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Currently, there are relatively few well-documented cases in which PCI directly caused damage to nuclear fuel elements. The representative cases that have been recorded are as follows: 1. The PCI-induced damage incident at Argentina’s Atucha I heavy water reactor in 1985. Background of the incident: This was a pressurized heavy water reactor; after completing one operating cycle in 1985, several natural uranium fuel elements were damaged due to core-shell interaction (PCI). Follow-up actions: The industry will subsequently use the TRANSURANUS program to conduct specialized studies on PCI failure prediction for such fuels, update the PCI model parameters tailored to these fuels, and improve the PCI risk assessment methods for heavy water reactors. II. Early large-scale PCI failures in light water reactors. Background: In the early stages of operation with zirconium alloy cladding UO₂ fuel, a number of BWRs around the world experienced batch failures of fuel elements related to PCI, which was one of the main causes of fuel failure at that time. Follow-up measures: The industry has developed two mature mitigation solutions tailored for this issue. CANLUB graphite-coated cladding is used extensively in CANDU heavy-water reactors, while Zr-lined cladding is widely adopted in BWRs, thereby significantly reducing the likelihood of PCI failures. Additional note: Cases of component failure directly caused by PCI in pressurized water reactors (PWRs) are extremely rare; this failure mode is not a major cause of fuel failure in PWRs, with only a few suspected cases occurring under certain specific power transient conditions.