Durability of PE in nuclear environment

The durability of PE in a nuclear environment, especially at mild exposure conditions, i.e. at low dose rates, low temperatures (< 50 deg C) and in air, is of economic and security importance. To resolve difficulties of extrapolating accelerated ageing to the actual operational conditions, we propose a general kinetic model based on a standard mechanistic scheme in which initiation by hydroperoxide decomposition as well as radiochemical initiation are taken into account. The model involves classical simplifications (steady , long kinetic chains, relationship between the termination rate constants, etc.). Methods for obtaining the necessary kinetic parameters are presented. The model is confronted with published experimental data. Simulations made for thermal, radiation and radiation-thermal oxidations are in a satisfactory agreement with the experimental results. Improvements and perspectives of the proposed modelling in durability prediction are also presented