Radiation-Induced Degradation in Polymeric Materials: Alterations in Physical–Chemical Properties and Their Effects on Electrical Performance of Insulation Systems

This paper investigates the effects of radiation on polymeric materials used as insulation systems in electrical equipment such as cables for nuclear and particle accelerator applications. After a detailed description of the physics of radiation-induced damage in the polymeric matrix, a comprehensive analysis of the physical–chemical and electrical properties of aged materials is carried out, ranging from the microscopical ones (e.g., variation in crystallinity) to macroscopical ones (e.g., mechanical and electrical properties). In particular, significant attention is given to the electrical tests aiming at investigating the impact of free charges and radicals, induced by radiation, on conductivity and permittivity variations of the studied insulation system. The results show that electrical properties may successfully be correlated with state-of-the-art condition monitoring techniques, for example, oxidation level and mechanical resistance, suggesting the possibility to use electrical quantities as a diagnostic method for the nondestructive evaluation of the electrical equipment ageing state.