Thermomechanical evaluation-Guided structural design and porous interface optimization of multilayer heterogeneous cladding

In advanced nuclear reactors, refractory metal-SiCf/SiC multilayer cladding is considered to be a promising accident-tolerant fuel cladding because it overcomes the gas-tightness limitation of SiCf/SiC cladding. However, the mechanisms by which structural changes affect their thermomechanical properties are unclear, and the excessive interface stress remains a major obstacle to their application. In this study, a parametric modeling approach was employed to rapidly construct 15 heterogeneous cladding structures with 2D braided SiCf/SiC composites, incorporating five types of metal liners (W, Mo, Re, Ta, Nb) at three different thickness levels. Their thermo-mechanical properties were systematically analyzed using finite element simulation at RT, 450 °C, 1000 °C, and 1200 °C. The results show that among the five metal liner systems, the Re- and W- lined systems exhibit superior overall performance in the non-irradiated state, with their thermomechanical properties consistently improving as liner thickness increases. In contrast, the Mo-, Ta-, and Nb-lined systems display inconsistent trends. Notably, the Re-lined cladding consistently shows the highest interfacial thermal stress across all temperature conditions. To effectively alleviate this issue, a porous SiC interlayer was designed, optimized and successfully fabricated, resulting in a ∼30 % reduction in interfacial stress. This study provides theoretical foundations and design guidelines for enhancing the inherent safety of advanced reactors and optimizing the structural parameters of nuclear-grade SiCf/SiC heterogeneous claddings.