Investigation of Inverse Temperature Effects During Thermal-Radiation Aging of Semicrystalline Cable Insulation

Abstract

Inverse temperature effects (ITE) were observed for semi-crystalline polymers subjected to combined thermal and irradiation aging. In the case of ITE, the mechanical durability of materials aged at lower temperatures degrades with dose faster than at higher temperatures. In this paper, two crosslinked polyethylene (XLPE) and two ethylene-propylene rubber (EPR) type nuclear cable insulations were exposed to thermal-radiation aging at 100 Gy/h up to 30 Mrad and at three temperatures $(26 ^{\circ}\text{C}, 50 ^{\circ}\text{C}, 90 ^{\circ}\text{C})$. Their mass change and color change after aging were analyzed for indication of ITE.