Assessment of Nuclear Power Plant Power Cables Under Thermal and Mechanical Stresses

The functionality of cables is mainly related to the insulation integrity, especially when these cables placed in harsh environmental conditions like nuclear power plants. In this research, low voltage unshielded single-core power cables used in nuclear power plants have been investigated. The study was based on studying the effect of sequential stresses, thermal followed by mechanical stress on the electric properties of the samples under investigation. The capacitance, tanδ and conductivity were used as aging markers to monitor the effect of these stresses. These parameters have been measured over a frequency range from 1 kHz to 500 kHz using an impedance analyser. The results showed that there was no significant effect on the capacitance with the thermal aging while it decreased after the mechanical stress. The tanδ and conductivity increased with the aging time increase only at frequencies from 1 kHz to 5 kHz showing more leakage current dominated in the insulation.