RSICC CODE PACKAGE CCC-762

1.         NAME AND TITLE

ATTILA Ver2:   3D Multigroup Sn Neutron Transport Code.

2.         CONTRIBUTORS

Los Alamos National Laboratory, Los Alamos, New Mexico through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3.         CODING LANGUAGE AND COMPUTER

FORTRAN 95 with some C preprocessor commands. Unix Workstations, Pentium computers (C00762MNYCP00).

4.         NATURE OF PROBLEM SOLVED

ATTILA Version 2 is a 3D multigroup transport code with arbitrary order anisotropic scatter. The transport equation is solved in first order form using a tri-linear discontinuous spatial differencing on an arbitrary tetrahedral mesh. The overall solution technique is source iteration with DSA acceleration of the scattering source. Anisotropic boundary and internal sources may be entered in the form of spherical harmonics moments. Alpha and k eigenvalue problems are allowed, as well as fixed source problems. Forward and adjoint solutions are available. Reflective, vacuum, and source boundary conditions are available. ATTILA Version 2 can perform charged particle transport calculations using slowing down (CSD) terms. ATTILA Version 2 can also be used to perform infra-red steady-state calculations for radiative transfer purposes.

5.         METHOD OF SOLUTION

ATTILA Version 2 uses a standard spatial sweep with source iteration. The sweep equations are solved within each tetrahedron using LU decomposition on a 4x4 matrix.

6.         RESTRICTIONS OR LIMITATIONS

Only steady-state problems are supported, there is no time-dependent mode available at present.

7.         TYPICAL RUNNING TIME

Solution time on a 200 MHz SGI Octane workstation is approximately 4 micro~s per phase space cell using the currently installed linear discontinuous spatial differencing.

8.         COMPUTER HARDWARE REQUIREMENTS

The system has been built on SUN-Solaris, IBM 590 AIX, Cray YMP, SGI IRIX64, and the INTEL Pentium.

9.         COMPUTER SOFTWARE REQUIREMENTS

A Unix/Linux operating system with a FORTRAN compiler is required.

10.        REFERENCES

J. M. McGhee and T. A. Wareing, “Attila Version 2: Users Manual,” Los Alamos National Laboratory, Los Alamos, NM 87544 (DRAFT).

11.        CONTENTS OF CODE PACKAGE

The package is transmitted on a CD in a .tar format file which includes documentation, source files and examples.  No executables are included with the package.

12.        DATE OF ABSTRACT

August 2012.

KEYWORDS:       MULTIGROUP, NEUTRONS, SN METHOD