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The interaction between the cladding and the fuel pellets (abbreviated as PCI) is one of the key mechanisms leading to the failure of nuclear fuel elements; it is a failure process caused by a combination of mechanical and chemical effects. I. Core mechanism of action: Mechanical interaction (PCMI): Under irradiation, the fuel pellets expand thermally, swell, and crack; fragments become trapped in the gaps between the pellets and the cladding, resulting in localized stress concentration in the cladding and leading to excessive strain in it. Chemical interactions: In environments with high burnup and high temperatures, corrosive substances such as iodine produced by fission can cause stress corrosion cracking in the cladding; this, combined with mechanical stress, accelerates crack propagation, ultimately leading to the failure of the cladding. II. Key influencing factors: The risk of damage is directly related to five operational parameters: the fuel consumption accumulated before a sudden increase in power, the maximum rod power during such an increase, the rate of power increase, the average rate of increase in power, and the duration of operation at high power levels. When these parameters are all within critical ranges, the probability of damage increases significantly; components with high fuel consumption are particularly prone to such damage. III. Engineering control measures: The operating specifications for nuclear power plants strictly limit the rate at which the reactor capacity can be increased. Meanwhile, design improvements such as optimizing the structure of the fuel element shoulders and using chromium-reinforced cladding coatings are employed to reduce contact stress, thereby significantly lowering the risk of component failure caused by PCI.