**1. NAME AND TITLE**

DANTSYS 3.0: One-, Two-, and Three-Dimensional, Multigroup, Discrete-Ordinates Transport Code System.

**2. CONTRIBUTOR**

Los Alamos National Laboratory, Los Alamos, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN 77 (99.9%); C (0.1%); Cray, SUN Sparcstation, IBM RS/6000, Hewlett Packard 9000, and Silicon Graphics. (C00547/MFMWS/01).

**4. NATURE OF PROBLEM SOLVED**

CCC-707/ PARTISN (PARallel, TIme-Dependent SN) is the evolutionary successor to DANTSYS and runs on a variety of computer platforms. User input and cross section formats are very similar to that of DANTSYS, and the LANL developers recommend the use of PARTISN.

DANTSYS replaces TWODANT-SYS and includes five major codes. ONEDANT solves the one dimensional multigroup transport equation in plane, cylindrical, spherical and two-angle plane geometries. TWODANT solves the two-dimensional multigroup transport equation in x-y, r-z, and r-theta geometries. TWOHEX solves the two-dimensional multigroup transport equation on equilateral triangular meshes in the x, y plane. THREEDANT solves the three-dimensional multigroup transport equation in x-y-z and r-z-theta geometries. TWODANT/GQ solves the two-dimensional transport equation in x-y and r-z geometries on general quadrilaterals. DANTSYS accepts the basic multigroup cross sections for isotopes, in either of the standard interface files (ISOTXS or GRUPXS) or in a card-image library whose form is referred to as Los Alamos, ANISN, or FIDO. PSR-317/TRANSX2.15 will translate MATXS libraries into these formats. ONEDANT, TWODANT and TWOHEX were included in TWODANT-SYS, THREEDANT and TWODANT/GQ were added to the package in August 1995 with the first public release of DANTSYS. In March 1997 subroutines perr and tolcm were modified to correct a problem of overfilling a string (SITOP).

**5. METHOD OF SOLUTION**

ONEDANT, TWODANT, TWODANT/GQ and THREEDANT use the discrete ordinates approximation for treating the angular variation of the particle distributions. The diamond difference scheme is used for phase space discretization. In TWODANT and THREEDANT there is an option to use the adaptive weighted diamond method. Both inner and outer iterations are accelerated using the diffusion synthetic acceleration method. TWOHEX uses the discrete ordinates form for treating the angular variation of the particle distribution, and a nodal scheme is used for phase space discretization. Both inner and outer iterations are accelerated using the Chebyshev acceleration method.

**6. RESTRICTIONS OR LIMITATIONS**

The codes are variably dimensioned with a flexible, sophisticated data management and transfer capability.

**7. TYPICAL RUNNING TIME**

Running time for each solver is directly related to problem size and the platform bing used. In ONEDANT a modest sized problem of 30 groups and 100 mesh points runs in less than 2 seconds on a CRAY-YMP. In TWODANT a 31 x 60 mesh, S4, 4 group problem takes 7 seconds on the YMP. In THREEDANT a 32 x 32 x 20 mesh, S8, 4 group problem takes 52 seconds to converge on a YMP and 5 minutes on an IBM RS/6000/590. A four group calculation of the eigenvalue of a midplane whole core model of the Fast Test Reactor took about 20 seconds on a YMP.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code runs on Cray YMP, SUN Sparc Station IPX, IBM RS/6000 Model 590, Hewlett Packard 9000 Model 735, and Silicon Graphics-cpu IP22-mips.

**9. COMPUTER SOFTWARE REQUIREMENTS**

DANTSYS requires a Fortran 77 compiler; a C-language preprocessor (cpp); a C-compiler (cc); and GMAKE (GnuMake from Free Software Foundation). Please be advised that in our experience some compiler versions on the various platforms are deficient in the sense that either the code will not compile or else bad assembly code is generated. We list the operating systems and Fortran compilers under which the code met our QA requirements.

1. CRAY-(UNICOS 7.0.6.1/CF77-RELEASE 6.0.3.11)

2. SUN-(SUNOS 4.1.2/F77 Version 2.0.1)

3. IBM RS/6000-(AIX 2.3/XLF RELEASE 03.02.0002.0001)

4. Hewlett Packard 9000-(HP-UX A.09.05/F77-HP UX10.0)

5. Silicon Graphics-(IRIX 5.2/F77 RELEASE 5.2).

**10. REFERENCE**

"DANTSYS 3.0 Modifications" (March 17, 1997).

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 Transport Code System," LA-12969-M (June 1995).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and 1 dc 6150 tape cartridge in compressed Unix tar format, which includes GnuMake files, source, and test problems.

Los Alamos National Laboratory informed us that the DANTSYS documentation is available electronically through the LANL World Wide Web pages at http://www-xdiv.lanl.gov/XTM. Select "Our Services and Products," then "DANTSYS", then "LA12969-M On line." It is also available from the RSICC WWW pages at http://www-rsicc.ornl.gov, click on RSICC, then on Software, then On-line Documentation. DANTSYS is a one-, two-, and three-dimensional, multigroup, discrete-ordinates transport code system, which includes five major codes: ONEDANT, TWODANT, TWOHEX, THREEDANT, and TWODANT-GQ.

DANTSYS runs on the following platforms: CRAY-YMP, Sun SparcStation IPX, IBM RS/6000, HP, and Silicon Graphics under Unix-based operating systems. A Fortran 77 compiler, a C-language preprocessor (cpp), a C-compiler, and GMAKE (GnuMake from Free Software Foundation) are required to install the package which is distributed on 1 DC 6150 (150 MB) cartridge, 4-mm or 8-mm tape in compressed tar format.

**12. DATE OF ABSTRACT**

April 1990; revised May 1992 and November 1992, February 1994, April 1994, August 1995, March 1997.

**KEYWORDS: ** ADJOINT; DISCRETE ORDINATES; GAMMA-RAY; MULTIGROUP;
NEUTRON; SPHERICAL; SLAB; CYLINDRICAL GEOMETRY; WORKSTATION; ONE-DIMENSION; TWO-DIMENSIONS; COMPLEX GEOMETRY