A comparison of the lumped and consistent source treatments in 3-D finite-element diffusion calculations

This investigation concentrates on the solution of 3-D multigroup neutron diffusion equations by the finite-element method using two different source treatments. Both the lumped source treatment and the consistent source treatments are implemented in developed computer programs, which use bilinear finite elements. A comparison of the lumped and consistent source treatments with analytical results shows that convergence is obtained with both source treatments. Nevertheless, consistent source results seem to be more accurate than lumped source results. Similar behavior is observed when calculations are done for a benchmark problem, for which the results of mesh-edged, mesh-centered finite-difference and flux synthesis are available. (author)