Electrical aging markers for EPR-based low-voltage cable insulation wiring of nuclear power plants

• Radiation and temperature affect electric properties of cable insulation.
• Good correlation between electric and mechanical properties.
• Electric properties, e.g. imaginary permittivity, can be used as aging marker.

This paper presents results of electrical property measurements on EPR-based insulations of low-voltage power cables used in nuclear power plants. The specimens underwent accelerated aging through the simultaneous application of high temperature and gamma-radiation. Mechanical properties and the dielectric response at different frequencies were investigated. Results showed significant variation of the electrical and mechanical properties of aged cables at low frequencies, i.e. lower than 10−2 Hz. In particular, the real and imaginary parts of permittivity increase with aging time, accumulated dose and stress levels applied showing good correlation with elongation at break, which decreases as a function of extent of insulation aging.