1. NAME AND TITLE

ELAN: Neutron Cross-Section Self-Shielding Code System.

2. CONTRIBUTOR

United Kingdom Atomic Energy Authority, Winfrith, Dorchester, Dorset, England, through the OECD NEA Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

EGTRAN (Dialect of Fortran II); ICL KDF9.

4. NATURE OF PROBLEM SOLVED

ELAN was developed for use in the field of integral neutron energy spectrum measurement. It is a neutron cross section processing code which calculates: point by point neutron cross sections from resonance parameters; production of group-averaged cross sections for bare detectors (slab, cylindrical and sandwich geometries); cut-off energies of filters; and shielded and self-shielded reaction rates in neutron foil activation detectors and sandwich foil packs.

5. METHOD OF SOLUTION

The Breit-Wigner single level formula is used to obtain cross-section data from resonance parameters. Cut-off energies of filters are evaluated using Nisle's first approximation to thermal flux depression and unperturbed neutron energy spectrum. The sandwich technique as described by Ehret, and a variation on this which has been adopted simply because some elements cannot be made up into a form suitable for sandwiches, are used in ELAN.

6. RESTRICTIONS OR LIMITATIONS

Storage is allocated within ELAN to allow calculations to be made using 1000 energy mesh points, i.e., storage for 1000 foil and filter cross sections, and 1000 fluxes, with up to 30 different energy groups. It is possible to use up to 50 sets of resonance parameters in RESPAR and up to 250 transmission factors in CYLGEO. In subroutine GPAVGS, provision is made to store boundaries for up to 100 new groups. The output of various quantities such as cross sections calculated from RESPAR, point shielded cross sections from SLABGE and transmission factors is limited by the input restrictions.

7. TYPICAL RUNNING TIME

ELAN runs in about 15 minutes.

8. COMPUTER HARDWARE REQUIREMENTS

ELAN is operable on the ICL KDF9 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

An EGTRAN (Fortran II) compiler is required. It uses the EGDON operating system or monitor.

10. REFERENCE

E. J. Maunders, "A Description of the ELAN Computer Code," AEEW-M 621 (March 1966).

11. CONTENTS OF CODE PACKAGE

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

12. DATE OF ABSTRACT

March 1984.