Ageing monitoring of plastics used in nuclear power plants by DSC

Degradation of polymeric materials used in nuclear power plants (NPP), espe cially polymeric cable insulation materials, in the course of their service can be monitored by measuring their properties by DSC, mainly oxidative in duction time - OIT. The studied materials were in-laboratory aged by applyi ng main stressors that act in NPP - ionising radiation and temperature. The dependence of OIT on radiation and thermal degradation of polymeric materi al was determined. The OIT values have been compared to elongation at break as a property that directly reflects the functionality of the studied mate rial. The comparison of monitored OIT of real cable samples taken from NPP with dependencies on how the OIT values change with the elongation at break , makes possible to establish the extent of cable degradation. This method can be considered as a suitable and effective technique for lifetime assess ment not only of cable insulations but also of many other plastics.