Wielandt Iteration as Applied to the Nodal Expansion Method

An implementation of Wielandt’s method of eigenvalue shifting to accelerate the convergence of nodal expansion method (NEM) reactor calculations is presented. This particular formulation of the method greatly decreases the number of source iterations required for a particular degree of convergence while retaining most of the efficiency of a groupwise solution procedure for the inner iterations. The nature of the NEM equations causes Wielandt’s method to behave somewhat differently than when it is applied to the finite difference equations. Results are presented for well-known two- and three-dimensional benchmark problems.