Evaluation of fretting damage of zircaloy cladding tubes

The work is part of the search for a technique to study the fretting properties of the cladding of fuel rods in nuclear reactors. The strategy is to compare the fretting scars of specimens tested in a near-full-scale, nonradioactive simulator (so called fuel assembly endurance test) with scars on specimens tested under well controlled conditions in the laboratory. By systematic variations of the laboratory resting parameters it has proved possible to achieve scars with the same type of damage characteristics as those from the fuel assembly endurance test. This makes it possible to estimate, by deduction, the parameters that cause fretting damage under actual sen,ice conditions in a reactor.