3Y-TZP Toughened and Oxidation-resistant U3Si2 Composites for Accident Tolerant Fuels

Abstract In this work, we report an innovative approach synergizing multiple effects of microstructure control, oxide protection and phase transformation-induced mechanically toughening to develop advanced U3Si2 fuels with state-of-the-art materials properties. 3Y-TZP (3 mol% yttria doped stabilized tetragonal zirconia) additives are incorporated and uniformly distributed into the SPS-densified U3Si2 fuel matrix, enhancing materials fracture toughness up to 4.04 MPa m1/2. The 3Y-TZP incorporated U3Si2 composite pellets show significantly improved onset temperature of oxidation above 560 °C, which can be further improved to 617 °C with 3 vol% addition by post-sintering thermal annealing. The development of mechanically tough and oxidation-resistant U3Si2 with minimal additive represents a major step forward towards realizing the potential of high density U3Si2 as the leading fuel concept to increase accidence tolerance of nuclear energy systems.