2011:16 Modelling of ultrasonic testing of cracks in cladding

During the last two decades, SSM has supported research to develop a model for the non-destructive test situation based on ultrasonic technique. Such a model is important in many ways, for example to supplement and plan experimental studies and to perform parametric studies in qualification situation. Modeling can be a useful tool when the inspection system shall be technically justified. Many functions have been added to the model UTDefect and in this step propagation of ultrasound and signal responses from defect in the cladding of austenitic steel are studied.

Pipes and components in nuclear power plants are often equipped with a cladding material to prevent material degradation by the influence of media on the surface. This cladding material, often anisotropic, makes the ultrasonic examination more difficult. This project was set up to better understand the phenomena and model the propagation and defect scattering of the ultrasonic signal in this kind of material combination.

The report describes work that has been performed to model the scattering by cracks in a cladding in the full three-dimensional case. The cladding can be corrugated in the boundary between base material and cladding.

The results shows that the corrugated interface can have important and in some cases large effects on the signal response. The result depends crucially on the parameters chosen for the corrugation also the material properties can affect the results.