RSIC CODE PACKAGE CCC-254


1. NAME AND TITLE

ANISN-ORNL: One-Dimensional Discrete Ordinates Transport Code System with Anisotropic
Scattering.

ANISN supersedes DTF-II (NAA-SR-10951, March 1966) which followed a series of
developmental efforts over a period of years.  An early version, DSN, was developed
in the FLOCO language by Bengt Carlson of the Los Alamos Scientific Laboratory.
A revision of DSN, called DTK, was written to incorporate improved convergence
technique and ease of operation.  DTF was a FORTRAN version of DTK written by UNC and
LASL personnel. DTF-II evolved from DTF at Atomics International and in turn evolved
into ANISN.



2. CONTRIBUTORS

Oak Ridge National Laboratory, Oak Ridge, Tennessee (C00254I303300, C00254CYOMP00,
C00254IRISC01).

Infintum Sciences Limited, Ottawa, Ontario, Canada (C00254D0VAX00).  

Battelle, Columbus, Ohio (C00254PC38601).



3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 3033 (C00254I303300); CRAY (C00254CYOMP00), VAX (C00254D0VAX00);
FORTRAN 77, PC 386/486 (C00254PC38601), IBM RS/6000 (C00254IRISC01).



4. NATURE OF PROBLEM SOLVED

ANISN 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 space and energy
dependent flux generated in solving the transport equation.  The workstation version
of ANISN-ORNL is also included in CCC-650/DOORS 3.1.



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 ANISN 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. ANISN also
includes a technique for handling general anisotropic scattering, pointwise convergence
criteria, and alternate step function difference equations that effectively remove the
oscillating flux distributions sometimes found in discrete ordinates solutions.
Improvements are made for the Cray and IBM RISC versions.  They include the addition
of 3 arrays; 29$ (regions by interval) 59$ (unit # for input and output), and 60$
(Kword of storage).



6. RESTRICTIONS OR LIMITATIONS

Problem size is limited only by machine size.



7. TYPICAL RUNNING TIME

Depending on problem size, type, and convergence, running time has varied from less
than one minute to several hours. On the IBM 3033 the adjoint air neutron sample
problem required about 45 seconds. The other ten sample cases ran in about 30 seconds.

On the Cray XMP-14, the adjoint problem ran in .2 minute.  The 10 sample problems
took .11 minute.

On a Northgate 486/66 most sample problems ran in 5 seconds or less.

The IBM RS/6000 took approximately 5 seconds to run the 10 sample problems.



8.  COMPUTER HARDWARE REQUIREMENTS

ANISN-ORNL is operable on the IBM 3033, CRAY XMP-2, VAX family, PC 386 or IBM RISC
6000 computers.

The PC version runs on 386 (with 387 co-processor) or 486 personal computers.
It requires 4 megabytes of memory, 20 MB of disk space, and at least 7 of extended on
expanded memory and a math co-processor.  Faster run time is achieved with 6 or more
MB of memory.



9.  COMPUTER SOFTWARE REQUIREMENTS

The IBM 3033 version runs under OS/VS2 (MVS) using the VS FORTRAN compiler with the
'LANGLVL(66)' option or a FORTRAN H compiler.  The CRAY version uses the CFT compiler
with FORTLIB under CTSS; under UNICOS, the CFT77 compiler is used.  The VAX version runs
under VMS 4.6 using the VMS FORTRAN (version 4.7) compiler with the /NOOPTIMIZE and
/NOF77 switches.  The Lahey FORTRAN F77L-EM/32 version 5.1 compiler was used with the
virtual memory linker to create the executables under DOS 6.2.  The programs will run
under DOS 3.3 or higher.



10. REFERENCES

W. W. Engle Jr., and F. R. Mynatt, "A Comparison at Two Methods of Inner Iteration
Convergence Acceleration in Discrete Ordinates Codes," Transactions of ANS,
Volume II, No. 1 (June1968).

ANISN Updates and Additional Information (1971-1977).

L. M. Petrie, "Informal Notes on Use of ITIME Assembler Routine in IBM Version, "ORNL
(May 1973).

"Modifications Included in the July 1988 ANISN Updates," ORNL Informal Notes (July 1988).

"README.1ST," IBM RISC Implementation Notes (4/94).

"README.RSI," PC Implementation Notes (6/94).

W. W. Engle, Jr., "ANISN, A One-Dimensional Discrete Ordinates Transport Code
with Anisotropic Scattering," K-1693 (March 1967).

R. W. Roussin, "Using ANISN to Reduce the DLC-2/100-Group Cross-Section Data to
a Smaller Number of Groups," ORNL-TM-3049 (May 1969).

W. W. Engle, M. A. Boling, and B. W. Colston, "DTF-II, A One-Dimensional,
Multigroup Neutron Transport Program," NAA-SR-10951 (March 1966).



11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and a diskette which contains the source codes,
JCL, sample input and output.  Executables are included only in the PC release.
Each version is available on one DS/HD 3.5-inch (1.44 MB) diskette in DOS format.



12. DATE OF ABSTRACT

January 1968; updated October 1975, December 1982, December 1983, March 1985, August
1985, July 1988, April 1989, February 1991, April 1991, June 1994, May 1995.



KEYWORDS: DISCRETE ORDINATES; NEUTRON; GAMMA-RAY; ONE-DIMENSION; MULTIGROUP;
CYLINDRICAL GEOMETRY; ADJOINT; MICROCOMPUTER; WORKSTATION