ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ТЕПЛОМАССОПЕРЕНОСА В ПАРОГЕНЕРАТОРЕ РЕАКТОРНОЙ УСТАНОВКИ ТИПА БРЕСТ ПРИ ВОЗНИКНОВЕНИИ КРИСТАЛЛИЗАЦИИ СВИНЦОВОГО ТЕПЛОНОСИТЕЛЯ

Abstract

The method of numerical simulation has been developed describing non-stationary heat and mass transfer and thermal conductivity in a steam generator with liquid metal coolant when there is a crystallization process. The method takes into account the differences of the process depending on the condition of the contact surfaces. On its basis the dynamics of solid phase formation in a lead-coolant of reactor plant BREST type during the accident with the steam generator steam line depressurization has been studied. The calculations are carried out with using of the RASPLAV software complex, which allows modeling the interconnected dynamics of thermal-hydraulic processes in the first and second circuits in terms of the one-dimensional equilibrium approximation. It is shown that at failure of feed water lock-regulatory armature there is a full closure of flow section of the emergency steam generator first circuit by solid phase. Depending on the condition of the protective oxide layer of the heat exchange surface the solidification of lead coolant takes place either on the heat exchanger tubes or in the lower part of the steam generator reservoir. In both cases, there is a threat of cessation of circulation in the emergency loop. A brief description of the mathematical model of the steam generator and the reactor plant circuit as a whole is given. A one-dimensional description of heat and mass transfer is used. A thermodynamic equilibrium of the phases at the boundary of phase transfer is postulated. The test results of the programmed numerical model are given. The calculation of the high pressure pipeline rupture is tested by comparison with the experimental data. The calculation of the solid layer formation dynamics on the surface of heat exchange tubes is tested by comparing the numerical solution with the analytical solution of the Stefan problem. The results of this research can be used for design of reactors with a lead coolant.Keywords: Stefan problem, stop valve, mathematical model, steam generator, reactor plant, lead coolant, surface wettability, mixing feedwater heater, crystallization process, phase transfer.