1. NAME AND TITLE

QAD-BSA: Point-Kernel Shielding Code System.

2. CONTRIBUTOR

EG&G Idaho, Inc., Idaho Falls, Idaho.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; CDC CYBER 176.

4. NATURE OF PROBLEM SOLVED.

QAD-BSA is a three-dimensional, point-kernel shielding code system based upon the CCC-48/QAD series. It is designed to calculate photon dose rates and heating rates using exponential attenuation and infinite medium buildup factors. Calculational provisions include estimates of fast neutron penetration using data computed by the moments method. Included geometry routines can describe complicated source and shield geometries. An internal library contains data for many frequently used structural and shielding materials, enabling the code to solve most problems with only source strengths and problem geometry required as input. This code system adapts especially well to problems requiring multiple sources and sources with asymmetrical geometry. In addition to being edited separately, the total interaction rates from many sources may be edited at each detector point. Calculated photon interaction rates agree closely with those obtained using QAD-P5A.

5. METHOD OF SOLUTION

In the gamma-ray calculation, the point kernel method used involves representing the gamma-ray source by a number of point isotropic sources and computing the line-of-sight distance from each of these source points to the detector point. Calculational provisions include estimates of fast neutron penetration using moments method data. Photon problems are solved by calculating the uncollided flux (assuming exponential attenuation) and then multiplying the flux by the appropriate infinite-medium buildup factor. Included neutron removal cross sections for 17 materials and neutron moments data for three reference materials permit approximate solutions of short-range fission-neutron shielding problems. Versatile geometry routines enable accurate description of complicated sources and hardware.

6. RESTRICTIONS OR LIMITATIONS

The internal data library provides gamma-ray heating conversion factors for 18 materials (e.g., aluminum, iron, and uranium) and includes photon attenuation coefficients for only 40 materials. The user may, however, substitute different attenuation, photon heating, and neutron heating coefficients for hydrogen, beryllium, boron and/or carbon. As many as 140 boundaries and 107 regions may be used, depending on the types of boundaries and regions. As many as 15 boundaries may be used for a single region, and as many as 10 source spectra may be used for a single case.

7. TYPICAL RUNNING TIME

No study has been made by RSIC of typical running times for QAD-BSA.

8. COMPUTER HARDWARE REQUIREMENTS

QAD-BSA is operable on the CDC CYBER 176 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required. The code was run under the NOS BE monitor system.

10. REFERENCES

a. Included in documentation:

T. E. Young, "The QAD-BSA Point-Kernel Shielding Code," EGG-PHYS-5267 (December 1980).

b. Background information:

CCC-48/QAD documentation.

11. CONTENTS OF CODE PACKAGE

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the source program and two sample problems.

12. DATE OF ABSTRACT

March 1982.

KEYWORDS: GAMMA-RAY; NEUTRON; KERNEL; COMPLEX GEOMETRY