Development of a Modeling Approach to Describe Thermal Conductivity of Prototypic SiC-SiC tubes for LWR Fuel Cladding

Abstract

SiC/SiC composites are a promising material intended to be used as a fuel cladding for light water reactors. This material has exceptional steam oxidation resistance, outstanding high temperature strength, and small neutron cross sections. Thermal conductivity is one of the most important physical properties for modeling and assessment for the performance of SiC/SiC composite-cladded fuels. However, there is a significant lack of knowledge for thermal conductivity of tube materials because of the variability of thermal conductivity with the architecture and manufacturing quality of SiC-SiC composites, the challenge associated with measurement with small diameter tubes, and the complex nature of the effects of neutron irradiation on transport properties of composite materials. Development of a constitutive model of the composite thermal conductivity incorporating the effects of temperature, neutron irradiation, and potential matrix damages is essential toward a comprehensive performance modeling for the SiC-SiC composite-cladded fuels. As such, the current effort focuses on establishing a highfidelity thermal conductivity model for SiC-SiC composite cladding.