Development of a Fretting Wear Evaluation Method in the Nuclear Fuel Fretting by using a Wear Scar Shape

In order to evaluate the effects of a variation of a supporting springs' shape on the wear behavior of a nuclear fuel rod, sliding wear tests have been performed in room temperature air and water. The objective of the tests is to quantitatively evaluate the relationship between a worn area and a wear volume, and the formation behavior of a worn area with a variation of the slip amplitudes, applied normal loads and supporting spring shapes. The results indicated that the variation behavior of the volume and the wear scar size was influenced by the contact shape between the springs and the fuel rods. Also, it was found to be possible to evaluate a critical ratio (T(c)) for each spring shape and test condition when the T was defined as the ratio of an applied normal load (L(n)) to a wear scar size (A(t)). Below this T(c), the wear volume was rapidly increased and the T(c) was determined by a variation of the A(t) under the same applied normal load condition. This result enables us to evaluate a wear resistant spring shape by using an analysis of a wear scar after wear tests have been completed. Based on the above results, the relationship between A(t) and a worn area (A(w)), a wear mechanism and an evaluation method for a wear resistance were discussed.