b'2 is mostly -U while zone 3 has aof the individual phases, fission gasFigure 3. Thermal conductivity as a gradient of U and U-Zr phases. trapped in the bubbles (here it isfunction of radial location for irradiated Xenon) and a shape factor describingU-10 wt% Zr. Bulk fresh thermal Thermal conductivity as a functionconductivity from LFA (dashed line), of radial location is presented forthe sphericity of the pores. Thislocal TCM conductivity, fresh (open the irradiated U-Zr in Figure 3factor describes pores from perfectlytriangles), local irradiated thermal spherical to completely randomconductivity calculated from TCM comparing the values for the bulkshaped. It is shown that the localdiffusivity (solid triangles), and and local fresh material with theeffective thermal conductivity models calculated thermal conductivitythermal conductivity of the irradi- with spherical (open circles) and from the local TCM measurements.ated U-Zr based solely on volumerandom (stars) pores are comparedThe local calculated thermalfraction of phases is approximately conductivity comes from the values62-74% lower than the fresh material. used in Equation 1. A modifiedWhen accounting for the volume Maxwell-Eucken / EMT equationand shape of the porosity, the local was used to calculate effectivethermal conductivity decreases again.thermal conductivity, keff, that utilizes the thermal conductivities 2022|AFC ACCOMPLISHMENTS 125'