboratory, Kirtland Air Force Base, New Mexico.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 7090 and 7094.

4. NATURE OF PROBLEM SOLVED

RAID evaluates the energy, angular distribution, and intensity of either the scattered neutron or gamma-ray flux that penetrates a straight cylindrical or a multibend duct. A neutron or gamma-ray source may be described with a set of from 1 to 30 point sources. The energy and angular distribution and the intensity of the scattered flux are calculated for each of a set of from 1 to 30 detector points.

The code has been used in the analysis of the gamma-ray radiation environment above a fallout field, where the effect of the air-ground interface is taken into account.

The geometry routine is sufficiently flexible for the description of many of the shield configurations encountered in reactor, weapons, and space shielding.

5. METHOD OF SOLUTION

The Monte Carlo method represents a Neumann series solution of the integral transport equation. Included in the sampling techniques are splitting, Russian Roulette, statistical estimation, and a method of importance sampling in the source angular distributions.

The code provides for the calculation of the energy and angular distribution of the scattered neutron or gamma-ray flux, the total scattered neutron or gamma-ray flux and dose rates, and the unscattered neutron or gamma-ray flux and dose rate.

A library of cross sections which can be easily changed is packaged with the code.

6. RESTRICTIONS OR LIMITATIONS

There are no known restrictions implied by storage allocation or argument range due to approximations.

7. TYPICAL RUNNING TIME

No study of typical running time has been made by RSIC. Estimated running time for the two packaged sample problems on the IBM 7090: 0.11 hour.

8. COMPUTER HARDWARE REQUIREMENTS

The code was designed to run on the 32 K IBM 7090 and 7094, and on the CDC 6600 computers. 12 tape units are used on the IBM 7090.

9. COMPUTER SOFTWARE REQUIREMENTS

The code has been compiled and problems executed on the IBM FORTRAN IV IBJOB Monitor in the IBSYS Operating System. Standard I-O, overlay and systems, and 8 additional tape assignments were made. It was designed to be compatible with FORTRAN IV for the CDC 6600 computer.

10. REFERENCE

J. A. Moore, J. B. Eggen, and F. O. Leopard, "Monte Carlo Procedure for Analysis of Radiation in Ducts (RAID)," AFWL-TR-67-9 (August 1967).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code, a cross section data library, and input and output for two sample problems.

12. DATE OF ABSTRACT

January 1968; updated July 1981.