SYN-3D, 2-D and 3-D Neutron Diffusion Static Eigenvalues, Single Channel Spatial Flux Synthesis

1 - Description of problem or function: SYN3D solves the direct and adjoint, diffusion theory, static eigenvalue equations in two and three dimensions. The geometries available are x-y, r-z, x-y-z and triangular-z. 2 - Method of solution: SYN3D uses single-channel spatial flux synthesis to calculate approximate solutions to the three- dimensional (or two-dimensional) diffusion theory difference equations. Synthesis expansion functions must be supplied by the user from two-dimensional (or one-dimensional) finite-difference calculations performed by some other code. SYN3D sets up the synthesis equations and solves them by power iteration with Wielandt acceleration. Each iteration is an exact inversion of the block-tridiagonal synthesis equations by forward-elimination, backward-substitution. 3 - Restrictions on the complexity of the problem: The only serious limitation is on the product of the number of groups and the maximum number of expansion functions used at any particular axial elevation