Rethinking the Role of Pu in Metallic Fuel Behavior—How Does Pu Impact Constituent Redistribution and Thermal Properties?

We have recently demonstrated that Pu radial concentrations in irradiated U-Pu-Zr fuels do not remain constant across the fuel radius, which raises several important questions:

What role does Pu play in constituent redistribution?
Does Pu impact thermal properties of irradiated fuels?
How does local thermal conductivity change with burnup?

To answer these questions, we conducted a systematic analysis of U-19Pu-10Zr and U-10Zr fuels using electron microscopy techniques and mesoscale thermo-reflectance methods, and correlated structure and properties of metallic fuels as a function of radial location. We will focus on the behavior of several fuels, including U-20Pu-10Zr irradiated to burnups ranging from ultra-low (0.001 at.%) to high (11 at.%) and U-10Zr fuel irradiated to a burnup of ~11 at.%, and highlight how properties and constituent redistribution are impacted by burnup.