Flaw detection and flaw size determination in electron-beam welded copper vessels using PA-SAFT

Spent fuel rods from Finnish nuclear power plants are to be permanently disposed in copper vessels in which electron beam weld seams are to provide a secure closure between the tubular part and the cover. Extensive measurements were performed on reference errors and natural weld flaws using a phased-array ultrasonic testing system. The evaluation can be done by conventional means. HF-A images were nonetheless stored to permit SAFT reconstruction. This makes it possible to generate SAFT images with correct location of echo sources, thus greatly facilitating the evaluation. Due to the fuel cells' cylindrical geometry substantial time can be saved by using polar coordinates in the SAFT algorithm. Moreover this directly supplies the data for the developed view (depth and angles). The article contains PowerPoint slides.