**1. NAME AND TITLE**

GAMLEG-JR: Multigroup Cross-Section Generator for Photon Transport Calculations.

**2. CONTRIBUTORS**

Japan Atomic Energy Research Institute, Tokyo, Japan, through the OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; FACOM 230-60/75 (A), IBM 360, 3033 (B).

**4. NATURE OF PROBLEM SOLVED**

GAMLEG-JR generates ANISN-format multi-group photon cross sections and group averaged gamma-ray energy absorption coefficients for use in the Sn-type transport calculations.

**5. METHOD OF SOLUTION**

GAMLEG-JR is a modification of PSR-86/GAMLEG which reads cross section data in tabular form for the photoelectric effect, pair production and coherent scattering. GAMLEG-JR generates these cross section data by simple empirical formulae as a function of atomic number Z. GAMLEG calculated analytically the energy integral of an equation for the average transfer cross section. However, this integration method was found inadequate for obtaining Legendre moments higher than 6th order at low energy region below about 0.1 MeV. GAMLEG-JR calculates this integral by the numerical integration based on Simpson's rule for equally spaced mu.

**6. RESTRICTIONS OR LIMITATIONS**

GAMLEG-JR provides up to 50 energy groups and up to nine Legendre moments for each of an unlimited number of elements. Flux weighting data are limited to a maximum of 500 values.

**7. TYPICAL RUNNING TIME**

The sample problem required less than 14 seconds of CPU time on the IBM 3033 computer.

Running time required to generate the cross sections of 20 group structure and nine Legendre moments for an element is about 6 seconds CPU on the FACOM 230-60/75.

**8. COMPUTER HARDWARE REQUIREMENTS**

OECD NEA DB tested GAMLEG-JR on the IBM 360. RSIC's execution of the sample problem on the IBM 3033 computer required 336 K in the FORT step and 232 K in the GO step.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The sample problem was executed using the Fortran H extended enhanced (FORTQ) compiler under MVS.

**10. REFERENCE**

S. Miyasaka and K. Minami, "GAMLEG-JR: A Production Code of Multi-group Cross Sections and Energy Absorption Coefficients for Gamma-Ray," JAERI-M 6936 (1977).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

June 1982; revised March 1984.

**KEYWORDS: ** MULTIGROUP CROSS SECTION PROCESSING; KERMA; GAMMA-RAY
CROSS SECTION PROCESSING