Testing the debris fretting phenomenon of new perspective materials under LWR conditions

Despite decades of advancements and research aimed at improving fuel’s physical properties, fretting damage to fuel cladding remains a significant challenge. This study outlines the findings of experiments conducted on Zr-1%Nb alloy coated with protective layers composed of chromium-aluminium (CrAl) compounds and other new perspective materials, such as FeCrAl and CrNi alloys, at the Research Centre Řež. The experiments included debris-fretting tests performed under LWR conditions (320 °C and 15 MPa) and microscopic evaluations of groove depths. The primary goals were: (1) to evaluate the debris-fretting resistance of uncoated Zr-1%Nb samples compared to Zr-1%Nb with coatings and new alloys, and (2) to investigate the potential effects of coatings and new materials on the durability of fuel cladding. The conducted experiments and studies confirmed the benefits of the wear resistance of the ATF types of claddings in comparison to the standard Zr-1%Nb cladding material. Various parameters, such as wire wear and the influence of mutual position of the samples, were considered during the testing to provide the most precise insight into the wear resistance of the tested samples.