Variational nodal transport methods with anisotropic scattering

The variational nodal method is generalized to treat within-group and group-to-group anisotropic scattering in two- and three-dimensional eigenvalue and fixed source problems. The resulting formalism is implemented as the VARIational Anisotropic Nodal Transport code (VARIANT) within the shell of the Argonne National Laboratory production code DIF3D. The code is applied to a series of Cartesian and hexagonal geometry model problems and the accuracy of the results compared to those from TWODANT and TWOHEX and to the Monte Carlo code VIM, respectively, in two and three dimensions. VARIANT is then applied to multigroup hexagonal representations of the Experimental Breeder Reactor II, and results are obtained for three-dimensional eigenvalue and for two-dimensional neutron-gamma heating problems.