An ultrasonic inside-diameter (ID) control system was used during the final etching process for producing Zircaloy nuclear fuel cladding tubes. This results in establishing automatic inside-diameter control during etching with an automatic etching system.

In this system, the inside-diameter at the center point in the length of each tube is continuously measured with the ultrasonic inside-diameter measuring equipment during the etching process and the etching is automatically stopped by a signal from the control equipment when the inside-diameter reaches the target value.

This made the final etching process economical and suitable for large-scale production, having an equal or better level at the inside-diameter of tubes etched with this system than those made by a process controlled by an air-micrometer.