PREDICTIVE MODEL OF THE DEGRADATION OF CABLE INSULATION SUBJECT TO RADIATION AND TEMPERATURE

摘要

A physics-based model is developed to represent the elongation at break (EAB) of cable insulation subject to temperature and radiation in Nuclear Power Plants (NPPs). It addresses a safety concern about the degradation of critical cables in long term exposure to radiation, particularly in the context of plant life extension. The proposed model provides a theoretical basis for the EAB curve as a function of time. The curve is divided into two phases: the incubation phase where the virtual degradation rate is indiscernible, and the degradation phase in which the virtual degradation rate is considered constant. When the parameters of the model are modified according to a specific material, the EAB curves at different ageing temperatures and dose rates can be predicted. Data of two widely-used insulating materials is incorporated in this research to validate the proposed model. They are cross-linked polyethylene (XLPE) and ethylene propylene rubber (EPR). Besides fitting the experimental data well, the developed model can also render the value of the activation energy of a degradation progress, which is a necessary parameter in accelerated ageing experiments predicting the remaining life of a material.