Systematic experimental investigation on the characteristics of molten copper fragmentation in water

摘要: During severe accidents in pressurized water reactors, thermal and hydraulic interactions play a crucial role in the Fuel-Coolant Interactions (FCI). Motivated to benefit the understanding on the fragmentation behavior of molten metallic fuel in water, in this study a series of simulated experiments is systematically conducted by injecting molten copper into a water pool. By adjusting parameters such as melt temperature, water temperature, melt penetration velocity, and water depth, the effects of these parameters on the fragmentation behavior of molten copper jet are investigated. It is found that water temperature determines the boiling mode during FCI, and at higher water temperatures, molten copper may not solidify and instead reach the bottom of the vessel in liquid form. When the melt temperature rises, the fragmentation process becomes less thorough, leading to an increase in the mass mean debris diameter. Higher penetration velocity of the molten metal results in smaller particles. A water depth greater than 70 cm has little effect on the fragmentation behavior. Weber number theory performs better in predicting the mass mean diameter of debris formed, comparing with the Rayleigh-Taylor and Kelvin-Helmholtz instability fragmentation theories.