Preconditioning the Power Method for Reactor Calculations

Several preconditioning techniques were applied to the power method, in conjunction with a symmetric variational acceleration strategy, to facilitate solution of reactor problems. First, the drawbacks in an approximate inversion were corrected by fitting an error recovery term to the power method. Second, a variational extrapolation technique that does not require knowledge of the dominance ratio was introduced. Validation results are reported for the International Atomic Energy Agency two- and three-dimensional benchmarks and for a two-dimensional pressurized water reactor representation.