**1. NAME AND TITLE**

ELF: Monte Carlo Neutron Transport Code System for Cylinders and
Spheres.

**AUXILIARY ROUTINES**

LEC-AWRE: Cross Section Handling Code.

ELF-NEUTRON: Monte Carlo Neutron Transport Code.

ELF-VARI-PYRO: Analysis Code.

**DATA LIBRARY**

UKNLD: Data Library 91 elements.

**2. CONTRIBUTOR**

Shielding Laboratory, CEA/CEN/Fontenay-aux-Roses Nuclear Research Center, now located
at CEA/CEN/Saclay, Gif-sur-Yvette, France.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360.

**4. NATURE OF PROBLEM SOLVED**

ELF was designed to study the propagation of neutrons in cylindrical and spherical geometries
using AWRE cross sections. In cylindrical geometry the external contour can be circular or
polygonal, the limiting conditions at this contour being a vacuum or total reflection.

**5. METHOD OF SOLUTION**

The Monte Carlo method is used to compute the radiation transport. Auxiliary routines are used for the preparation of cross sections, the study of variance, and to further analyze the ELF collision results.

ELF-VARI-PYRO calculates the spectrum and detector responses from ELF-NEUTRON collision results. The calculation of the mean value is associated with a statistical error bar and a normality test.

The UK-AWRE data library is updated periodically and the update is available from CCDN,
Saclay, France.

**6. RESTRICTIONS OR LIMITATIONS**

The following limits apply for 265K storage: 10 elements, 20 materials, 30 meshes, 150 energy
intervals, 200 neutron emission energies, and 100 points defining the radial distribution.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for ELF.

Estimated running time of the sample problem on the IBM 360/91: 5 minutes.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code system is operable on the IBM 360/75/91 hardware configuration. 256K of core
storage is required.

**9. COMPUTER SOFTWARE REQUIREMENTS**

Standard IBM 360 OS Compilers may be used.

**10. REFERENCES**

F. Gervaise, "ELF Program-Description of Utilization," CEA-Note N-1361 (ORNL-tr-2409) (1970).

F. Gervaise, "ELF-NEUTRON Program," CEA-Note N-1255 (ORNL-tr-2519) (1970).

K. Parker, "The Aldermaston Nuclear Data Library as at May 1963," AWRE-O-70/63 (September 1963).

D. S. Norton, "The UKAEA Nuclear Data Library," AEEW-M824 (February 1968).

D. S. Norton and J. S. Story, "UKAEA Nuclear Data Library, January 1967," AEEW-M802.

P. J. Hemmings and S. M. Offord, "Photon Interaction Data in the UKAEA Nuclear Data
Library," AHSB(S)R 109 (1966).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and two (1.2MB) DOS diskettes which contain the
source codes, data libraries, and sample problem input and output.

**12. DATE OF ABSTRACT**

June 1972; reviewed December 1984.

**KEYWORDS: ** MONTE CARLO; NEUTRON; CYLINDRICAL GEOMETRY; SPHERICAL
GEOMETRY