Inspection of the UO2 fuel for the prototype heavy water reactor 'FUGEN'

124 UO2 fuel assemblies for the prototype heavy water reactor ''FUGEN'' were fabricated by the Nuclear Fuel Industries, Ltd. (NFI). Following the inspection of UO2 pellets, fuel element and assembly parts made by the maker after completing their fabrication, PNC made the field inspection of the fabrication of UO2 fuel assemblies. The fabrication and inspection process diagram is illustrated, and the list of the parts subjected to the inspection and the inspection items are shown. In addition, check was made on the quality control and the transportation test of pellets. The total or sampling inspection was made on the parts as well as non-destructive examination. The actual inspection was conducted as follows: for example, 1) the visual inspection of UO2 pellets was conducted on the total number of pellets and the stack, after adjusting the pellet stack, and the inferior pellets were rejected, 2) the fuel element parts and fuel elements were examined by the total or sampling inspection, and all of the parts were found to be in accordance with the specification, 3) the fuel assembly parts were examined by the sampling inspection, and all of them were found to meet the specification. The sampling inspection was made as the visual and dimensional inspections on the fuel assemblies. For the dimensional inspection, measurement of the full length, spacer interval, pin to pin gap, straightness and distorsion was made, and 4) on the situation of the quality control from the raw materials for UO2 pellets, fuel element and assembly parts to the shipment as UO2 pellets, fuel elements and assemblies, check was made by the use of pertaining documents, photographs, and post-examination samples, etc. It was recognized that the quality control was carried out in the quality assurance program. (Nakai, Y.)