**1. NAME AND TITLE**

DTK: One-Dimensional Multigroup Neutron Transport Code System.

DTK was developed from CCC-42/DTF-IV.

**2. CONTRIBUTOR**

Karlsruhe Nuclear Research Center (GFK), Karlsruhe, West Germany.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

The linear, time-independent, Boltzmann equation for particle transport is solved for the energy, space, and angular dependence of the particle distribution in one-dimensional slabs, cylinders, and spheres. Independent source or eigenvalue (multiplication, time absorption, element concentration, zone thickness or system dimension) problems are solved subject to vacuum, reflective, or periodic boundary conditions.

**5. METHOD OF SOLUTION**

DTF-IV is designed to solve, by the methods of discrete ordinates (Carlson S_{N}), the
multigroup, one-dimensional (plane, cylinder, sphere) Boltzmann transport equation. Anisotropic
scattering is represented by Legendre polynomial expansion of the differential scattering cross
section. A complete energy-transfer scattering matrix is allowed for each Legendre component of
scattering cross-section matrices.

Energy dependence is treated by the multigroup approximation and angular dependence by a general discrete ordinates approximation. Anisotropic scattering is approximated by a truncated spherical harmonics expansion of the scattering kernel. Within-group scattering and up-scattering (if any) iteration processes are accelerated by system-wide renormalization procedures.

General anisotropic scattering capability is provided in each of the three geometries, up-scattering convergence acceleration is used, an optional group- and point-wise convergence test is available, and a neutron conserving negative flux correction routine is used.

DTK differs from DTF-IV in that: the input has been simplified; a new nonconstant initial
source has been built in; a variety of buckling options has been incorporated; Tchebychew
extrapolation has been built in for the outer iterations; and capability of passing fluxes from one
case to another has been added. If either S_{N}-order or the number of mesh-points do not agree,
DTK is able to interpolate. The Karlsruhe NUSYS cross section code system is not in the package.

PSR-86/GAMLEG provides cross sections for photon transport problems in a form suitable for input to DTK.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

Running time depends on the number of groups, the number of space points, the order of angular approximation, the precision desired and the initial guess.

**8. COMPUTER HARDWARE REQUIREMENTS**

DTK is operable on the IBM 360/370 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required. A nonstandard timing subroutine is included in the package.

**10. REFERENCE**

C. Gunther, W. Kinnebrock, "The DTK One-Dimensional Transport Program," KFK-Bericht 1381, EURFNR-927 (March 1971).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and sample problem input and output.

**12. DATE OF ABSTRACT**

February 1974; updated July 1975.

**KEYWORDS: ** DISCRETE ORDINATES; NEUTRON; GAMMA-RAY; ONE-DIMENSION;
MULTIGROUP