Evaluation of different ultrasonic probe concepts for the inspection of claddings

Stainless steel claddings in the interior of reactor pressure vessels and other primary circuit components exert a strong influence on the ultrasonic inspection of the entire component as well as on the cladded area. Since the introduction of ultrasonic inspection for inservice inspections during the 1970s, the cladding influence has been investigated many times. Interest has increased in ultrasonic inspection of the cladding and the area close to it for studying certain corrosion aspects and possible cracks or crack growth. This paper concentrates on evaluating the performance of specific ultrasonic probes frequently used for typical crack type indications in the cladding, especially for underclad cracks. All probes of interest here are probes with inclined incidence of the excited beams. Measurement of the cladding layer thickness and the tests for lack of fusion between the base material and the cladding were not considered.