1. NAME AND TITLE

MARCOPOLO: Code System for Calculating the Radial and Axial Neutron Diffusion Coefficients in One-Group and Multigroup Theory.

2. CONTRIBUTOR

Beijing Institute of Nuclear Engineering, People's Republic of China, through the OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370.

4. NATURE OF PROBLEM SOLVED

MARCOPOLO calculates the radial and axial diffusion coefficients in one-group and multi-group theory for a cylinderized cell (Wigner-Seitz theory) with several concentric zones according to the isotropic shock or linear anisotropic shock hypotheses.

5. METHOD OF SOLUTION

MARCOPOLO allows testing of the degree of approximation of the transport correction in various types of lattices and shows that the axial coefficient may be strongly underestimated in certain cases. This method also allows testing of the simple formulas presented in the past for diffusion coefficients which leads to good results. The problem of the coupling between energy groups, which appears in the calculation of diffusion coefficients (done with zero radial and axial Laplacian), is also analyzed by the present method; it usually appears to be weak.

6. RESTRICTIONS OR LIMITATIONS

The maximum number of concentric zones is 9.

7. TYPICAL RUNNING TIME

On an IBM 3084Q computer, the test case included in the package ran in 28 seconds of CPU time. RSIC made no additional studies of typical running times for MARCOPOLO.

8. COMPUTER HARDWARE REQUIREMENTS

MARCOPOLO is operable on the IBM 360/370 computers. Main storage requirements were 552 K bytes.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

C. Yang and P. Benoist, "Scattering Anisotropy and Neutron Leakage in Reactor Lattices," Nucl. Sci. Eng. 86, 47 (1984).

C. Yang and P. Benoist, "Anisotropie du Choc and Fuites de Neutrons dans un Reseau de Reacteur," CEA-R-5182 (September 1982).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (360KB) DOS diskette which contains the source code and sample problem input.

12. DATE OF ABSTRACT

June 1986.