Abstract
A comparative analysis is made of calculations of a loss-of-coolant accident in a 1500 MW(t) fast reactor. The COREMELT code with different neutron-physical modules RADAR3D and RAKAR2D and the same thermohydraulic module COREMELT are used. The computational results are used as a basis for comparing the self-protection of a reactor with a sodium cavity at the top of the core for the case of a serious accident with coolant boiling. The effect of the diffusion and transport modules of the spatial neutron-physics models on the calculation is analyzed.