An approach for stringent quality assurance of steam generator tubes

摘要

For detection of localised defects in ultrasonically acceptable wall thickness variation regions in 2.3 nan-thick ferromagnetic steam generator tubes, a two-frequency eddy current approach is proposed. The ultrasonic thickness data of a few defect-free tubes is utilised for optimisation of the two-frequency mixing parameters. The approach is validated by detecting a reference standard hole of 1.2 mm diameter in wall thickness variation regions. With suitable thresholds, this approach has been successfully implemented in production-line for meeting the stringent quality assurance needs of steam generator tubes during manufacturing stages.