1. NAME AND TITLE

ANISN/PC: Multigroup One-Dimensional Discrete Ordinates Transport Code System with Anisotropic Scattering. RSIC recommends CCC-254/ANISN-ORNL for most applications.

AUXILIARY ROUTINES

APE: Interactively generates an input file for ANISN/PC.

LMOD: Selects materials from a master ASCII CCCC ISOTXS file and places them on a CCCC file for input to ANISN/PC.

ANTOPC: Converts ANISN-formatted cross sections to CCCC ISOTXS format for use with ANISN/PC.

ANTOAPE: Converts ANISN-formatted cross sections to CCCC ISOTXS for APE (does not use repeat option.)

Data Library:

FLUNGP: 21-Group photon cross section master library in CCCC ISOTXS format derived from DLC-86/FLUNG.

ANISN/PC follows a series of developmental efforts over a period of years (see CCC-254/ANISN-ORNL). It is a modification of CCC-255/ANISN-W, the Westinghouse version, which was based on the Oak Ridge National Laboratory (ORNL) work. A subset of DLC-75/ BUGLE80, in either ANISN or ISOTXS format, is available on diskette for use with the workstation version of ANISN/PC.

2. CONTRIBUTORS

EG&G Idaho, Inc., Idaho Falls, Idaho.

Los Alamos National Laboratory, Los Alamos, New Mexico.

University of Cincinnati, Cincinnati, Ohio.

3. CODING LANGUAGE AND COMPUTER

Fortran 77, IBM PC and workstation.

4. NATURE OF PROBLEM SOLVED

ANISN/PC solves the one-dimensional Boltzmann transport equation for neutrons or gamma rays in slab, sphere, or cylinder geometry. The source may be fixed, fission, or a subcritical combination of the two. Criticality search may be performed on any one of several parameters. Cross sections may be weighted using the energy dependent flux generated in solving the transport equation.

The CCC-514/ANISN-PC implementation does NOT read an ANISN library in binary format. When INEL did the conversion to PC, they modified the code to read CCCC ISOTXS cross section format with a limit of 25 energy groups. One can input ASCII ANISN-format data in the 14** array in the ANISN-PC code. Although it is awkward to edit large data files, it is the only way to read ANISN-format data in the ANISN-PC code.

5. METHOD OF SOLUTION

The solution technique is an advanced discrete ordinates method which represents a generalization of the method originated by G. C. Wick and greatly developed and extended to curvilinear geometry by B. G. Carlson at Los Alamos Scientific Laboratory.

ANISN was designed to solve deep-penetration problems in which angle-dependent spectra are calculated in detail. The principal feature that makes it suitable for such problems is the use of a programming technique with optional data-storage configurations which allows execution of small, intermediate, and extremely large problems. It also includes a technique for handling general anisotropic scattering. For ANISN/PC the standard source iteration method, accelerated by up to two single scale factors, is used for outer iterations. Inner iterations are accelerated either by a stabilized variable-mesh rebalance scheme or by a linear diffusion synthetic scheme. A noniterative matrix inversion technique based on a reflection principle is used for diffusion theory inner iterations.

6. RESTRICTIONS OR LIMITATIONS

The energy group limit is 25 for the PC version.

Problem size is limited by machine size. The workstation version is machine independent except for the UNIX timer and will work with up to 121 energy groups in approximately 2.6 MB of computer memory.

7. TYPICAL RUNNING TIME

Run times range from a few minutes to several hours, depending on the problem. In general, a 1.5 to 2 orders of magnitude increase in run time is seen between ANISN/PC on an IBM PC XT and ANISN-W on a CDC Cyber 176.

8. COMPUTER HARDWARE REQUIREMENTS

The minimum hardware requirements for ANISN/PC are: an IBM PC or compatible, the 8087 math coprocessor chip, a 10 MB fixed disk, 640 K Random Access Memory.

9. COMPUTER SOFTWARE REQUIREMENTS

The Ryan McFarland IBM Professional Fortran compiler was used to compile the programs under PC/DOS. The PLINK86-Plus overlay linker was used to create an executable ANISN file of approximately 640 K bytes. The PC/DOS linker was used to link the APE32 and LMOD programs. The executable files are included in the package. The Lahey Fortran 77 compiler was used to create the executable files for the ANTOPC and ANTOAPE utility programs.

10. REFERENCES

a. Included in package:

Informal Note from RSIC (September 1, 1994).

D. Kent Parsons, "Refinement for Spherical Geometry Problems with Low Order Quadrature," Letter from LANL (June 6, 1990).

D. Kent Parsons, "ANISN/PC MANUAL," EGG-2500 (December 1988).

b. Background information:

W. W. Engle, Jr., "A User's Manual for ANISN: A One-Dimensional Discrete Ordinates Transport Code with Anisotropic Scattering," K-1693 (1967).

R. G. Soltesz and R. K. Disney, "Nuclear Rocket Shielding Methods, Modification, Updating, and Input Data Preparation, Vol. 4, One-Dimensional Discrete Ordinates Transport Technique," WANL-PR-(LL)-034 (August 1970).

R. K. Disney, et al., "ANISN-W, WANL-TME-2778 (February 1971). R. G. Soltesz, "Revised WANL ANISN Program User's Manual," WANL-TM1-1967 (Supplement 1969).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document, source codes for both PC and workstation versions, sample case input and output, and an executable file for the PC version. One DS/HD (1.2 MB) diskette is needed to transmit all files in compressed format.

12. DATE OF ABSTRACT

July 1987, revised September 1989, August 1990 and September 1994.