The internal components and structures of boiler water reactors (BWRs)usually suffer the problem of intergranular stress corrosion cracking(IGSCC). Core shroud is one of these structures. Many BWR nuclear powerplants have reported the finding of IGSCCs around heat affected zone (HAZ)of core shroud weldments. In order to assure the integrity of the internalcomponents of reactors, in-vessel visual inspection (IVVI) is performedduring each outage of a reactor unit. Most IGSCCs were discovered initiallyby IVVI, and then inspected by automatic ultrasonic testing (AUT) system toconfirm the length and measure the depth of the cracks. In this project, anOD tracker was built for the scanning of ultrasonic testing. A weld testpiece with surface cracks near HAZ was mounted on a core shroud mock-up.These cracks were implanted thermal fatigue cracks, which were used tosimulate IGSCCs. The self-developed ultrasonic testing software was used tocontrol scanner, acquire data, display and analyze inspected images. Theobtained inspection results were satisfied.
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