Transmission Electron Microscopy based Characterization of a U-20Pu-10Zr Fuel Irradiated in Experimental Breeder Reactor-II

Abstract

U-Pu-Zr metallic fuels are important fuel candidates for future advanced and/or test reactors. To better understand the fuel performance and guide future fuel design, a U-20Pu-10Zr (in weight) metallic fuel irradiated in the Experimental Breeder Reactor-Ⅱ was revisited using advanced electron microscopies. This fuel cross section was irradiated to a burnup of 6.15 % at a cladding temperature of ∼500°C. Several transmission electron microscopy samples were extracted from different but representative radial locations of the fuel cross section using focused ion beam technique. Phase identification and chemical analysis with sub-micron spatial resolution were carried out using a scanning transmission electron microscopy. Multiple phenomena that are critical to fuel performance, such as Zr redistribution, were revealed in an unpreceded highly detailed manner. An improved understanding of fuel reconstruction in U-Pu-Zr metallic fuel under reactor irradiation is provided.