BETA experiments in verification of the Wechsl code: experimental results on the melt-concrete interaction

Abstract The BETA experiments are conducted to investigate the melt-concrete interaction in a large-scale melt facility using internally heated simulated core melts. The experimental findings are extrapolated to reactor accident conditions by means of computer codes verified experimentally. The experiments cover a wide range of temperatures and power rates typical of accident conditions. In high-temperature melts, fast downward erosion determines the cavity shape and the very high downward heat transfer causes the temperature of the melt to drop rapidly, even with high internal heating. Crust formation at the interface between the melt and the concrete during the low-temperature interaction allows the gases evolved by the concrete to percolate through the melt, thus establishing an effective gas driven mode of heat transfer. Measurements of gases and aerosols are reported and discussed for silicate and limestone types of concrete.