Study of the behaviour of zinc stearate under temperature and irradiation. Effect on lubricant properties
Description
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 (x 30) 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 amorphization 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. Gas 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 deterioration of lubricant properties observed at lower temperature compared to non-irradiated material. From these results, recommendations for use of zinc stearate have been proposed. (author)
Abstract (French)
L'elaboration de combustible nucleaire UO2-30%PuO2 pour les nouveaux reacteurs nucleaires de Generation IV repose sur l'utilisation de plutonium issu du recyclage des combustibles MOX (Melange d'OXydes UO2-PuO2) des reacteurs actuels. Par rapport au Pu initial, ce plutonium presente une proportion d'isotopes fissiles beaucoup plus faible et une quantite plus importante (x30) en 238Pu dont l'activite specifique alpha et la puissance thermique sont importantes. Le procede d'elaboration du combustible qui consiste a mettre en forme les poudres d'oxydes par pressage met en jeu un lubrifiant organique, le stearate de zinc. L'objectif de la these est d'etudier le comportement en temperature et sous irradiation de ce compose. Un effet de la montee en temperature et du vieillissement en temperature a ete observe sur les proprietes cristallographiques du stearate de zinc, avec une amorphisation partielle du materiau qui engendre une deterioration de ses proprietes de lubrification des 110 C. La degradation radiolytique du stearate de zinc a ete etudiee a travers l'analyse des gaz produits par irradiation alpha au contact de poudres de PuO2 ou par irradiation externe aux helions, completee par des analyses physico-chimiques du stearate irradie. Les rendements de production de gaz sont calcules et permettent d'etablir un mecanisme de radiolyse. Il a ete montre que l'impact de la radiolyse sur les proprietes de lubrification est moindre que l'effet de la temperature. Le couplage des degradations a un effet synergique, avec une deterioration des proprietes de lubrification observee a des temperatures plus faibles que sur le materiau non irradie. A partir de ces resultats, des recommandations d'utilisation du stearate de zinc ont ete proposees. (l'auteur)
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Additional details
Additional titles
- Original title (French)
- Etude du comportement du stearate de zinc en temperature et sous irradiation. Impact sur les proprietes de lubrification
Publishing Information
- Imprint Pagination
- 244 p.
- Report number
- FRCEA-TH--10242
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 50053607
- Subject category
- S11: NUCLEAR FUEL CYCLE AND FUEL MATERIALS; S36: MATERIALS SCIENCE;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- AGING; LUBRICATION; NUCLEAR FUELS; PLUTONIUM DIOXIDE; PRESSING; RADIOLYSIS; STEARATES; TEMPERATURE DEPENDENCE; URANIUM DIOXIDE; ZINC COMPOUNDS
- Descriptors DEC
- ACTINIDE COMPOUNDS; CARBOXYLIC ACID SALTS; CHALCOGENIDES; CHEMICAL RADIATION EFFECTS; CHEMICAL REACTIONS; DECOMPOSITION; ENERGY SOURCES; FABRICATION; FUELS; MATERIALS; MATERIALS WORKING; OXIDES; OXYGEN COMPOUNDS; PLUTONIUM COMPOUNDS; PLUTONIUM OXIDES; RADIATION EFFECTS; REACTOR MATERIALS; TRANSURANIUM COMPOUNDS; URANIUM COMPOUNDS; URANIUM OXIDES
Optional Information
- Notes
- 109 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses