1. NAME AND TITLE

DLS: Two-Dimensional Shielding Calculational System with Diffusion Theory and Line-of-Sight Method.

2. CONTRIBUTOR

INTERATOM, Bensberg/Koln, Federal Republic of Germany, via the OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; CDC 6400.

4. NATURE OF PROBLEM SOLVED

The neutron flux is calculated in a two-dimensional reactor-shield system. Rotationally symmetrical geometries with gaps or other cavities, which often appear in practical shielding problems, can be investigated conveniently with DLS.

5. METHOD OF SOLUTION

DLS is a two-dimensional diffusion calculational system which uses the line-of-sight technique for the treatment of transport in cavities.

Within material-filled regions, diffusion theory is used, while cavities are treated using the line-of-sight method. The numerical solution of the diffusion equation is based upon balance formulae for all volume elements containing terms for source, absorption, and leakage. At the boundary of a cavity, the term for the entering currents used in the balance equation include the contributions of all other elements at the boundary of the cavity which can be seen from the element considered. These contributions are calculated with the aid of leakage factors and view factors. The leakage factors describe the ratio between the leaving current and the flux density. Various options are available to calculate these leakage factors. The view factors describe the probability that a neutron leaving the cavity surface of an arbitrary volume element hits the considered volume element directly. The calculation of the factors proceeds upon the assumption that the neutrons emitted into the cavity will have a cosine-shaped directional distribution.

6. RESTRICTIONS OR LIMITATIONS

DLS is designed for r-z geometry. Only cavities with strictly rectangular cross sections can be considered. Maximum number of: energy groups26, view factors20000, cavities5, materials15. The sum of radial and axial mesh intervals may not exceed 170. The total mesh number is restricted by machine size.

7. TYPICAL RUNNING TIME

10 to 40 minutes for practical reactor shields (26 groups).

8. COMPUTER HARDWARE REQUIREMENTS

DLS was designed for the CDC 6600 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A FORTRAN IV compiler is required.

10. REFERENCES

G. Gronefeld, "Program DLS," ORNL-tr-4007 (INTERATOM--Nr. 479) (May 1973).

V. H. Vossebrecker, "Two-Dimensional Shielding Calculations Using a Combination of Diffusion Theory and Line-of-Sight Method," Atomkernenergie 19, Series 1, 14-16 (1972).

G. Gronefeld, "Corrections to DLS."

D. Luigs, "New System Routine RTRN," INTERATOM Notice Nr. 33.4.1.

D. Luigs, "Notice Number 33.4.1: New System Routine RTRN," INTERATOM Notice Nr. 33.34.2, (March 1971).

D. Luigs, "Change in the Required Length in Overlay Programs," INTERATOM Notice Nr. D-A378 (June 1970).

H. Baur, "System Routine LAB," INTERATOM Notice Nr. 33.205.8 (September 1971).

D. Luigs, "Variable Dimensioning under Utilization of Blank Common," INTERATOM Notice Nr. 33.601 (August 1972).

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

May 1973; updated October 1978 and February 1983; reviewed January 1985.