Characterization of U-Zr alloys for ultrahigh burn-up nuclear fuels

Abstract

Uranium-zirconium alloys are being investigated for use in ultrahigh burn-up, metallic inert matrix nuclear fuels (IMF). The IMF platform provides an opportunity to study the system components (fuel, metallic matrix, and cladding) separately prior to studying their interactions in the integrated fuel form. Characterization of these materials in the transmission electron microscope allows determination of the compositions, morphologies, and crystallography of the phases present at scales that cannot be accessed by other techniques, such as X-ray diffraction and optical microscopy. For example, it has proven difficult to detect the presence of the equilibrium, nonstoichiometric intermetallic δ phase in as-cast, low-Zr-content U-Zr alloys. Here it will be shown that the δ phase coexists with the equilibrium α phase as a fine-scale lamellar structure in an as-cast U-10 wt% Zr alloy. We will present characterization results from U-Zr alloys and discuss their potential use as actinide fuels in the IMF design.