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Etude du vieillissement hydrolytique et thermo-oxydatif de blindages neutroniques

Abstract : In radioactive materials transport/storage casks, a mineral filled vinylester composite is used for neutron shielding. The shielding ability of this compound relies on its hydrogen and boron atoms content. During the use of casks, neutrons are slowed down by hydrogen atoms, and then absorbed mainly by boron atoms. During cask service life, this composite is mainly subjected to three types of ageing: hydrothermal ageing, thermal oxidation and neutron irradiation. The aim of this study is to investigate the ageing effect on the properties and chemical composition of this polymer composite. Hydrothermal ageing is evaluated by using accelerated tests at temperatures ranging between 80°C and 140°C in a water saturated medium. The physico-chemical study shows essentially the extraction of unreacted prepolymer, hardener and oligomer and the crosslinking continuation. The well-known hydrolysis resistance of vinylester matrices is confirmed. At 120°C and 140°C, the main consequence is the strong decrease of mechanical properties induced by the filler/matrix debonding. Accelerated test of thermo-oxidation are conducted at various temperatures (120°C, 140°C and 160°C) under atmospheric pressure and 2 bar oxygen pressure. The impact of this ageing is a weight loss and the build-up of a superficial oxidized layer. A kinetic model based on the coupling of oxidation reaction/oxygen diffusion allows predicting in long term the concentration profile of oxidation products, the weight loss and the loss of hydrogen atoms. Some experiments of neutron irradiation do not show any effect on the properties and chemical composition of the composite material.
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https://pastel.archives-ouvertes.fr/pastel-00697087
Contributor : Fidele Nizeyimana <>
Submitted on : Monday, May 14, 2012 - 3:05:15 PM
Last modification on : Friday, July 17, 2020 - 2:54:12 PM
Long-term archiving on: : Friday, November 30, 2012 - 11:40:43 AM

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  • HAL Id : pastel-00697087, version 1

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Fidèle Nizeyimana. Etude du vieillissement hydrolytique et thermo-oxydatif de blindages neutroniques. Matériaux. Arts et Métiers ParisTech, 2012. Français. ⟨NNT : 2012ENAM0009⟩. ⟨pastel-00697087⟩

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