**1. NAME AND TITLE**

FINELM: Multigroup Finite Element Diffusion Code System.

**2. CONTRIBUTOR**

Eidg. Institut für Reaktorforschung Würenlingen, Switzerland, through the OECD NEA Data Bank, Gif-sur-Yvette, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; VAX 8810, Cray XMP, Sun workstations.

**4. NATURE OF PROBLEM SOLVED**

FINELM solves the Neutron Diffusion Equation in X-Y, R-Z, R-theta, X-Y-Z and R-theta-Z geometries.

**5. METHOD OF SOLUTION**

FINELM solves the Neutron Diffusion Equation using the method of Finite Elements. Lagrangian elements of linear or higher degree to approximate the special flux distribution have been provided. The method of dissections, coarse mesh rebalancing and Chebyshev acceleration techniques are available. Simple user defined input is achieved through extensive input subroutines. The input preparation is described followed by a program structure description; sample cases are given.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

NEADB noted the following run times on a VAX 8810: 1a - 27s; 1b - 3m,3s; 2 - 15s; 3 - 12s; 4a - 3s; 4b - 3s; 55 - 5s; 6 -4s; 7 - 3s; 8 - 3s.

**8. COMPUTER HARDWARE REQUIREMENTS**

FINELM is runs on the VAX 8810, Sun workstations and Cray XMP.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran 77 compiler is required.

**10. REFERENCES**

J. Stepanek and D. M. Davierwalla. Chapters 3 and 5 of FINELM Draft Manual, May 17, 1990.

Comparison Tables for Two 3-Dimensional Cases on Cray, SUN and VAX. Informal Notes.

C. E. Higgs and D. M. Davierwalla, "FINELM: A Multigroup Finite Element Diffusion Code," EIR-Bericht Nr. 459, Würenlingen, Switzerland (April 1982).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one DS/HD 5.25-inch diskette (1.2 mb) which contains the source code and sample problems.

**12. DATE OF ABSTRACT**

May 1986; March 1991.

**KEYWORDS: ** FINITE ELEMENT METHOD; DIFFUSION THEORY;
COMPLEX GEOMETRY