Application of the pulsed-eddy-current techniques for the inspection of the austenitic cladding in a thermal shock loaded nozzle of a pressure vessel

A pulsed-eddy-current test system was prepared for the nondestructive inspection of a thermal shock loaded nozzle of a pressure vessel. The computer-aided system used coil systems of several sizes to determine the depth of open-surface cracks. The calibration characteristics are stored within the memory of the computer to provide numerical signal evaluation. A scanning device was constructed to move the probes on to the nozzle surface. Signal acquisition and evaluation was controlled by means of a set of program modules. The in situ inspection procedures included a preliminary signal evaluation. The crack determination was influenced by a quantity of parameters as probe lift-off, super-position of a signals, limited resolution of probes and conducting connections within the cracks