Model of a stationary thermal detonation wave in the “liquid lead – water” system for safety analysis of NPP with the reactor BREST-OD-300 during heat exchanger tube break accident

Abstract

Abstract This paper presents a mathematical model of a stationary wave of thermal detonation in the “liquid lead - water” system, which can occur after the rupture of a steam generator tube of the reactor BREST-OD-300. The model is based on the mechanics of multiphase fluid flows. The system under study includes a continuous phase of liquid lead, in which drops of water surrounded by a steam film are dispersed. Heat exchange between high-temperature molten lead and water drops is carried out in the film boiling mode. A shock wave propagating in this multiphase system causes all phases in motion. Due to the significant difference in density between liquid lead and water, a difference in velocities arises between dispersed water drops and liquid lead, which cause the fragmentation of water droplets. The shock wave velocity and amplitude are determined by constructing the shock adiabat and the Hugoniot adiabat for the parameters of the studied multiphase mixture. To describe the fragmentation of water droplets, heat transfer between phases, and interfacial friction, the empirical correlations of the thermal detonation theory are used. The obtained numerical solutions describe the distributions of parameters in the zone of melt – water interaction.