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I. Common types of corrosion in zirconium alloy cladding: Uniform corrosion on the water side: When zirconium alloy comes into contact with the coolant, an oxide film is formed. Under normal operating conditions, this dense oxide film protects the underlying material; however, increases in temperature and oxygen content accelerate corrosion, causing the oxide film to change from a dense black structure to a looser one. Furuncular corrosion: It is a typical type of localized non-uniform corrosion in pressurized water reactors, characterized by the formation of white oxidative spots with diameters of over 0.5 mm; it progresses rapidly in environments with high temperatures above 450°C and high dissolved oxygen levels. Hydrogen embrittlement corrosion: The hydrogen generated by the reaction between zirconium and cooling water is absorbed by the matrix, leading to the formation of brittle hydrides that can facilitate crack propagation; therefore, it is necessary to keep the hydrogen absorption rate during operation within the range of 250–500 μg/g. Stress corrosion cracking: Under the combined effect of the mechanical contact stress between the core and the cladding, as well as corrosive fission products such as iodine and cesium, local cracking and failure of the cladding can occur. II. Corrosion protection and optimization methods: Composition optimization – by adjusting the ratios of elements such as Nb, Mo, and Cu, new zirconium alloys such as N36 and N45 have been developed, significantly enhancing their corrosion resistance. Surface coating modification: A chromium-based coating is deposited on the surface of the zirconium alloy; under normal low-oxygen conditions, a dense Cr₂O₃ protective film is formed, which significantly enhances the material’s corrosion resistance and high-temperature oxidation resistance. Process control: By adjusting rolling and annealing parameters to optimize the size of the second-phase particles to 70–90 nm, the occurrence of pustular corrosion can be effectively suppressed. Water chemistry control: Maintain a low dissolved oxygen level in the coolant (DO