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1. Gracia, Je?re?my. ?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties.

Degree: Docteur es, M?canique-mat?riaux, 2017, Paris, ENSAM

L??laboration de combustible nucl?aire UO2-30%PuO2 pour les nouveaux r?acteurs nucl?aires de G?n?ration IV repose sur l?utilisation de plutonium issu du recyclage des combustibles MOX (M?lange d?OXydes UO2-PuO2) des r?acteurs actuels. Par rapport au Pu initial, ce plutonium pr?sente une proportion d?isotopes fissiles beaucoup plus faible et une quantit? plus importante (x30) en 238Pu dont l?activit? sp?cifique alpha et la puissance thermique sont importantes. Le proc?d? d??laboration du combustible qui consiste ? mettre en forme les poudres d?oxydes par pressage met en jeu un lubrifiant organique, le st?arate de zinc. L?objectif de la th?se est d??tudier le comportement en temp?rature et sous irradiation de ce compos?. Un effet de la mont?e en temp?rature et du vieillissement en temp?rature a ?t? observ? sur les propri?t?s cristallographiques du st?arate de zinc, avec une amorphisation partielle du mat?riau qui engendre une d?t?rioration de ses propri?t?s de lubrification d?s 110?C. La d?gradation radiolytique du st?arate de zinc a ?t? ?tudi?e ? travers l?analyse des gaz produits par irradiation alpha au contact de poudres de PuO2 ou par irradiation externe aux h?lions, compl?t?e par des analyses physico-chimiques du st?arate irradi?. Les rendements de production de gaz sont calcul?s et permettent d??tablir un m?canisme de radiolyse. Il a ?t? montr? que l?impact de la radiolyse sur les propri?t?s de lubrification est moindre que l?effet de la temp?rature. Le couplage des d?gradations a un effet synergique, avec une d?t?rioration des propri?t?s de lubrification observ?e ? des temp?ratures plus faibles que sur le mat?riau non irradi?. A partir de ces r?sultats, des recommandations d?utilisation du st?arate de zinc ont ?t? propos?es.

The manufacturing of nuclear fuels UO2-30%PuO2 for the Gen IV nuclear reactors is based on the use of plutonium coming from MOX (Mixed OXides) fuel recycling from actual reactor. This plutonium would contain a few quantities of fissionable isotopes and a significant amount (x30) of 238Pu compared to initial Pu. This isotope possesses a strong alpha activity and a great thermal power. The manufacturing process which consists in powders pressing will use zinc stearate, an additive used as lubricant. The aim of this PhD is to study the behaviour in temperature and under irradiation of this compound. An effect of temperature increasing and thermal ageing has been observed on crystallographic properties with a material amorphisation and a deterioration of lubricant properties from 110?C. Radiolytic degradation of zinc stearate has been studied through the analysis of gases produced by alpha radiation at the contact of PuO2 powders or by external radiation by helions, with the support of chemical analysis of irradiated solid. Gaz production yields are calculated and enable establishment of a radiolysis mechanism. It has been showed that impact of radiolysis on lubricant properties is less important than temperature effect. The coupling of degradations has a synergic effect, with a…

Advisors/Committee Members: Colin, Xavier (thesis director), Audubert, Fabienne (thesis director).

Subjects/Keywords: St?arate de zinc; Lubrification; Pressage; Radiolyse; Combustible nucl?aire; Zinc stearate; Lubrication; Pressing; Radiolysis; Nuclear fuel

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gracia, J. (2017). ?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties. (Doctoral Dissertation). Paris, ENSAM. Retrieved from http://www.theses.fr/2017ENAM0028

Chicago Manual of Style (16th Edition):

Gracia, Je?re?my. “?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties.” 2017. Doctoral Dissertation, Paris, ENSAM. Accessed April 19, 2019. http://www.theses.fr/2017ENAM0028.

MLA Handbook (7th Edition):

Gracia, Je?re?my. “?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties.” 2017. Web. 19 Apr 2019.

Vancouver:

Gracia J. ?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties. [Internet] [Doctoral dissertation]. Paris, ENSAM; 2017. [cited 2019 Apr 19]. Available from: http://www.theses.fr/2017ENAM0028.

Council of Science Editors:

Gracia J. ?tude du comportement du st?arate du zinc en temp?rature et sous irradiation - impact sur les propri?t?s de lubrification : Study of the behaviour of zinc stearate under temperature and irradiation - Effect on lubricant properties. [Doctoral Dissertation]. Paris, ENSAM; 2017. Available from: http://www.theses.fr/2017ENAM0028

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