RSICC CODE PACKAGE CCC-707

1. NAME AND TITLE 
PARTISN 2.99: Multi-Dimensional, Time-Independent or Time-Dependent, Multigroup, Discrete 
Ordinates Transport Code System. 

2. CONTRIBUTOR 
Los Alamos National Laboratory, Los Alamos, New Mexico. 

3. CODING LANGUAGE AND COMPUTER 
Fortran 90 and C; Cray, SGI, IBM, HP 9000, Alpha, Intel Linux PC (C00707MNYCP00). 

4. NATURE OF PROBLEM SOLVED 
PARTISN (PARallel, TIme-Dependent SN) is the evolutionary successor to CCC-547/DANTSYS. 
User input and cross section formats are very similar to that of DANTSYS. The linear 
Boltzmann transport equation is solved for neutral particles using the deterministic (SN) 
method. Both the static (fixed source or eigenvalue) and time-dependent forms of the 
transport equation are solved in forward or adjoint mode. Vacuum, reflective, periodic, 
white, or inhomogeneous boundary conditions are solved. General anisotropic scattering 
and inhomogeneous sources are permitted. PARTISN solves the transport equation on 
orthogonal (single level or block-structured AMR) grids in 1-D (slab, two-angle slab, 
cylindrical, or spherical), 2-D (X-Y, R-Z, or R-T) and 3-D (X-Y-Z or R-Z-T) geometries. 

5. MTHOD OF SOLUTION 
PARTISN numerically solves the multigroup form of the neutral-particle Boltzmann 
transport equation. The discrete-ordinates form of approximation is used for treating the
 angular variation of the particle distribution. For curvilinear geometries, diamond 
differencing is used for angular discretization. The spatial discretizations may be 
either low-order (diamond difference or Adaptive Weighted Diamond Difference (AWDD)) or 
higher-order (linear discontinuous or exponential discontinuous). Negative fluxes are 
eliminated by a local set-to-zero-and-correct algorithm for the diamond case (DD/STZ). 
Time differencing is Crank-Nicholson (diamond), also with a set-to-zero fixup scheme. 
Both inner and outer iterations can be accelerated using the diffusion synthetic 
acceleration method, or transport synthetic acceleration can be used to accelerate the 
inner iterations. The diffusion solver uses either the conjugate gradient or multigrid 
method. Chebyshev acceleration of the fission source is used. First-collision source 
treatment options are provided for the elimination of primary ray effects in fixed-source 
calculations. The angular source terms may be treated either via standard PN expansions or 
Galerkin scattering. An option is provided for strictly positive scattering sources.
 Parallelization is performed via a 2-D spatial decomposition, which retains the ability 
 to invert the source iteration equation in a single sweep. 

6. RESTRICTIONS OR LIMITATIONS 
The code is thoroughly variably dimensioned, with memory requirements determined from the 
input parameters. Out-of-core (i.e., disk) storage capability options are provided for 
the flux moments and time-dependent angular fluxes. 

7. TYPICAL RUNNING TIME 
Running time on a single processor is directly related to problem size and to central 
processor and data transfer speeds. On a SGI R10000, a four-group eigenvalue calculation 
of an X-Y-Z model of the Fast Test Reactor (FTR) took 9 seconds. The calculation used 
transport corrected P0 cross sections, an S8 angular quadrature, DD/STZ spatial 
differencing, and a 14x14x30 spatial mesh. Running time on parallel platforms is 
sensitive to the latency and topology of the interconnect, as well as the single 
processor performance. 

8. COMPUTER HARDWARE REQUIREMENTS 
The current release is designed for UNIX-like systems. The specific computers supported 
fall into two categories - long word and short word. The program has been implemented on 
long word Cray J90 and T90 computers. It has also been implemented on Linux, SGI, IBM
 RS/6000, HP9000, and Compaq Alpha short word workstations. The workstation versions use 
double precision arithmetic. The program has been run in parallel on clusters of SGI 
workstations, IBM SP2, and Compaq Alphas. The virtual machine memory must be large enough 
for the problem being executed. On many architectures, stack size limits must be large 
enough to allow the placement of temporary arrays on the stack. 

9. COMPUTER SOFTWARE REQUIREMENTS 
The program is written in ANSI standard F90 with a few C language routines used to 
interface to the Unix operating system. There is no Windows version. PARTISN stresses 
most f90 compilers, so please ensure that the compiler version you are using is at least
 as recent as the one listed below on which the LANL developers ran the code system. 

?Cray CF90 Version 3.0.2.1 
?Lahey-Fujitsu LF95 Fortran Compiler Version 6.0 on Intel PC running Linux 
?IBM XLF Fortran Compiler Version 7.1.0.3 on IBM RS/6000 
?MIPSpro Fortran Compiler Version 7.3.1.2m on SGI 
?Compaq Fortran Compiler V5.5-1877-48BBF on Compaq Alpha under Digital Unix 
RSICC tested this release in parallel and serial modes on an IBM SP3 with the Version 
7.1.0.3 compiler and on an Intel PC running Linux. The non-parallel executable file 
compiled with Lahey/Fujitsu Fortran 95 L6.10a under Red Hat Linux 7.3 is included in the 
distribution file. 
Parallelization is performed using MPI 1.1. The program is designed to run on UNIX-like 
operating systems. Where available, POSIX routines are used to obtain the machine name,
 cross section path, and access rights. Otherwise, system-specific routines must be used. 

In addition to Fortran and C compilers, program building requires GNUmake (Version 3.74 
or later), GNU awk (Version 3.0 or later), and cpp. A Readme file in the top program 
directory contains build instructions. 

PARTISN is modularly structured in a form that separates the input and output (edit) 
functions from the main calculational (solver) section of the code. The code makes use 
of binary, sequential data files, called interface files, to transfer data between modules.
 Standard interface files whose specifications have been defined by the Reactor Physics 
Committee on Computer Code Coordination are accepted, used, and created by the code. A 
free-field card-image input capability is provided for the user. The code provides the 
user with considerable flexibility in using both card-image or sequential file input and 
in controlling the execution of modules. 

10. REFERENCES 
a: included in documentation: 
R. Baker, "Abstract.pdf" (November 2002). 
R. E. Alcouffe, R. S. Baker, J. A. Dahl, and S.A. Turner, "PARTISN User's Guide," Transport
 Methods Group, CCS-4, Los Alamos National Laboratory (November 2002). 
PARTISN -- Introduction and System Overview, Transport Methods Group, CCS-4, Los Alamos 
National Laboratory (November 2002). 
b: background information: 
R. E. Alcouffe, R. S. Baker, F. W. Brinkley, D. R. Marr, R. D. O'Dell, and W. F. Walters,
 "DANTSYS: A Diffusion Accelerated Neutral Particle Code System," LA-12969-M, (1995). 
This report is included in the distribution file with the name C547.PDF. 
R. S. Baker and K. R. Koch, "An SN Algorithm for the Massively Parallel CM-200 Computer,
" Nucl. Sci. and Eng., 128, 312 (1998). 
R. S. Baker ,"A Block Adaptive Mesh Refinement Algorithm for the Neutral Particle 
Transport Equation," Nucl. Sci. and Eng., 141, 1 (2002). 

11. CONTENTS OF CODE PACKAGE 
Included are the references in 10.a and a CD which includes PARTISN source files, a Linux 
executable, installation procedures, a test case, and PARTISN and DANTSYS reports in a 
GNU compressed tar file. 

12. DATE OF ABSTRACT 
January 2003. 

KEYWORDS: ADJOINT; DISCRETE ORDINATES; GAMMA-RAY; MULTIGROUP; NEUTRON; SPHERICAL GEOMETRY; 
SLAB; CYLINDRICAL GEOMETRY; WORKSTATION; COMPLEX GEOMETRY