Modelling the ultrasonic inspection of smooth and rough planar defects [and nuclear power plant application]

A suite of computer codes has been developed for the theoretical modelling of ultrasonic inspection in ferritic steel. The models predict the echo amplitudes from postulated planar defects in direct pulse-echo, "corner effect", tandem or TOFD configurations. In general the defects are assumed to be smooth, but for direct pulse-echo a model is also available for rough defects. The models are mostly used to establish the capability of a proposed inspection procedure to detect hypothetical defects which could be of structural concern. They have an important role in providing evidence for technical justifications when qualifying inspections using the methodology described by ENIQ (the European Network for Inspection Qualification). This paper will describe the range of models currently available in the authors' companies, concentrating on recent developments. In particular the important issue of the validation of models against experiment will be discussed. Finally, some typical examples of use of the models will be briefly described.