COATED CLADDING BEHAVIOR DURING HIGH-TEMPERATURE TRANSIENTS

Abstract

The concept of accident-tolerant fuels has been proposed and widely investigated over the past decade. The contribution is focused on one of the near-term approaches - the modification of the surface of existing Zr-alloy claddings by protective coatings. The studied specimens are based on Zr-1%Nb substrate with chromium coating, multicomponent chromium nitride and chromium coating and multi-layer chromium nitride/chromium coating deposited by a physical vapor deposition process. Thermomechanical tests were designed to understand the cladding deformation and the burst conditions during the LOCA phenomena. Presented results show both the positive and the negative effect of coating on cladding behavior. All coatings exhibited a reduction of ballooning size and prolongation of time to burst. On the contrary, coating can be connected with larger opening size after burst, higher hydrogen content and deterioration of the local mechanical properties.