Tip-over Analysis Of 14OFA PWR Fuel Assembly

This objective of this work was to propose a methodology for precise simulation of fuel rod behavior in 14OFA during tip-over impact situation. In order to the satisfy the objective, we tried to analyze tip-over of fuel assembly by comparing cases of spot welding and of line welding at inner connection of mid-spacer grid. The Multi Point Constraints (MPC) method was used to represent spot welding and the simulation results in ABAQUS were evaluated according to MPC options (tie and beam). Compared to the case in which connections are perfectly bonded, in the case in which spot-welding was performed at both ends of the inner connection at the mid-grid spacer, locally large deformation occurs at tip-over impact. It was found that this affected the bowing of the fuel assembly and the maximum load on the fuel rod also decreased. Based on the tip-over analysis results, we analyzed the influence of the interaction between the spacer grid and the cladding tube. The detailed analysis methodology will be used to evaluate the integrity of fuel rods when the spent nuclear fuel will be handled in future.