Novel thermo-mechanical testing method of nuclear fuel cladding at elevated temperature

Abstract

Ceramic composites are being developed as the next generation accident tolerant fuel cladding for light water reactors. In this study, we report a novel method to evaluate thermo-mechanical robustness of ceramic nuclear fuel cladding tube under simulated accident conditions. A ceramic surrogate core is used as the "pressurizing media" inside the cladding tube. To mimic accident condition, the surrogate core is electrically heated up to 1,200°C to create a temperature gradient; stress in the cladding tube is generated by the mechanical interference of the surrogate core and the cladding tube. In order to apply digital image correlation (DIC) technique for surface strain measurement, a method to produce temperature-resistance speckle pattern was developed. By using a narrow bandpass filter and a LED source, stable reflective images of speckle pattern was achieved from room temperature up to over 1,000°C. This enabled the first successful full field strain mapping of nuclear fuel cladding at high temperature using 3D DIC technique. The surface strain distribution as well as the temperature data obtained can be used to validate numerical simulation models of nuclear fuel cladding. © The Society for Experimental Mechanics Inc. 2014.