Crack detection and sizing technique by ultrasonic and electromagnetic methods

Improvements in defect detection and sizing capabilities for nan-destructiv e inspection techniques have been required in order to ensure the reliable operation and life extension of nuclear power plants. For the volumetric in spection, the phased array UT technique has superior capabilities for beam steering and focusing to objective regions, and real-time B-scan imaging wi thout mechanical scanning. In contrast to the conventional UT method, high- speed inspection is realized by the unique feature of the phased array tech nique. A 256-channel array system has developed for the inspection of weldm ent of BWR internal components such as core shrouds. The TOFD crack sizing technique also can be applied using this system. For the surface inspection , potential drop techniques and eddy current techniques have been improved, which combined the theoretical analysis. These techniques have the crack s izing capability for surface breaking cracks to which UT method is difficul t to apply. This paper provides the recent progress of these phased array a nd electromagnetic inspection techniques. (C) 2001 Elsevier Science B.V. Al l rights reserved.