Purpose/Aim
Nuclear power has gradually received attention as an efficient and clean energy source due to the global focusing on carbon emissions. There are a large number of nuclear-grade XLPE power cables in nuclear power plants for power transmission and control. Such cables may be affected by various types of high-energy ray during operation, resulting in the decline of mechanical properties and insufficient insulation performance. Once the nuclear power cable fails to work, the reliability of the power supply will decrease, and in cases, it may cause severe safety issues. Therefore, it is necessary to further understand the degradation of XLPE insulation in the process of radiation aging, and to provide more aging mechanism support for the safety of power cables in nuclear power plants.
Experimental/Modeling methods
Samples were taken from nuclear-grade XLPE power cables, irradiated with gamma rays at different irradiation doses, and then subjected to differential scanning calorimetry, X-ray diffraction and polarization depolarization current tests. Finally, the change of crystal structure and dielectric properties were analyzed to infer the process of radiation aging.
Results/discussion
With the increase of irradiation dose, the crystal structure of XLPE becomes porous, and the electric dipole moment difference between the crystalline region and the amorphous region becomes greater, resulting in a more obvious interface polarization phenomenon.
Conclusions
The XLPE insulation in the nuclear power plant will be damaged by the crystalline region and the amorphous region due to the influence of the radiation, the connection between the crystalline regions is weakened and slippage is more likely to occur, and the increase of polar groups in the amorphous region is more obvious causing the interface polarization phenomenon.

radiation,cable,XLPE