An Ultrasonic System for the Inspection of Components with Irregular Geometry Using a Flexible Phased Array Contact Transducer and Related Processing Algorithms

The primary and secondary cooling systems of French pressurized water reactor contain many welded components with complex geometry : elbows, welding without smooth profile, nozzles. In service inspections of such components performed with conventional ultrasonic (US) contact transducers present limited performances. First, variations in sensitivity, due to unmatched contact on depressions or irregular surface are observed, resulting in poor detection performances. In addition, the beam orientation transmitted through complex interfaces cannot be totally controlled, because of the disorientations suffered by the transducer during its displacement. As a result, the detected defect cannot be correctly characterized, in terms of localization, geometry, orientation and size. At last, the geometry of some components, for example nozzles, disturbs the displacement of the transducer, resulting in an uncovered scan area.