U₃Si₂ is being considered as a potential fuel candidate for water cooled power reactors. Herein, we examine the oxidation behavior and phase separation of U₃Si₂ under flowing steam to understand the fuel degradation mechanism in the event of a steam ingress through cracks in cladding. The weight gain, microstructure evolution, and phase change after isothermal annealing were investigated for spherical U₃Si₂ particles fabricated by centrifugal atomization. Equilibrium oxide products and their compositional changes with increasing degree of oxidation were predicted using thermodynamic calculations and compared with experimental results. It was seen that the oxidation reaction of U₃Si₂ in steam begins with dissociation into UO₂ and Si, followed by Si being partially oxidized to amorphous SiO₂. From these results, an oxidation mechanism of U₃Si₂ in steam is proposed. The theoretical volume expansion of U₃Si₂ during the steam oxidation was estimated and its impact on fuel performance is also discussed.

U ₃ Si ₂被认为是水冷动力堆的潜在燃料候选者。在此，我们检查流动的蒸汽下U ₃ Si ₂的氧化行为和相分离，以了解蒸汽通过覆层裂缝进入时燃料的降解机理。研究了离心雾化制备的球形U ₃ Si ₂粒子的重量增加，微观结构演变和等温退火后的相变。使用热力学计算预测了平衡氧化产物及其随氧化程度增加的组成变化，并与实验结果进行了比较。可以看出U的氧化反应₃蒸汽中的Si ₂开始分解为UO ₂和Si，然后Si被部分氧化为非晶SiO ₂。根据这些结果，提出了U ₃ Si ₂在蒸汽中的氧化机理。估算了蒸汽氧化过程中U ₃ Si ₂的理论体积膨胀，并讨论了其对燃料性能的影响。