Exceptional irradiation and corrosion resistances of a TaC nanoceramic coating deposited onto ZIRLO™ fuel cladding

Abstract Improving the accident tolerance of zirconium-based nuclear fuel claddings is essential to mitigate oxidation-driven hydrogen generation under loss-of-coolant conditions. Here, a nanostructured tantalum carbide (TaC) ceramic coating is deposited onto ZIRLO™ fuel cladding by non-reactive DC magnetron sputtering. The coating was systematically assessed with respect to its microstructural stability, irradiation tolerance, and corrosion behaviour. Characterisation of as-deposited coating confirms a dense, nanocrystalline B1-type TaC structure with excellent adhesion and negligible interdiffusion at the coating-substrate interface. In situ transmission electron microscopy with heavy-ion irradiation up to ~8 dpa reveals exceptional radiation resistance, with no evidence of amorphization, phase decomposition, or radiation-induced segregation. Limited grain coarsening and the formation of Xe bubbles (~2 nm) were observed. Electrochemical measurements in borated aqueous media demonstrated rapid passivation, very low corrosion current densities, and high impedance over prolonged exposure. These results identify nanostructured TaC as a robust and scalable candidate coating for accident-tolerant fuel cladding systems.