Experimental study of ultrasound propagation at a liquid-solid composite interface for inspection of liquid-metal cooled nuclear reactors

The influence of unfilled cavities at a liquid-solid interface on ultrasound propagation is investigated. This kind of interface exists only when the surface is rough and the liquid is non-wetting. Normally incident compression waves are used. Possible modelling approaches are discussed, showing that no model is able to efficiently describe this kind of interface. We demonstrate that wave transmission drops dramatically. It is suggested that the incoming ultrasonic energy induces the growth and the coalescence of the vapour phase contained in the unfilled cavities under ultrasound field. A major result of this paper is to provide proof that difficult experiments in metal-liquid can be replaced by easier experiments in water. (authors)