1. NAME AND TITLE
SNOW: Two-Dimensional Discrete Ordinates Multigroup Transport Code System in Plane
and Cylindrical Geometry with Isotropic and Anisotropic Scattering.
Karlsruhe Nuclear Research Center, Karlsruhe, Germany.
OECD NEA Data Bank, Gif-sur-Yvette, France.
3. CODING LANGUAGE AND COMPUTER
FORTRAN IV and Assembler Language; IBM 360/370.
4. NATURE OF PROBLEM SOLVED
SNOW was designed to solve the two-dimensional multi-group neutron transport equation by
the discrete ordinates (SN) method. Geometries included are (x,y)-plane and (r,z), (r, theta)-cylinder, isotropic and anisotropic scattering and several other special options are permitted. Three
methods of convergence acceleration are incorporated.
5. METHOD OF SOLUTION
The discretization of the Boltzmann equation is effected by the diamond difference scheme of
B. Carlson and K. Lathrop and the numerical integration of the angle-dependent fluxes by means of
B. Carlson and C. E. Lee's procedure. In view of the large dimensions of the matrices the
introduction of effective convergence accelerations was essential for the external and internal
iterations. In addition to the rebalancing and Tschebyscheff accelerations a further option was
incorporated which, without great additional effort, enabled the calculation of the problem to be
carried out with different step widths and different SN orders and also with a favorable combination
of step widths produced an approximately 50% saving of computer time (rough lattice technique).
Depending on the required results, the user can feed in a ``flux-oriented'' accuracy interrogation
or one based on the eigenvalue keff. The following further options are available: calculation of
inhomogeneous problems (foreign source), use of bucklings, anisotropy, adjoint calculation,
various boundary conditions.
6. RESTRICTIONS OR LIMITATIONS
7. TYPICAL RUNNING TIME
No typical running time has been established.
8. COMPUTER HARDWARE REQUIREMENTS
The code system was designed to run on the IBM 360/370 computers.
9. COMPUTER SOFTWARE REQUIREMENTS
The code packaged is operable on the IBM 360/370 computers.
G. Gunther and W. Kinnebrock, "SNOW: A Two-Dimensional SN Program for Solving the
Neutron-Transport Equation in Rectangular and Cylindrical Geometry," EURFNR-1130 (KFK
1826) (July 1973).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document and one (1.2MB) DOS diskette which contains the source
codes and sample problem input and output.
12. DATE OF ABSTRACT
KEYWORDS: TWO-DIMENSIONS; MULTIGROUP; CYLINDRICAL GEOMETRY; NEUTRON; GAMMA-RAY; DISCRETE ORDINATES