Method for Calculation of Fretting Wear of PWR Fuel Rod Cladding

Archard wear formula was used as the theoretical model for fretting wear of PWR fuel rod cladding, and the fretting wear volume between fuel rod cladding and grid would be predicted through this formula, where the significant physical quantities were wear coefficient, contact force between fuel rod and grid, and sliding distance. Wear coefficient was determined by experiment. Contact force between fuel rod and grid was a function varied with assembly burnup, which was determined by experiment or engineering empirical formula. The maximum vibration displacement for all modes would produce relative sliding if the displacement exceeded the threshold which was defined by grid dimple stiffness, contact force between fuel rod and grid, and friction between them, and the sliding distance could be estimated in an infinitesimal time increment. After the three physical quantities were determined, wear formula integral was implemented to obtain the fretting wear volume. According to the wear geometry of cylinder-plane contact, the relationship between wear volume and depth was derived theoretically, then the wear depth could be obtained from the wear volume. Finally comparing the wear depth to the criterion, it was validated that whether the fuel rod could satisfy the requirement on mechanism integrality.