Research on the Natural Circulation Ability of Lead-Bismuth-Steamwater Direct Contact Multiphase Flow

Abstract Pb-Bi-cooled direct contact boiling water fast reactor (PBWFR) uses a large amount of steam generated by the direct contact heat exchange between liquid metal and water to drive the natural circulation flow of lead bismuth (Pb-Bi) alloy in the primary circuit. To explore the natural circulation flow characteristics of Pb-Bi-water-steam multiphase flow is of great significance for improving the natural circulation ability of Pb-Bi. This paper establishes a one-dimensional theoretical analysis program and numerical simulation calculation program for the PBWFR system, It’s the law of the natural circulation ability of Pb-Bi was obtained with the change of core power, ascent channel height, water injection subcooling degree and so on. At the same time, the transient process of direct contact between Pb-Bi and water at high temperature and high pressure was simulated by numerical simulation program. The key parameters such as temperature, velocity and void fraction of Pb-Bi multiphase flow in the ascending channel were obtained. The research in this paper lays a theoretical foundation for in-depth exploration of the natural circulation mechanism of Pb-Bi, which is helpful for the optimal design of PBWFR reactors.