**1. NAME AND TITLE**

DTF-INDIA: Multigroup Neutron Transport Discrete Ordinates Code System with One-Dimensional, Anisotropic Scattering.

An early version of this code, DSN, was developed in the FLOCO language by Bengt Carlson of
LASL. A revision of DSN, called DTK, was written to incorporate convergence technique and ease
of operation. DTF is the Fortran version of DTK written by UNC and LASL personnel. DTF-IV was
a complete revision of DTF. The major features of the revision were the incorporation of a general
anisotropic scattering capability and the use of Fortran IV programming language. DTF-IV differed
in other respects: an up-scatter scaling procedure was added to accelerate and improve convergence
in problems with scattering from low energies to high energies, an optional point-wise convergence
test was incorporated, and a neutron conserving correction routine was introduced to prevent negative
fluxes. DTF-INDIA is a new version of CCC-42/DTF-IV.

**2. CONTRIBUTOR**

Reactor Research Centre, Kalpakkam Tamil Nadu, India.

**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.

This version of DTF was modified to accept a larger number of energy groups and handle special
cross sections preparation routines for deep penetration problems. Inhomogeneous and anisotropy
boundary source problems can be accommodated.

**5. METHOD OF SOLUTION**

DTF-INDIA 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, and a neutron conserving negative flux correction routine is used.

**6. RESTRICTIONS OR LIMITATIONS**

Only direct transport calculations can be done.

**7. TYPICAL RUNNING TIME**

A 100 group, 215 mesh, source calculation in a nonmultiplying medium requires 12.5 minutes for
15 iterations on an IBM 370/155 computer.

**8. COMPUTER HARDWARE REQUIREMENTS**

DTF-INDIA is operable on the IBM 360/370 computers. It requires 768 Kbytes of computer
memory.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCES**

K. D. Lathrop, "DTF-IV, a Fortran-IV Program for Solving the Multigroup Transport Equation with Anisotropic Scattering," LA-3373 (November 1965).

K. D. Lathrop, "GAMLEG - A Fortran Code to Produce Multigroup Cross Sections for Photon Transport Calculations," LA-3267 (April 1965).

Bengt G. Carlson, William J. Worlton, Walter Guber, and Martin Shapiro, "DTF Users Manual," UNC Phys/Math-3321, Vol. I and II (November 1963).

A. K. Jena, "DTF (Modified)," FRG/01150/RP-218 (February 1982).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

May 1984.

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