Radio-oxidation of electric cabled models: ageing evaluation at the atomic scale

International audienceElectric cables being safety components of plants, their functionality has to be ensured. In Nuclear Power Plants when they are in the reactor building, these cables can suffer γ irradiation even in normal operation conditions. Their ageing behavior has to be well understood to be able to determine a precise end-of-life criterion. As polymers are the most radiosensitive material of the cables, this paper focus on the ageing of this kind of material and more specifically on the ageing of silane-crosslinked polyethylenes (XLPE). XLPE are now one of the most employed polymers to manufacture cables. We performed irradiation under oxidative conditions of few model silane-crosslinked polyethylenes with different additives and filler: at three different doses (0, 67, 220 and 374 kGy) for one dose rate (78 Gy.h$^{-1}$) and at one dose (67 kGy) for three dose rates (8.5, 78 and 400 Gy.h$^{-1}$). Modifications in the organic materials were followed by X-ray photoelectron spectroscopy. This analytical technique allows to follow the evolution of the different chemical products formed under irradiation. A better understanding at the atomic scale of the effect of additives on the degradation of polymers will be proposed, as a function of the ageing conditions