**1. NAME AND TITLE**

G33-GP: Kernel Integration Code System -- Multigroup Gamma-Ray Scattering Using the GP Buildup Factor.

The present version is based on CCC-075/G3 contributed by Los Alamos National Laboratory, Los Alamos, N.M. and modified by JAERI. The code was modified in October 1988 to accommodate the ANS-6.4.3 1988 buildup factor compilation (26 materials).

The G-P buildup factor coefficients for the elements molybdenum to uranium were updated in July 1990 from new PALLAS calculations based on DLC-136/PHOTX. The DLC-129/ ANS643 package was also updated with data from the PALLAS calculations.

The code was modified in February 1994 to allow input of multiple problems, increase the scatter grid divisions, and use list-directed input.

**2. CONTRIBUTORS**

Japan Atomic Energy Research Institute, Tokai-mura, Japan.

Nippon Atomic Industry Group Co., Ltd., Japan.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; IBM PC (C00494IBMPC01).

**4. NATURE OF PROBLEM SOLVED**

G33-GP estimates gamma-ray scattering from a point source to a series of point detectors. The output includes detector response due to each source energy, as well as a grouping by scattered energy in addition to a simple, uncollided result. Although G33 is basically a single-scatter calculation, it also includes a correction for multiple scattering by applying a buildup factor for the path segment between the point of scatter and the detector point. Results are recorded with and without buildup. Surfaces, defined by quadratic equations are used to provide a three-dimensional description of the physical geometry. It evaluates scattering effects in those situations where more exact techniques are not economical.

**5. METHOD OF SOLUTION**

An orthogonal scattering geometry is superimposed on the original QAD geometry; the midpoint of the orthogonal cube is ascertained; the QAD region in which this point is located is determined; and the entire scatter volume is assumed to be of the ascertained QAD material and concentrated at the midpoint. G33 traces a ray from the source point to each scatter point, calculates uncollided photon flux at that point, and determines the contribution from each scatter point to the detector. The library of photon cross sections and buildup factor coefficients are read from data files. The buildup factor is computed from the coefficients using the Geometric Progression (GP) fitting function.

**6. RESTRICTIONS OR LIMITATIONS**

The following limits apply: 50 x 50 x 50 scatter grid, 50 QAD boundaries and regions, and 30 energy groups.

**
7. TYPICAL RUNNING TIME**

The two sample problems required 4.0 and 4.9 minutes on a 25 MHz personal computer 386 with a math coprocessor.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code runs on the IBM PC. An 8087 co-processor and hard disk are required. The only compiler dependencies are in OPEN statements and the TIMER routine.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The IBM PC version was compiled by the Microsoft compiler (Version 5.1) and runs under MS DOS.

**10. REFERENCES**

**a. Included in the documentation:**

D. K. Trubey, Informal Notes, ORNL (February 1994).

Richard E. Malenfant, "G3: A General Purpose Gamma-Ray Scattering Code," LA-5176 (1973).

**b. Background information:**

Y. Harima, Y. Sakamoto, S. Tanaka, and M. Kawai, "Validity of the Geometrical
Progression Formula in Approximating Gamma-Ray Buildup Factors," *Nucl. Sci. Eng.* 94,
24-35 (Sept. 1986).

D. K. Trubey, "New Gamma-Ray Buildup Factor Data for Point Kernel Calculations: ANS-6.4.3 Standard Reference Data," NUREG/CR 4740 (ORNL/RSIC-49/R1), Oak Ridge National Laboratory (August 1991).

"Gamma-Ray Attenuation Coefficients and Buildup Factors for Engineering Materials," an American National Standard, ANSI/ANS-6.4.3-1991 (August 26, 1991). Note that the data are the same in ORNL/RSIC-49/R1 and the ANS-6.4.3 Standard.

Y. Sakamoto and S. Tanaka, "QAD-CGGP2 and G33-GP2: Revised Versions of QAD-CGGP and G33-GP Codes with Conversion Factors from Exposure to Ambient and Maximum Dose Equivalents," JAERI-M 90-110, Japan Atomic Energy Research Institute (June 1990).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one DS/HD 5.25-in. (1.2 MB) diskette in DOS format which contains the source code, executable, data files, and sample problem input and output.

**12. DATE OF ABSTRACT**

May 1986; October 1988; July 1990; October 1991, June 1993, April 1994.

**KEYWORDS:** GAMMA-RAY; KERNEL; COMPLEX GEOMETRY;
MICROCOMPUTER