铅冷快堆蒸汽发生器传热管破裂事故下 的气泡迁移特性研究

The steam generator tube rupture (SGTR) accident represents a design basis accident for lead-cooled fast reactors. Under SGTR conditions, high-pressure water from the secondary circuit comes into direct contact with high-temperature molten lead in the primary circuit, resulting in intense interactions. The generated steam bubbles may be entrained into the active core region, posing a significant threat to reactor safety. This study investigates the bubble migration characteristics following such an accident in the European lead-cooled system (ELSY). A 1/8 geometric model of the ELSY primary cooling system was established using Ansys Fluent. Steadystate simulations of the primary circuit were first conducted to determine temperature and velocity fields. Subsequently, the Eulerian-Lagrangian method was employed to track bubble positions and trajectories under accident scenarios. The results indicate that the rupture location, bubble diameter, and coolant flow rate significantly influence bubble migration behavior in the primary circuit. Notably, bubbles with a diameter exceeding 0.42 mm were observed to escape directly from the upper surface of the steam generator. Moreover, a 10% reduction in coolant flow rate decreases the average minimum diameter for direct escape by approximately 0.2 mm.