Microstructural and mechanical property characterization of high-density uranium fuel for light-water reactors

Abstract

One of the key concepts in the development of accident-tolerant fuels (ATFs) involves the use of high-density fuels, aimed at improving the safety and economics of light-water reactors. This work focuses on the microstructural and mechanical characterization of experimentally fabricated segments of dispersion-type high-density uranium fuels with a zirconium matrix and Zr-based cladding, intended for future testing in research reactors. Both U-Mo alloys and pure uranium metal were investigated, with particular attention given to the influence of thermal treatment on the phase composition and microstructure of the fuel segments. In addition, changes resulting from thermal exposure were evaluated. The research includes the identification of newly formed phases during transient conditions and the analysis of diffusion phenomena in the material. Mechanical properties were evaluated through microhardness measurements, and the results will serve as input parameters for computational simulations using the Serpent code to support the introduction of these fuels in the VR-2 research reactor.