1. NAME AND TITLE

HEXAB-3D: Three-Dimensional Few-Group Coarse Mesh Diffusion Code for Neutron Physics Calculation of Reactor Core in Hexagonal Geometry.

2. CONTRIBUTOR

Institute for Nuclear Research and Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV(G) and Assembler; IBM 370 and IBM 3031.

4. NATURE OF PROBLEM SOLVED

HEXAB-3D solves the three-dimensional few-group diffusion model for the calculation of the basic neutron physical characteristics of power reactors in hexagonal geometry.

5. METHOD OF SOLUTION

The nine-point mesh-centered finite difference approximation of the neutron diffusion equation is used. The standard inner-outer iteration strategy is employed. Inner iterations are solved using two different incomplete factorization techniques: AGA two-sweep iterative method and modified AGA. Successive overrelaxation is applied. The power method, combined with two- or three-term Chebyshev polynomial acceleration, is applied for outer iterations.

6. RESTRICTIONS OR LIMITATIONS

The limits are a maximum of 10 energy groups, 30 horizontal layers and 100 material compositions.

7. TYPICAL RUNNING TIME

The sample problem took 4 minutes, 8 seconds on the IBM 3031 under OS/VS1.

8. COMPUTER HARDWARE REQUIREMENTS

HEXAB-3D runs on the IBM 370/145 and IBM 3031 computers.

9. COMPUTER SOFTWARE REQUIREMENTS

The code is written in FORTRAN IV and Assembler. The FORTRAN IV (G) compiler is required together with the IBM Assembler running under OS/VS1.

10. REFERENCES

a. Included in the documentation:

K. Ivanov, M. Manalova, T. Apotolov, ``IBM User's Guide to HEXAB-3D Code,'' Informal Notes Pr.11-22.07.1987 (March 1991).

K. Ivanov, T. @Apostolov, M. Manalova, ``HEXA-3D: A Three-dimensional Few-Group Coarse-Mesh Diffusion Code for Reactor Calculations,'' Proc. of International Topical Meeting on Advances in Mathematics, Computations and Reactor Physics, Pittsburgh, Pennsylvania (April 28 -- May 2, 1991.)

b. Background information:

K. Ivanov, M. Manalova, T. Apostolov, ``Application of Two-Sweep Iterative Method AGA DSOR in the three-dimensional Hexagonal Programme HEXAB-3D for Group Diffusion Calculations of Fast Breeder Reactors,'' Nuclear Energy 28, Sofia, pp. 13-18 (1990).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one DS/HD 5.25-in. diskette (1.2 MB), containing the source code, sample input and output.

12. DATE OF ABSTRACT

October 1991.