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

This paper presents some preliminary results of test carried out to measure electrical properties of XLPE insulations used at nuclear power plants (NPP). These cables were aged under thermal and radiation stresses. In order to obtain significant results in a reasonable time, the dose rate and the temperature chosen were higher than the operation values. Electrical measurements were performed through dielectric spectroscopy and polarization/depolarization currents. First results show significant variations of electrical properties of aged cables which can be correlated to insulation aging. In particular, the real part of the permittivity increases noticeably with aging over the whole test frequency range and the imaginary part of the permittivity shows a polarization peak enhancing at very low frequencies.