Within the framework of large-scale MOCKA (KIT, Germany) experiments, a series of experiments have been performed to study the interaction of a simulant oxide (Al2O3, ZrO2, CaO) and metal melt (Fe) in a stratified configuration. To allow for a longer-term interaction, additional heating was provided by alternating additions of thermite and Zr metal to the melt. Since the heat generated by the thermite reaction and the exothermal oxidation reaction of Zr is mainly deposited in the oxide phase, prototypic heating of both melt phases is achieved. This allows the investigation of concrete erosion by metal melt as well as by the oxide which was not possible in all former experiments.
Current tests in the MOCKA (KIT, Germany) program are focused on assessing the influence of concrete reinforcement (rebars) on the cavity erosion behaviour using a simulant oxide-iron melt in a stratified configuration. The experiments are performed in siliceous concrete crucibles with an inner diameter of 25 cm containing 12 wt.% reinforcement. In these experiments, the overall downward erosion by the metal melt was of the same order as the sideward one. In addition, the lateral erosion in the overlaid oxide melt region was about the same as in the metal melt region. The former experiments (BETA, COMET-L) and MOCKA tests on siliceous concrete without reinforcement have produced results with pronounced downward erosion by the metal phase. This pronounced downward erosion of the siliceous concrete without rebars seems to be inherent for melts containing a significant fraction of iron.