SIMULATION OF THERMOKINETIC PROCESSES IN CRUCIBLE TRAPS OF HIGH-TEMPERATURE MELT OF CORIUM IN SEVERE ACCIDENTS OF REACTORS AT NUCLEAR POWER PLANT

Abstract

The two-stage model of changing the thermal and phase state of the active zone melt in the cooled subreactor crucible trap when interacting with the sacrificial material and when crystallizing the diluted corium after the gravitational inversion of its oxide and metal components is presented. The simulation is based on the generalized formulation of Stefan's task with the loose boundaries of the phase section, taking into account the residual radioactive heat output of the corium, the thermal effects of melting the sacrificial material and the chemical reactions of the restoration of its oxides in the oxidation of the under-oxidified elements of the melt, the heat transfer of natural convection in the melt, the heat transmission of cooling water through the walls of the hull and thermal radiation in the internal space. The results of the end-to-end calculation of the COMSOL Multiphysics package show that the thermokinetic processes examined generally reduce the temperature and density of the corium, reduce heat flows on the trap body, minimize the release of hydrogen and radioactive fission products with their retention in a controlled thermal and phase state until full crystallization.

Keywords

• melt active zone
• subreactor crucible trap
• sacrificial material
• thermal state