1. NAME AND TITLE

QBSHIELD: Spherical Shield Design for Gamma-Ray Sources Using the Buildup Factor Method.

2. CONTRIBUTOR

University of Pittsburgh, Pittsburgh, Pennsylvania.

3. CODING LANGUAGE AND COMPUTER

Microsoft QuickBASIC 4.5 or MS-DOS 5.0 QBasic; IBM PC and PS/2.

4. NATURE OF PROBLEM SOLVED

Quick spherical shielding design for storage of radionuclide sources in research settings is done based on photon energies, abundances, activity, desired exposure rate at a specified point, choice of shielding material, source radius, and assumed density of shielding material. Shield thickness and weight are computed, along with exposure rates.

5. METHOD OF SOLUTION

The program is interactive and accepts ASCII file input or keyboard input. Files MU.DAT and BUILDUP.DAT are supplied and must be in same directory as QBSHIELD. The highest energy photon should appear first in the input. For each photon abundance and energy (0.5 MeV .le. E .le. 10 MeV), the program looks up a linear attenuation coefficient, and calculates a mass attenuation coefficient and looks up a specific exposure rate constant. For the highest energy photon, QBSHIELD iteratively searches for a shield thickness that satisfies the exposure criterion (that is, a specified exposure rate at surface of shield, at a specified distance from center of shield, or at a specified distance from shield surface). Since only one photon energy is used for the first pass, the user may enter alternative shield thicknesses until the total exposure rate is as desired. The user can also specify different geometries or shield densities, if desired.

6. RESTRICTIONS AND LIMITATIONS

Gamma-ray energy range is limited to 0.5 to 10 MeV for water, ordinary concrete, iron, lead and uranium.

7. TYPICAL RUNNING TIME

QBSHIELD is interactive; it typically takes less than one minute.

8. COMPUTER HARDWARE REQUIREMENTS

The code is known to run on IBM PCs and compatibles and the IBM PS/2 Models 50, 60, and 70.

9. COMPUTER SOFTWARE REQUIREMENTS

The source code is in Microsoft QuickBASIC 4.5, which will also run under MS-DOS 5.0 QBasic. The executable version requires no additional software.

10. REFERENCES

Daniel J. Strom, ``QBSHIELD.BAS,'' Informal Notes from University of Pittsburgh (Sept. 24, 1991).

Anthony Foderaro, ``The Photon Shielding Manual,'' The Pennsylvania State University Informal Report, Second Edition (April 1978).

11. CONTENTS OF CODE PACKAGE

Included is one DS/HD (1.2 MB) 3.5 inch or 5.25 inch diskette containing source code, executable code, MU.DAT, BUILDUP.DAT, sample input and output files.

12. DATE OF ABSTRACT

December 1991.