Remaining issues of the degradation models of polymeric insulation used in nuclear power plant safety cables

Aging and degradation phenomena associated with polymeric insulating materials have been investigated over the past 50 years. The results of such investigations have advanced type test procedures for qualifying the integrity of nuclear power plant safety cables. However, it has recently been determined that such advanced procedures may sometimes estimate the lifetime of cables in a significantly very short. This triggered sophisticated research on a degradation model. This paper carries out literature review on various degradation phenomena under thermal and radiation conditions, in order to attempt to interpret them using the latest degradation model, and to clarify the remaining research issues for the sophistication of test procedures.