Semi-Implicit Method for Calculation of the Non-Stationary Neutron-Physical Processes in Multigroup Diffusion Approximation in Two Dimensional Geometry

A non-stationary physical reactor model in two-dimensional geometry is considered. This model is based on solving the neutron transport equation in multigroup diffusion approximation taking into account delayed neutrons at each time step. The system of equations, corresponding to this problem, belongs to a class of 'stiff' systems. A semi-implicit algorithm, which is the alternating direction method with exponential transformation, is proposed in this paper to solve the system of this kind. Advantages of this method in comparison with the implicit successive over-relaxation method are investigated using test models.