Solution of the principal spectral problem for a system of multigroup diffusion equations

Two new iterative methods (a block iteration method and a multigrid method) are proposed for solving the principal spectral problem for the system of multigroup diffusion equations describing the steady state of a nuclear reactor. The methods are described as implemented in a two-dimensional (R-Z) 26-group model of a BN-800 reactor. Some results illustrating the efficiency of the proposed algorithms and a comparison with the conventional source iteration method are presented.