Study on quantitative eddy current array detection technology of cracks at free segment in heat transfer tubes of nuclear power plants

Heat transfer tube as a nuclear power plant nuclear island part of the first and second loop of the border, plays a very important barrier role. At this stage, eddy current array (ECA) only serves as a qualitative inspection method of the transition of the expansion tube part of the heat transfer tube. However, with improvement of the dimensional requirements to understand defects information located at heat transfer tubes for nuclear power plants (NPP), qualitative inspection can no longer meet the requirements. In this paper, comparison of the signal amplitude between the peak and the trough of 360 degree sense area of X-probe coils, the accuracy of unilateral signal amplitude of crack located at free segment of the tube is studied and the quantitative error distribution was given when the ECA probe inserted into the tube at random position.