Architecture-Controlled Accident-Tolerant Fuel Cladding: From Surface Modification to Transition Multilayer Tubes

초록

The 2011 Fukushima accident highlighted the vulnerability of zirconium (Zr) alloy cladding to rapid oxidation and hydrogen generation under high-temperature steam conditions, accelerating the development of accident-tolerant fuel (ATF) cladding. This review examines ATF cladding technologies from a manufacturing-architecture perspective, emphasizing how processing routes define defect connectivity, interfacial evolution, long-tube uniformity, and qualification-relevant limitations. Vacuum-deposited Cr coatings are treated as a mature benchmark for outer-diameter (OD) protection, not as a universal solution, because they provide the most developed process-defect-interface datasets for Zr-based cladding. Nonvacuum approaches, including cold spray and electrodeposition, are then compared by separating inner diameter (ID) accessibility in principle from experimentally validated ID protection in long tubular geometries. Cold spray offers high-rate metallic layer buildup on accessible surfaces, whereas electrodeposition provides direct electrolyte-mediated access to confined surfaces; however, both routes require further validation of defect control, thickness uniformity, and long-tube reproducibility. Swaging-drawing methodology (SDM) is distinguished from coating-based routes because it incorporates ID-facing functionality into the tube architecture rather than forming a layer in situ on a confined surface. Building on these comparisons, conceptual transition multilayer architectures such as FeCrAl/Zr/FeCrAl are discussed as design extrapolations from available constituent- and interface-level evidence, with the aim of exploring partial material substitution and distributed protection. Their promise lies in redistributing oxidation-resistant and diffusion-controlling functions across the cladding cross section, whereas their engineering readiness depends on interfacial stability, buried-interface inspection, irradiation tolerance, fuel-cladding compatibility, and staged qualification testing. By organizing ATF cladding technologies according to evidence level, geometry, defect descriptors, interface state, scale-up readiness, and degradation mode, this review provides a critical framework for comparing current and emerging cladding architectures.

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