Experimental investigations and inverse heat transfer analysis to study heat transfer and ablation behaviour of concrete exposed to oxyacetylene flame

The phenomenon of ablation occurring in sacrificial concrete surrounding the nuclear reactor is studied by conducting experiments with oxyacetylene welding. The oxidizing flame produced from the oxyacetylene welding is a potential source of high heat flux and temperature exposed to the ferrosiliceous concrete (contains hematite aggregates) and ordinary concrete (without hematite aggregates). The ablation caused by the high-intensity oxidizing flame is observed to be highly non-uniform. The maximum temperature rise, ablation depths and overall mass loss in ordinary concrete are observed to be higher compared to the ferrosiliceous concrete. The presence of hematite in ferrosiliceous concrete has reduced the heat diffusion, ablation depth and mass of ablated material inside the concrete and hence exhibited better ablation characteristics. A semi-infinite heat transfer model ignoring the effects of chemical reactions are formulated and estimated the approximate interfacial heat flux profiles develop at the interface between the flame and concrete. The outcomes of the study conclude that the ferrosiliceous concrete can withstand the high heat fluxes of the oxidizing flame, and hence, it will withstand the adverse scenario of the interaction of molten corium with concrete walls occurs during the failure of nuclear reactors.