Experience with a new ultrasonic inspection system for non-destructive examination of canning tubes

The Risoe/HV Tube Inspection System is designed for fast automatic inspection of precision tubes for dimensions and defects. The system is built around a rotating water chamber with eight ultrasonic transducers. The tube handling and evaluation of the results could be made in different ways by various combination of modules in the system. By standard inspection of canning tubes for nuclear fuel, the inspection speed is 6m of tube per minute with the chamber rotating 3000rev/min; tubes are fed through the system without rotation, and, owing to the conical tube guide used, very gentle treatment of the tubes is assured. Evaluation and development work on this system has been performed during the last three years and has been based on practical experience with tube inspection. The accuracy and stability of the system has been improved by innovation in both the mechanical system (especially water circulation and temperature regulation) and the electronic modules (ultrasonic equipment). Also the ultrasonic transducers have been studied and changed. The calibration procedure has been simplified and improved both for dimensions and defects. The influence of the different improvements on stability and accuracy during actual tube inspection has been ascertained by repeated inspection of the same 17 tubes. The results from these inspections indicate an accuracy and stability of less than 5μm on dimension measurements during actual tube examinations. (author)