Mécanisme d'oxydation / dissolution du dioxyde d'uranium

Conférence du 02 au 06 juillet 2007. Communication par affiche

Influence de la température sur le couple rédox Ce(IV) / Ce(III) en milieu Na2CO3 / NaHCO3 concentré entre 15 et 50°C

Conférence du 02 au 06 Juillet 2007. Communication par affiche

Modelisation du comportement electrochimique du plutonium en milieu acide nitrique

National audienc

Relative stabilities of Ce(IV) and Ce(III) limiting carbonate complexes at 5 to 50°C in Na+ aqueous solutions, an electrochemical study

Communication par affich

Electrochemical behavior of plutonium in nitric acid media

International audienceThe first step of the spent nuclear fuel reprocessing is a dissolution of actinides and fission products in hot nitric acid at high concentration. Among all these species, the knowledge of redox plutonium equilibria with discerning between their oxidation states is essential to understand and depended on many chemical conditions. Nevertheless, the knowledge of speciation in this media is a challenge especially for a better understanding of corrosion mechanism in the dissolution medium. Thus this paper proposes to determine the electrochemical behaviour of plutonium and especially the Pu(IV)/Pu(III), Pu(VI)/Pu(V) and Pu(V)/Pu(IV) redox couple in nitric acid media and acquire thermodynamic and kinetic constants at higher temperatures than 25C and higher nitric concentration than 1 mol L−1

Redox Potential Evolution of Nitric Species and Plutonium in HNO3

International audienceIn France, the reprocessing process of spent fuel is carried out using the Purex process. The first chemical step of this process is the dissolution of the spent fuel in aqueous concentrated nitric acid. This dissolution solution is composed of many oxidizing species and it is necessary to understand the chemistry of these species to apprehend the behavior of structural materials. The redox potential is a useful discriminate variable to differentiate the effect of each species. In this framework, only the effect of NO 3-/HNO 2 couple and PuO 2 2+ /Pu 4+ couple were investigated. These species were chosen because one is the main couple of medium and the other has a high standard potential. Their influence was investigated from the Nernst's equation

Dosage de traces d'uranium(VI) dans des eaux d'environnement

Conférence du 02 au 06 juillet 2007. Communication par affiche

Towards a reliable determination of the intergranular corrosion rate of austenitic stainless steel in oxidizing media

International audienceThis paper studies the corrosion behaviour of non-sensitized stainless steels in oxidizing environments, where they can suffer intergranular corrosion. In this case, corrosion rate estimated by gravimetric measurement is not constant as a function of time. This paper proposes a quantitative modelling of the IGC kinetics. Two models were developed: the first one is based on the geometrical simulation of the groove penetration; the second one uses a semi-empirical approach based on the typical shape of the corrosion kinetics. Both models reproduce successfully the experimental corrosion kinetics observed for AISI 310L SS corroded in nitric acid containing oxidizing ions

Discussion on the relation-ship between passivity and reactivity of metals

International audienc