A symmetrized quasidiffusion method for solving transport problems in multidimensional geometries

In multidimensional geometries, the Quasidiffusion scheme requires that a non-selfadjoint diffusion problem be solved within each iteration. The non-selfadjointness of the diffusion problem causes difficulties in its discretization and in the solution procedures for solving the discretized equations. We show that this non-selfadjoint problem can be replaced by two selfadjoint problems, both of which can be accurately discretized using a variational principle, and both of which can be solved efficiently using standard techniques. (orig.)