INVESTIGATION OF THE AGING OF CABLE INSULATION IN NUCLEAR REACTOR ENVIRONMENTS (RADIATION, ELECTRICAL, POLYMERS)

Cables used in a nuclear environment were passed through a series of accelerated laboratory aging tests, specified by the Nuclear Regulatory Commission (NRC). A set of reactor aged cables were compared against laboratory aged cables in an attempt to find a series of accelerated laboratory-aging tests which most closely correlates with the aging found in reactor-aged cables. The aging tests consisted of thermal aging, service radiation, loss of coolant, and a combination of all tests.^ An analytical procedure was developed and showed good reproducibility. The analytical procedure consisted of first determining percent swelling and percent extractables of cable insulation and jacketing material in room temprature tetrahydrofuran. The extracted materials were then separated using HPLC and GPC. The separated materials were then spectroscopically examined by FTIR.^ All methods of analysis indicated a general trend of increased crosslinking with aging. However, differences in the degree of crosslinking were found for different sequences of accelerated-aging tests. The significance of these results to the aging of cable insulation in reactor environments is discussed.