Study on the effect of jet cross section shape on molten fuel fragmentation behavior with simulant experiments

Abstract

In this study, melt-jets with elliptical cross sections are employed with different melt temperature, water temperature, penetration velocity and water depth to explore the influence of the jet cross-sectional shape on melt-jet fragmentation behavior. When free fall distance is larger than 40 cm, the jet cross-sectional shape has no obvious influence on the fragmentation behavior in the current experimental conditions. When water temperature or melt temperature increases, the fragmentation becomes more complete with higher debris bed sphericity and smaller debris bed porosity. When melt penetration velocity is higher, smaller particles can be produced, but it has no obvious effect on debris bed porosity and sphericity. Water depth which is larger than 40 cm has no obvious effect on the fragmentation behavior. Weber number theory can be used to predict the mass median diameter of debris bed, and Stephan number (St) to predict the trend of debris bed porosity and sphericity. The jet breakup length model proposed by Epstein and Fauske (2001) is much better to predict jet breakup length.