Large scale experiments on core-concrete interaction: BETA-experiments and WECHSL-code verification

The BETA experiments on melt-concrete interaction cover a wide range of temperatures and power rates typical for accident conditions. For a high temperature two component melt the very high downward heat transfer causes significant downward erosion combined with rapid drop of melt temperature. Crust formation at melt concrete interface during low temperature interaction allows the gases to percolate through the melt establishing an effective gas driven heat transfer mode. Gas and aerosol measurements are reported. The WECHSL computer code is being verified by the experiments to allow the final application to the reactor situation. It is proved both experimentally and theoretically that the long-term concrete erosion is governed by partly or completely solidified metal slugs and oxide melt pools with temperatures close to the solidification temperature of steel