Ultrasonic measurement of zirconium tubes used in channel-type nuclear reactors

Abstract An ultrasonic technique for the determination of the inner and outer diameters and wall thickness of zirconium tubes used in channel-type nuclear reactors has been developed. The method is based on the time-of-flight technique of ultrasonic waves reflected by the front and back walls of the tube. The measurements are performed around the circumference and along the axis of the tubes. The influence of eccentricity of the measuring probe is studied both theoretically and experimentally. It is shown that the absolute measurement error is less than 100 μtm for the diameters and 50 μm for the wall thickness. In situ tests carried out at the Ignalina state nuclear power plan:, Lithuania, proved the good performance of the system in a harsh environment.