PROPRIETES CHIMIQUES DE L'AMERICIUM DANS L'EUTECTIQUE LICL + KCL FONDU-APPLICATION A LA SEPARATION AMERICIUM-LANTHANIDES (NEODYME)

PARIS-BIUSJ-Thèses (751052125) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

1H NMR study of saponification kinetics of vegetable oils during its incorporation in geopolymer materials

National audienc

1H NMR quantification of hydrolyzable cutting fluids incorporated in geopolymer materials

National audienc

Trapping performance of alkali-activated materials incorporating a hydrogen/tritium getter for the conditioning of tritiated organic liquids

International audienceIn this research, novel alkali-activated materials (AAM) are assessed for the conditioning of tritiated organic liquids OL. Their originality is to ensure both the conditioning of radioactive OL waste and the trapping of hydrogen or tritium (1H2 or 3H2). Two types of AAM are compared, either based on metakaolin MK (i.e., on geopolymer GEO solid structure) or on blast furnace slag BFS (i.e., Portland cement solid structure). For the trapping of 1H2 or 3H2, both AAM incorporate a γ-MnO2/Ag2O getter powder at 10 wt.%.The efficiency of 1H2 trapping in the two AAM is quantified via in situ 1H2 production, using two distinct methods: (1) gamma irradiation (short term 1H2 production) and (2) magnesium metal Mg corrosion (longer term 1H2 production). Complementarily, the 1H2 trapping efficiency of the getter is analyzed in both AAM porewaters.Gamma irradiation with a cumulated dose up to 500 kGy shows that GEO-based AAM added with getter have a H2 trapping efficiency of almost 100% without OL, and 87–92% with OL, when compared to identical materials made with non-trapping γ-MnO2. BFS-based AAM made with getter have a trapping efficiency of 52–65% without OL and 16–25% with OL.After 443–464 days of Mg corrosion, the cumulated amount of 1H2 trapped in BFS AAM reaches an asymptote of 0.7 mmol/g of getter, but it keeps increasing in GEO AAM. This proves the excellent 1H2 trapping efficiency of getter-functionalized GEO, compared to BFS AAM.Finally, the contact of the getter with the extracted porewaters of the two AAM shows a strong adsorption of ions on its surface. In both AAM, this reduces the 1H2 trapping capacity by 50%. When the getter is placed in contact with sulfides, which are present in BFS AAM only, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) evidence that the structure of the getter is modified. This explains the limited 1H2 trapping efficiency of the getter in BFS AAM, whereas the getter-functionalized GEO AAM remains efficient

Determination of the solubility product of plutonium sesquioxide in the NaCl+CaCl2 eutectic and calculation of a potential–pO2− diagram

Reactions between plutonium trichloride and oxide ions were studied in the fused NaCl+CaCl2 equimolar mixture at 823 K, by potentiometry with an yttria-stabilised zirconia membrane electrode. Titration curve demonstrated the existence of a precipitated plutonium oxide (Pu2O3) with dissociation constant 10−17.5 (molality scale). The combination of this data with the standard potentials allowed to set up the potential–pO2− diagram of plutonium which summarises the properties of plutonium species in the melt. Keywords: Plutonium, Molten salt, Nuclear energy, Solubility measurements, Equilibrium diagram

1H NMR quantification of glycerol achieved by the saponificartion of vegetable oil during the incorporation in geopolymers

National audienc

Incorporation of organic liquids into geopolymer materials - A review of processing, properties and applications

Geopolymers, composed of an amorphous three-dimensional inorganic network and synthesized by the activation of a solid alumino-silicate precursor with an alkaline activating solution, have attracted increasing attention because of their environmental benefits and favorable characteristics. This review deals with the development of organic/inorganic composite materials made by adding organic liquids into inorganic geopolymer matrices. Firstly, the incorporation processing approaches are presented and are divided into three categories: (i) Direct incorporation, (ii) Pre-emulsification (iii) Solid impregnation. Their main advantages and drawbacks are discussed in relation to the aimed properties. Secondly, this review highlights that geopolymers are low-cost candidates allowing technologically significant applications, through the incorporation of various organic liquids. Aside from the well-studied immobilization of industrial waste streams commonly known as stabilization/solidification (S/S), the development of highly porous geopolymer foams and the design of reinforced organic/inorganic composite matrices are being notably investigated. This review aims at summarizing the main published results, and fostering further investigations into innovative uses of organic liquids incorporated into geopolymers for a wide range of applications

Characterization of hydrolyzable nuclear organic waste prior to their immobilization in geopolymers by quantitative 1H NMR

International audienc

Dismutation of divalent americium induced by the addition of fluoride anion to a LiCl–KCl eutectic at 743 K

The three oxidation states of americium (III), (II) and (0) are stable in a molten LiCl–KCl eutectic at 743 K. Addition of fluoride anion to the melt led to the disproportionation of Am2+ into Am3+ and Am. The effect of fluoride additions was monitored with potentiometric and cyclic voltammetry methods and the relative cumulative formation constants of the Am(III) fluoro-complexes determined. Keywords: Americium, Molten salt, Fluoride complexatio

Influence of MnO2 polymorphism form on MnO2/Ag2O hydrogen getter

International audienceWe investigate the influence of MnO2 polymorphism form on MnO2/Ag2O hydrogen getter. The results show that the performances strongly depend on the polymorphism form of manganese oxide. The nsutite γ-MnO2 phase, which consists of a random intergrowth of MnO2-ramsdellite and MnO2-pyrolusite building blocks, shows the more promising performances to trap H2 via the formation of hydroxyl groups. This observation is especially relevant for compounds with a low pyrolusite/ramsdellite ratio and a high rate of microtwinnings