ABSTRACT:
Active research is underway at Ispra to understand the fundamentals of the FCI process and to support modeling of this phenomenon. The KROTOS experiments focus on providing benchmark data to examine the effect of fuel-coolant initial conditions on explosion energetics. Recently, tests have been performed with molten alumina-water to examine the effect of fuel temperature on explosion energetics; i.e., KROTOS 38, 40, 42 with fuel temperatures from 2470 to 3070K with melt superheats of 150 to 750K with a mass of 1.5 kg into 34 kg of water at ambient conditions. Strong spontaneous explosions were observed in all the tests with peak pressures of 60 - 90 MPa and conversion ratios of 0.9 to 1.9% . The location and timing of the explosion varied notably with integral voids estimated to be 1-3% . The TEXAS FCI model was used to analyze these tests along with a new thermodynamic model. Both approaches predicted similar integral void fractions. Using the semi-empirical fuel fragmentation model previously developed and a newly developed model for a spontaneous trigger, good agreement was obtained in predicting the peak explosion pressures.