Effect of contact misalignment on fretting wear behavior between fuel cladding and Zr-4 grid

Abstract

Cladding fuel rods supported in grids are important core components in pressurized water nuclear reactors. Small rod-to-grid misalignments can occur during the core manufacturing process. The presence of tilted contacts may promote fretting wear damage between claddings and grids by flow-induced vibrations (FIV). In this study, the influence of tilted contacts on the fretting wear between fuel rod cladding and a Zr-4 alloy grid, caused by deviations during assembly, was analyzed and discussed. A 3D finite element model was set up to obtain the stress state on the contact interface between the cladding and grid under different included angles. Results show that the wear morphology and profile presented evident dependence on the included angle. The change of the included angle between the cladding and grid changes the contact form of the two, leading to changes in the local stress and contact area in the interface. This process ultimately changes the thickness of the wear debris accumulation layer (WDL).