Study on Bubble Migration Characteristics in a Lead-Cooled Fast Reactor After Steam Generator Tube Rupture Accident

Abstract In this paper, the bubble migration characteristics of LFR after SGTR accidents are investigated based on the DPM. Firstly, the geometric and mesh models of the primary coolant system of the LFR are established, and the drag coefficient model of bubbles in the DPM is validated based on the bubble terminal velocities. Secondly, steady-state simulation of the primary coolant system of the LFR are performed to determine the temperature and velocity fields. Thirdly, the migration characteristics of the single bubble released from different positions of the SG are investigated, and the results show that bubbles on the horizontal plane at the window position were more easily entrained away from the window side, while those on the horizontal plane below the window were more easily entrained near the window side. Finally, the bubble groups with different diameters and different positions are studied. Bubbles larger than 0.3 mm leaking at any position of the SG cannot be entrained into the core, and bubbles larger than 0.45 mm will escape directly. Additionally, the higher the location of the rupture the lower the probability of bubbles entering the core.