Eigenvalues Calculation Algorithms for -modes Determination. Parallelization Approach

In this paper, we review two methods to obtain the A-modes of a nuclear reactor, Subspace Iteration method and Arnoldiʹs method, which are popular methods to solve the partial eigenvalue problem for a given matrix. In the developed application for the neutron diffusion equation we include improved acceleration techniques for both methods. Also, we propose two parallelization approaches for these methods, a coarse grain parallelization and a fine grain one. We have tested the developed algorithms with two realistic problems, focusing on the efficiency of the methods according to the CPU times