DTF-4, 1-D Multigroup Time-Independent Boltzmann Equation, Slab, Cylindrical, Spherical Geometry, Sn-Method, Pl-Method

1 - Description of problem or function: 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. A complete energy-transfer scattering matrix is allowed for each Legendre component of the scattering cross section matrices. 2 - Method of solution: 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. Approximations and iterative cycles are described in detail in the DTF4 report. 3 - Restrictions on the complexity of the problem: The variable dimensioning capability of FORTRAN IV has been utilized so that any combination of number of groups, number of spatial intervals, size of angular quadrature, etc., can be used that will fit within the total core storage available to a user. The code itself requires about 8000 words, but it can be shortened by deleting certain subroutines which perform optional calculations