Degradation of Silicon Rubber-based Nuclear Power Plant I&C Cable under Accelerated Thermal Aging

The degradation behavior of SiR-insulated cable samples under accelerated thermal stress has been investigated in this research work. The cable samples were taken from NPP-based I&C cable and were exposed to 155°C for three aging cycles. The variation in the insulation was evaluated by applying dielectric spectroscopy in the frequency range of 1kHz to 5 MHz where the capacitance and tanδ were investigated. Microhardness was also adapted to help elucidate the degradation in the insulation. The effect of thermal aging was observed in the form of a chemical cross-linking reaction as at most of the frequency points the tanδ and capacitance values decreased. The microhardness results also reflected the degradation of the SiR material, where the hardness of the material decreased with aging.