**1. NAME AND TITLE**

DIAMANT2: Multigroup Two-Dimensional Discrete Ordinates Transport Code System for
Triangular Geometry, Release 2.0.

DIAMANT2 follows DIAMANT, development based on the SNOW code of C.E.N./S.C.K., Mol,
Belgium.

**2. CONTRIBUTOR**

Nuclear Research Center, Karlsruhe, Federal Republic of Germany through the NEA Data Bank,
Issy-les-Moulineaux, France.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN 77; PC 386 (C00414/PC386/00).

**4. NATURE OF PROBLEM SOLVED**

DIAMANT2 solves the two-dimensional static multigroup neutron transport equation in planar
regular triangular geometry. Both regular and adjoint, inhomogeneous and homogeneous problems
subject to vacuum, reflective or input specified boundary flux conditions are solved. Anisotropy is
allowed for the scattering source. Volume and surface sources are allowed for inhomogeneous
problems.

**5. METHOD OF SOLUTION**

The discrete ordinates approximation for the angular variable is used in finite difference form which is solved with a diamond difference approximation. Spatial discretization is performed on a mesh, composed of equilateral triangles. Negative fluxes are eliminated by a step scheme algorithm. Standard inner (within-group) iterative cycles are accelerated by global rebalancing.

DIAMANT2 v. 2.00 eliminates negative flux values using a step scheme algorithm.

**6. RESTRICTIONS OR LIMITATIONS**

Variable dimensioning is used so that any combination of problem parameters leading to a working
array less than NCMAX can be accommodated. On most computers, NCMAX can be as large as some
hundred thousand words. The remaining maximum values are specified by a parameter statement and
can easily be changed.

**7. TYPICAL RUNNING TIME**

On a Northgate 486/66, the run time for the included sample problem was 9 minutes 32 seconds,
using an executable created with Lahey FORTRAN F77L-EM/32 v. 5.1 under MS-DOS 6.2. The run
time was 1 hour 29 minutes 13 seconds using the included sample input problem and an executable
created with MS FORTRAN v. 5.00 under OS/2 v.2.1. On an IBM RS/6000 model 250 the run time
was 17 minutes 15 seconds using the included sample problem.

**8. COMPUTER HARDWARE REQUIREMENTS**

DIAMANT2 is operable on IBM PC's and compatibles, and UNIX workstations (with minimal
source changes).

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran 77 compiler is required for DIAMANT2 v. 2.00. The executable included in package
was created with Lahey F77L-EM/32 v 5.1 compiler under MS DOS 6.2.

**10. REFERENCE**

K. Kufner, J. Burkhard, R. Heger, "An Updated FORTRAN-77 Version of the 2-D Static Neutron
Transport Code DIAMANT2 for Regular Triangular Geometry," KFK 4133 (June 1987).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one DS/HD (1.44 MB) diskette which contains the
source code, sample input/output, information files, and the executables written in self-extracting
compressed DOS files.

**12. DATE OF ABSTRACT**

February 1982; updated January 1983, September 1983, updated October 1994.

**KEYWORDS: ** MULTIGROUP; NEUTRON; TWO-DIMENSIONS; TRIANGULAR MESH;
DISCRETE ORDINATES; MICROCOMPUTER