Measurement of temperature distribution and estimation of interfacial heat flux profiles during the interaction of different molten metals with ferrosiliceous concrete

The necessity of understanding the interaction of molten corium with the sacrificial concrete layer surrounding the nuclear reactors has been the motivation to perform MCCI experiments. Materials (zinc, aluminium and stainless steel) which have different melting temperatures and thermal properties are chosen and the experimental investigations are carried out by pouring molten metals in well-defined cavities of concrete test sections to study the ablation and thermal behaviour of the concrete. Coarse and fine aggregates of hematite are added to the cement to attain the required mechanical and thermal properties and provide better radiation shielding. The transient interaction of the molten metal with the concrete is measured using thermocouples. The measured subsurface temperatures are subsequently used to estimate the interfacial heat flux profiles by solving an inverse heat conduction problem using the sequential function specification method. The peak temperatures measured and peak heat flux values estimated in concrete samples interacted with zinc, aluminium and stainless steel are around 85 °C and 35 kW/m², 105 °C and 58 kW/m², and 468 °C and 65 kW/m², respectively. There is no ablation during the interaction of zinc and aluminium with the concrete test sections. Though the melting temperature of stainless steel (1450 °C) is higher than the ablation temperature of the concrete (around 1200 °C), concrete did not undergo significant ablation due to the higher density and the strength offered by the addition of hematite aggregates. The results presented in the current study are accurate within the time period where the semi-infinite model is valid.