b'Thermal Conductivity Measurement of Fresh SiC CMCPrincipal Investigator: Cynthia AdkinsTeam Members/Collaborators: Tsvetoslav Pavlov, Zilong Hua, Ethan Hisle, Michael C. Marshall, Peng XuT his is a method develop- fuel rods behavior during normal ment project for thermaland off-normal reactor operating conductivity measurementconditions. This study focuses on the on an unfueled silicon carbidethermal conductivity of the cladding fiber, silicon carbide matrix (SiC- and Sn bonding layers of the total fuel SiC) composite cladding systemdesign at room temperature through where surrogate fuel material isthe melting temperature of Sn. It is Tin-bonded within the cladding.important to determine any effect This project scope focuses on ason thermal conductivity due to the fabricated material, however thepresence of Sn both solid and liquid data collected, and analysis methodsas well as the independent thermal used will be directly applicable toconductivity of the SiC-SiC composite the post-irradiated rodlets that arematerial, including the individual being irradiated in the Advancedcomponents of the composite. In this Test Reactor. The goal of this testingstudy the UO 2fuel rodlet is replaced is to capture important materialwith a surrogate material, molyb-properties and cladding compo- denum metal.nent performance data on rodletsPulse laser flash analysis (LFA) and provided by General Atomics Elec- modulated thermoreflectance using tromagnetic Systems (GA-EMS). Thea thermal conductivity microscope data collected will be used to inform(TCM) are used to measure the GA-EMS SiC-SiC cladding design. thermal diffusivity radially across Project Description: the cross-section of the SiC-SiC GA-EMS has put forth a SiC accidentcomposite alone and the SiC-SiC/Sn/tolerant fuel concept where a SiC-SiCMo surrogate fuel system, in both the composite cladding tube is used tobulk and micro scale, respectively. encapsulate UO 2rodlets that areThermal diffusivity is directly related bonded to the inside of the claddingto thermal conductivity, an impor-tube using liquid Sn. This fuel/clad- tant parameter for characterizing and ding design needs comprehensivemodeling heat transfer performance characterization of thermophysicalof materials. Further method devel-and mechanical properties beforeopment is needed to correct for the and after irradiation testing. Accuratecurvature of the cladding in the LFA thermo-mechanical property dataand the surface topography within is of paramount importance for fuelthe SiC-SiC composite. Likewise, for performance codes to predict thethe TCM method, further develop-62 2023|AFC ACCOMPLISHMENTS'