Investigating the Impact of γ-Ray Radiation on the Aggregate Structure and Interfacial Polarization Properties of XLPE

During operation within nuclear power plants (NPPs), the insulation of cross-linked polyethylene (XLPE) cables can progressively degrade due to radiation exposure, potentially resulting in insulation failure. This research explores the influence of various radiation doses on the aggregate structure and interfacial polarization characteristics of XLPE. Samples are subjected to γ-ray irradiation at varying doses, followed by a series of tests to scrutinize alterations in aggregate structure and polarization characteristics. The study's findings indicate that as the radiation dose escalates, XLPE experiences a 7.87% decline in crystallinity. Contrarily, both crystallite size and crystal plane spacing exhibit increase exceeding 20%. These outcomes suggest that while the crystalline region of XLPE becomes less dense, it remains intact. The reduction in XLPE's mechanical properties following irradiation unfolds through three discernible stages. Among these, the rapid degradation primarily results from the disruption of molecular chains responsible for interconnecting lamellar structures, thereby heightening the likelihood of crystal slippage. Additionally, oxidation and chain fragmentation yield an augmented presence of oxygen-containing groups with more substantial electric dipole moments, subsequently amplifying the interfacial polarization phenomenon.