**1. NAME AND TITLE**

SNEX: A One-Dimensional Single Group Discrete Ordinates Transport Code System.

**2. CONTRIBUTOR**

Los Alamos National Laboratory, Los Alamos, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; CDC.

**4. NATURE OF PROBLEM SOLVED**

SNEX exactly solves the spatial single group, one-dimensional (plane, cylinder, sphere) discrete
ordinates transport equations with diamond approximation for the angular fluxes. Its purposes are to
provide a standard for comparisons of spatial differencing schemes as well as an exact numerical
solution to the discrete ordinates equations in one-dimensional geometries.

**5. METHOD OF SOLUTION**

SNEX solves the single group transport equation with isotropic scattering for specified left and
right boundary conditions. Full solutions are generated by numerically integrating the inhomogeneous
source terms and adding them to the homogeneous (analytic) solutions in the standard fashion. Simple
relationships between angular quadratures permit application of the method to plane, cylindrical, and
spherical geometries.

**6. RESTRICTIONS OR LIMITATIONS**

Analysis is confined to isotropic scattering.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for SNEX.

**8. COMPUTER HARDWARE REQUIREMENTS**

SNEX is operable on the CDC computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCE**

B. R. Wienke, "SNEX: Semianalytic Solution of the One-Dimensional Discrete Ordinates (S_{n})
Transport Equations with Diamond Differenced Angular Fluxes," LA-7879-MS (June 1979).

**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**

January 1982.

**KEYWORDS: ** ONE-DIMENSION; DISCRETE ORDINATES; CYLINDRICAL GEOMETRY;
SLAB; SPHERICAL GEOMETRY; NEUTRON; GAMMA-RAY; ONE-VELOCITY