Radiative and Convective Heat Transfer in the Gas Cavity of VVER-1200 Melt Trap

Heat transfer in the gas cavity of the melt trap for the VVER-1200 core is studied. A model problem is solved numerically in a configuration where the cavity boundaries are close to that obtained after the formation of the melt pool. Heat transfer by radiation is calculated by three methods: in the approximation of a transparent medium taking account of the angular coefficients of radiation emission of sections of the cavity boundaries, by the DTRM method suitable for calculating radiation transfer in a medium with arbitrary optical density, and by the diffusion method in the Rosseland approximation. It is shown that the dominant mechanism is thermal radiation; the contribution of convection of the gas is relatively small. The influence of the choice of computational method on heat transfer in a gas cavity with different absorption is evaluated.