Development of automated ultrasonic testing machine for PHWR endclosure welds

PHWR fuel bundle essentially consists of a cluster of fuel elements whose ends are welded by endplates to form a bundle. Each fuel pin consists of loaded with sintered UO2 pellets and the tube ends are hermetically sealed by resistance welding. The end- cap weld of the fuel element is the most critical operation during the fabrication of PHWR fuel bundles. The weld has to maintain its integrity in the harsh reactor environment throughout its residence in the reactor. Any failure in the weld will lead to leakage of fission product in to the coolant circuit. In order to ensure the end-cap weld integrity, stringent quality control procedures are followed. The quality assurance procedure involves qualification of men and machines, while inspection techniques involve both destructive and non-destructive testing, metallographic weld evaluation is carried out on sampling basis. Therefore the paper brings out the details of design and performance of the new semi automatic computerized ultrasonic testing system for PHWR fuel elements. The paper brings out the details of design and performance of the new semi automatic computerized ultrasonic testing system for PHWR fuel elements