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Zirconium alloy cladding is prone to corrosion under the following conditions: 1. High-temperature and high-pressure water environments. Water/steam at temperatures above 450°C accelerates pustular corrosion; the corrosion rate increases exponentially with each 50°C rise in temperature, with the corrosion rate at 650°C being 3.2 times that at 550°C. In a supercritical water environment above 300°C, the oxidation reaction of zirconium alloys intensifies further. 2. High dissolved oxygen conditions: When the dissolved oxygen level in the coolant exceeds 1000 μg/L, transverse cracks can appear in the oxide film, and the self-corrosion current density increases significantly, accelerating the processes of uniform corrosion and pustular corrosion. Chromium-coated zirconium alloys undergo significant oxidative dissolution in high-temperature water with a DO level of >300 ppb; after prolonged exposure, the coating peels off, losing its protective function for the substrate. 3. Special water chemistry conditions: Excessively high concentrations of LiOH in the coolant, as well as the presence of impurities such as fluoride ions, can damage the integrity of the oxide film and accelerate the corrosion and degradation of zirconium alloys. Under conditions such as shutdown, startup operations, and fuel pool immersion, fluctuations in the chemical composition of the coolant water also increase the risk of corrosion. 4. Irradiation and special mechanical environments: Intense irradiation within the reactor core induces chemical changes in the coolant water, simultaneously lowering the self-corrosion potential of zirconium alloys and accelerating the processes of fretting wear and galvanic corrosion. The contact stress between the fuel pellet and the cladding, combined with the effect of fission product iodine, can induce iodine-induced stress corrosion cracking, leading to cladding failure.