Acceleration method for nodal equation of diffusion equation in x-y geometry derived by finite fourier transformation

It was found that the convergence rate of the alternating direction implicit method for the nodal equation for the diffusion equation in x-y geometry derived by the finite Fourier transformation became slow as the absorption cross section decreases. This difficulty was found to be removed by eliminating the leakage term from the equation. An acceleration method and a method to obtain an optimum acceleration factor were developed for the iteration method to solve this equation. (author)