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Étude expérimentale et modélisation du comportement en fluage sous pression interne d’une gaine en alliage de zirconium oxydée en atmosphère vapeur

Abstract : During hypothetical Loss-Of-Coolant-Accident (LOCA) scenarii, zirconium alloy fuel cladding tubes creep under internal pressure and are oxidized on their outer surface at high temperature (HT). Claddings become stratified materials: zirconia and oxygen-stabilized alpha phase, called alpha(O), are formed on the outer surface of the cladding whereas the inner part remains in the beta domain. The strengthening effect of oxidation on the cladding creep behavior under internal pressure has been highlighted at HT. In order to model this effect, the creep behavior of each layer had to be determined. This study focused on the characterization of the creep behavior of the alpha(O) phase at HT, through axial creep tests performed under vacuum on model materials, containing from 2 to 7 wt.% of oxygen and representative of the alpha(O) phase. For the first time, two creep flow regimes have been observed in this phase. Underlying physical mechanisms and relevant microstructural parameters have been discussed for each regime. The strengthening effect due to oxygen on the alpha(O) phase creep behavior at HT has been quantified and creep flow equations have been identified. A ductile to brittle transition criterion has been also suggested as a function of temperature and oxygen content. Relevance of the creep flow equations for each layer, identified in this study or from the literature, has been discussed. Then, a finite element model, describing the oxidized cladding as a stratified material, has been built. Based on this model, a fraction of the experimental strengthening during creep is predicted.
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https://hal-mines-paristech.archives-ouvertes.fr/tel-01314559
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Submitted on : Wednesday, May 11, 2016 - 3:45:33 PM
Last modification on : Friday, October 23, 2020 - 4:58:31 PM
Long-term archiving on: : Wednesday, November 16, 2016 - 1:00:16 AM

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  • HAL Id : tel-01314559, version 1

Citation

Raphaël Chosson. Étude expérimentale et modélisation du comportement en fluage sous pression interne d’une gaine en alliage de zirconium oxydée en atmosphère vapeur. Science des matériaux [cond-mat.mtrl-sci]. Mines ParisTech, 2014. Français. ⟨tel-01314559⟩

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