Fretting can be defined as the oscillatory motion with very small amplitudes, which usually occur between two contacting surfaces. Fretting wear is the removal of material from contacting surfaces through fretting action. This fretting wear, which occurs between cladding tubes of nuclear fuel rod and grids, causes in damages the cladding tubes by flow induced vibration in a nuclear reactor. In this paper the fretting wear tests were performed with two types of cladding tubes and three types of supporting grids in water. Fretting wear tests were done using various applied loads. From the results of fretting tests, the wear amounts of tube materials can be predictable by obtaining the wear coefficient using the work rate model. Depending on various normal load, tube materials, and supporting grid shapes, distinctively different wear scar of fretting and stick-slip mechanism can occur.