1. NAME AND TITLE
ELAN: Neutron Cross-Section Self-Shielding Code System.
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
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.
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
KEYWORDS: ACTIVATION DETECTORS; DETECTOR RESPONSE; NEUTRON CROSS SECTION PROCESSING; SELF SHIELDING