Aging Investigation of Low-Voltage Cable Insulation Used in Nuclear Power Plants

This paper deals with the effect of a long storage time after thermal and radiation aging on electrical and mechanical properties of insulating materials used in nuclear power plant cables. Strong post-irradiation effects were found on XLPE cable insulation years after irradiation. In particular, a dramatic reduction of mechanical properties was observed, suggesting insulation crosslinking and/or oxidation, as well as an increase of the imaginary permittivity values, particularly in the low frequency range where interfacial phenomena are active. This latter could be associated likely to the increase of interface between amorphous and crystalline regions, thus supporting the evidence that post-irradiation effects may provide mostly polymer crosslinking during storage time at room temperature.