경수로 원전연료용 지르칼로이 지지격자체의 성능 및 용접품질 분석

Performance and Welding Quality Analysis for the Zircaloy Spacer Grid Assembly of PWR Fuel

A spacer grid assembly, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assembly for pressurized water reactors(PWRs). The spacer grid assembly is structurally required to have enough buckling strength under various kinds of lateral loads acting on the nuclear fuel assembly so as to keep the nuclear fuel assembly straight. And also, the spacer grid assembly is hydraulically required to have less hydraulic resistance of coolant. To meet this requirement, it is necessary to weld the welding parts carefully and precisely. In this study, weld qualities such as, weld bead size and spatter manufactured by various welders were compared and analyzed. And performance parameters such as impact strength of spacer grid and hydraulic resistance of coolant were also compared and analyzed. Comparison results show that the weld qualities could be improved by selecting the optimal welding condition and also improving the welding technique.