Aging Assessment of XLPE/CSPE LV Nuclear Power Cables Under Simultaneous Radiation–Mechanical Stresses

The preliminary results of an ongoing laboratory cable aging program are reported in this article. This work deals with the effect of simultaneous radiation–mechanical​ aging on the electrical and mechanical properties of XLPE/CSPE low-voltage unshielded nuclear power cables. The dielectric response, particularly the complex permittivity and the polarization/depolarization current (PDC), were investigated. At the same time, the Shore D hardness measurement was conducted as a mechanical property test. Cable samples were coincidingly aged under a bending diameter of 15 cm and a total dose of 240 kGy γ-irradiation at a 0.5 kGy/h dose rate. The real and imaginary parts of permittivity were investigated over a frequency range from 200 μHz to 1 Hz. The electrical parameters presented a monotonic increase with aging. Besides, the cable hardness has increased with increasing the radiation dose. Furthermore, the insulation conductivity has risen with aging, which strongly correlates with the imaginary permittivity at 1 mHz. The obtained results showed an excessive degradation of the cable samples under the combined radiation–mechanical aging as the insulation electrical and mechanical properties showed a good agreement.