Micro-plate or microcell UO2–Mo is considered a promising accident tolerant fuel candidate for water-cooled power reactors. In this work, we evaluated the anticipated oxidation behavior of a UO2–Mo system under high-temperature steam to understand the impact of Mo oxidation on the fuel degradation mechanism in the event of steam ingress through cracks in the cladding. The equilibrium oxygen compositions of UO2 and Mo in various steam atmospheres relevant to reactor operating conditions were predicted using thermodynamic calculations and then compared with previous results. The oxidation behavior of UO2–Mo pellets was discussed through thermodynamic calculations and in terms of kinetic parameters such as oxygen diffusion, fuel temperature profile, and pellet microstructure. Mo oxidation was found to have an insignificant effect on pellet integrity in a cladding leakage scenario under normal reactor operating conditions.

中文翻译：

---

高温蒸汽下UO 2 - Mo 核燃料芯块平衡氧组成的热力学评价

微板或微电池 UO2-Mo 被认为是一种有前途的水冷动力反应堆的容灾燃料候选者。在这项工作中，我们评估了 UO2-Mo 系统在高温蒸汽下的预期氧化行为，以了解在蒸汽通过包壳裂纹进入的情况下，Mo 氧化对燃料降解机制的影响。使用热力学计算预测 UO2 和 Mo 在与反应器操作条件相关的各种蒸汽气氛中的平衡氧组成，然后与之前的结果进行比较。通过热力学计算和动力学参数，如氧扩散、燃料温度分布和球团微观结构，讨论了 UO2-Mo 球团的氧化行为。