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4. Peroxide co-conversion as an original route for mixed (U,Pu)O2 pellet fabrication

Author

Hibert, N., Arab-Chapelet, B., Rivenet, Murielle, Venault, L, Medyk, L, Martin, P, Lebreton, F, Tougait, Olivier, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM]Chemical Sciences
Abstract

International audience

Published
2022

5. Humin decomposition by γ-irradiation – a promising strategy for catalyst regeneration

Author

Medina, N., Girardon, Jean-Sébastien, Hablot, I., Guilbaud, P., Venault, L, Cornet, S., Pacary, V., Katryniok, Benjamin, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM]Chemical Sciences
Abstract

International audience

Published
2022

9. Synthèse et caractérisation structurale de complexes de plutonium à base de ligands peroxyde

Author

Hibert, Nicolas, Rivenet, Murielle, Tougait, Olivier, Tamain, C., Vauchy, R., Hennuyer, Nathalie, Brethenoux, V., Arab-Chapelet, Bénédicte, Venault, L., Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Récepteurs nucléaires, maladies cardiovasculaires et diabète - U 1011 (RNMCD), Institut Pasteur de Lille, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), and Université de Lille, LillOA

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2019

10. Particle Size vs. Local Environment Relationship for ThO2 and PuO

Author

Bonato, L., Virot, M., Dalodiere, E., Dumas, T., Mesbah, A., Dieste Blanco, O., Wiss, T., Prieur, D., Rossberg, A., Venault, L., Moisy, P., Nikitenko S, I., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and CADARACHE, Bibliothèque

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], actinides, plutonium, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], nanoscale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], DWF, thorium, EXAFS, nanostructuration, oxides, TEM, nanoparticles
Abstract

International audience; Nanomaterials have attracted considerable interest in recent interdisciplinary research for their technological applications related to the nanometric size of the building blocks composing the solids (ex crystallite or atomic and molecular groups).[1,2] Nanostructured materials can be defined as solid samples exhibiting a microstructure the characteristic length scale of which is roughly ranging between 1 and 10 nm.[1] The controlled microstructure of materials at the atomic level offers new physical and chemical properties in comparison to similar bulk materials already applied, for instance, in catalysis, synthesis of luminescent materials, preparation of cosmetic and solar creams, preparation of solar cells, etc.[3,4] Such paradigm has been attributed to the increased surface-to-volume ratio of the shrinking particle size which increase the number of surface and interface atoms generating stress, stain, and structural perturbations.[2] In actinide chemistry, the synthesis and characterization of nanomaterials is very scarce but is of growing interest due to the contribution of actinide nanomaterials in environment (ex migration of actinides) and industry (ex high burn up structures). Recently, we observed the nanostructuration of PuO2 and noticed its outstanding reactivity under ultrasound irradiation which stirred up our curiosity concerning the local environment of this oxide at the nanoscale.[5] In this work, we investigate the synthesis and relevant characterization of nanostructured PuO2 and ThO2. Th can be considered as a good surrogate for Pu because both elements exhibit close ionic radii, their oxide crystallize in the fluorite Fm-3m structure, and they both exist at the (+IV) oxidation state. More precisely, Th only exists at the +IV oxidation state thus avoiding misinterpretations related to the potential contribution of other oxidation states in the crystalline structure. The synthesis studies allowed us to select the nanostructuration conditions for the various oxides and a careful characterization and correlation with AFM, HR-TEM, Raman spectroscopy, XRD and XAS techniques allowed us to probe the local disorder for the various oxides as a function of the particle size. Particularly, EXAFS investigations clearly show a linear decrease of the coordination number for An-O and An-An spheres with the shrinking particle sizes. The crystalline nature of the particles (HR-TEM, XRD) suggest that these observation are correlated to the increasing surface contribution of these particles. These new results raise the question of the physico-chemical properties of oxide nanomaterials crystallizing in the fluorite structure which are materials of paramount importance for engineering applications such as nuclear energy, solid oxide fuel cells, catalysis, or sensors.

Published
2019

11. Probing the Local Structure of Nanoscaled Actinide Oxides: A Comparison between PuO2 and ThO2 Nanoparticles Rules out PuO2+x Hypothesis

Author

Bonato, L., Virot, M., Dumas, T., Mesbah, A., Dalodière, E., Dieste Blanco, O., Wiss, T., Le Goff, X., Odorico, M., (0000-0001-5087-0133) Prieur, D., Roßberg, A., Venault, L., Dacheux, N., Moisy, P., Nikitenko, S. I., Bonato, L., Virot, M., Dumas, T., Mesbah, A., Dalodière, E., Dieste Blanco, O., Wiss, T., Le Goff, X., Odorico, M., (0000-0001-5087-0133) Prieur, D., Roßberg, A., Venault, L., Dacheux, N., Moisy, P., and Nikitenko, S. I.

Abstract

Actinide research at the nanoscale is gaining fundamental interest due to environmental and industrial issues. The knowledge of the local structure and speciation of actinide nanoparticles, which possibly exhibit specific physico-chemical properties in comparison to bulk materials, would help in a better and reliable description of their behavior and reactivity. Herein, the synthesis and relevant characterization of PuO2 and ThO2 nanoparticles displayed as dispersed colloids, nanopowders or nanostructured oxide powders, allow to establish a clear relationship between the size of the nanocrystals composing these oxides and their corresponding An(IV) local structure investigated by EXAFS spectroscopy. Particularly, the probed An(IV) first oxygen shell evidences an analogous behavior for both Pu and Th oxides. This observation suggests that the often observed and controversial splitting of the Pu-O shell on the Fourier transformed EXAFS signal of PuO2 samples is attributed to a local structural disorder driven by a nanoparticle surface effect rather than to the presence of PuO2+x species.

Published
2020

14. Synthèse et caractérisation structurale de complexes de plutonium à base de ligands peroxyde

Author

Hibert, Nicolas, Rivenet, Murielle, Tougait, Olivier, Arab-Chapelet, Bénédicte, Venault, L., Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2018

15. Synthèse et caractérisation structurale des complexes à base de ligand peroxyde de plutonium

Author

Hibert, N., Rivenet, M., Tougait, O., Arab-Chapelet, B., Venault, L., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Caractérisation, Synthèse, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Peroxyde, Plutonium
Abstract

International audience; Dans le cadre de la transition technologique des réacteurs GEN III aux réacteurs GEN IV, lavoie de conversion du plutonium par peroxyde d’hydrogène représente une alternative intéressanteà la voie oxalique actuelle. La voie peroxyde permet une gestion simplifiée des effluents, l’absencede carbone résiduel dans les oxydes et une prise en charge des actinides U et Pu sans ajustementvalenciel. De plus, bénéficiant du retour d’expérience industriel de la conversion de l’uranium parvoie peroxyde, la co-conversion (U,Pu) par voie peroxyde représenterait un procédé innovantrépondant au cahier des charges des combustibles de génération IV de type RNR.Cependant, le développement d’un tel procédé de co-conversion repose sur la maîtrise de laconversion du plutonium qui est conditionnée par une connaissance complète et approfondie dusystème peroxyde-plutonium dont la chimie en solution, la chimie de coordination ainsi que lastabilité des espèces formées restent très peu documentées dans la littérature. L’objectif de cetteétude est donc d’acquérir des informations physico-chimiques sur les complexes de peroxyde deplutonium existants en solution et en phase solide mais aussi d’évaluer l’impact de la radiolyse surla structure des sels de peroxyde de plutonium.

Published
2018

16. Sonochemical Preparation and Characterization of Intrinsic Pu Colloids

Author

Dalodiere, E., Virot, M., Morosini, V., Chave, T., Dumas, T., Hennig, C., Wiss, T., Dieste Blanco, O., Shuh, D., Tyliszcak, T., Venault, L., Moisy, P., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Synchrotron Radiation Facility (ESRF), European Commission - Joint Research Centre [Geel] (JRC), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), and CADARACHE, Bibliothèque

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

19. Evidence for the Formation of a New Water Soluble Pu Peroxo Complex

Author

Virot, M., Dalodiere, E., Dumas, T., Tamain, C., Dieste Blanco, O., Wiss, T., Venault, L., Moisy, P., Nikitenko, Sergey I., CADARACHE, Bibliothèque, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Université Côte d'Azur, CEA Marcoule, CNRS, and ICN Nice

Subjects
raman, [PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], plutonium, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], ultrasons, peroxo, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS, sonochimie
Abstract

International audience

Published
2018

20. Radiolyse alpha du ligand DOTA en solution aqueuse

Author

Fiegel, V., Venault, L., Berthon, Laurence, CADARACHE, Bibliothèque, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

22. Pulse radiolysis study on the reactivity of NO3˙ radical toward uranous(IV), hydrazinium nitrate and hydroxyl ammonium nitrate at room temperature and at 45 °C.

Author

Musat, R., Marignier, J. L., Le Naour, C., Denisov, S., Venault, L., Moisy, Ph., and Mostafavi, M.

Abstract

Concentrated nitric acid solutions subjected to radiation produce radicals of extreme importance in the reprocessing of spent nuclear fuel. Knowledge of the different rate constants of the reactions involved in this chemistry is needed to improve the efficiency of the process and to define safe operating practices. Pulse radiolysis measurements are performed to find the rate constant of the reaction between NO3˙ radicals and U(IV) in highly concentrated nitrate solution. The optimal stabilization conditions toward thermal oxidation are defined for the considered solutions at room temperature and at 45 °C by adding anti-nitrous agents such as hydrazinium nitrate (HN) and hydroxyl ammonium nitrate (HAN). The decay of the NO3˙ radical is monitored and its reaction rates with HN, HAN and U(IV) are found to be 1.3 × 105, 1.5 × 107 and 1.6 × 106 M−1 s−1 at room temperature. The latter value is more than 10 times lower than the one currently used in numerical codes for simulation of the long-term radiolytic degradation associated with the reprocessing and storage of spent nuclear waste. At 45 °C, conditions similar to the reprocessing of spent fuel, the values of the rate constants of NO3˙ radical toward HN, HAN and U(IV) increase and are found to be 2.6 × 105, 2.9 × 107 and 9.3 × 106 M−1 s−1. [ABSTRACT FROM AUTHOR]

Published
2020
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23. Effect of carbon oxides on alpha-radiolysis of water sorbed on plutonium dioxide

Author

Venault, L., Vermeulen, J., Ringler, T., Moisy, P., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
sorbed water, [PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], carbon oxides, hydrogen, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Plutonium dioxide, alpha radiolysis
Abstract

International audience; Plutonium dioxide PuO2 is one of the main end-product in nuclear spent fuel reprocessing. This compound is classically stored in sealed containers under more or less moisty atmosphere before its reuse to manufacture new mixed-oxide (MOx) fuel. Plutonium dioxide is a very hygroscopic material and then the water molecules present in the moisty atmosphere are quickly adsorbed on plutonium dioxide surface [1-3]. This sorbed water then undergoes an a-radiolysis due to the plutonium radioactive decay. It has been showed that the decomposition of sorbed water on plutonium dioxide leads to the release of dihydrogen H2 [4-7]. Obviously, the kinetics of hydrogen evolution in the atmosphere depends on several physico-chemical parameters such as the specific surface area and isotopic composition of plutonium dioxide and the relative humidity of the atmosphere.However, the influence of the atmosphere above plutonium dioxide in the containers on dihydrogen generation has not been examined to a large extend. Most of the published data have been obtained under air or inert (Ar) atmosphere. Comparison of the data is not obvious and the effect of O2 and N2 on H2 formation is quite difficult to discern. In our experiments an increase in dihydrogen formation has sometimes been observed under an atmosphere of air compared to an Ar atmosphere, but the opposite effect, a decrease in hydrogen production, has happened too and unfortunately no clear conclusion can be drawn from these observations.Since carbon dioxide CO2 seems to be quickly and widely adsorbed on plutonium dioxide surface [8], it has then been decided to look at the effect of this gaseous compound on the kinetics of dihydrogen release in moisty atmospheres. The analysis has been extended to carbon monoxide and mixture of CO and CO2. The formation of dihydrogen as well as the consumption of carbon oxides has been followed using gas chromatography. The carbon oxides were introduced in the experiment cells at a level amount of 5-10 vol. percent as a mixture with Argon and the relative humidity is kept constant in the cells. It has been observed that the amount of produced dihydrogen slightly increases in the presence of CO2 in comparison of what have been measured under pure argon. In the same time, no measurable consumption of CO2 has been detected. Dihydrogen formation is significantly enhanced in the presence of CO, this latter being oxidized as CO2. The formation of H2 under an atmosphere containing both CO and CO2 is particular: in a first step, the formation of H2 is lowered and in a second step it looks like the one observed in the presence of CO only. Mechanisms have been postulated to account for these phenomena.

Published
2017

24. Radiolytic decomposition of zinc stearate in presence of PuO$_2$ powders

Author

Gracia, J., Venault, L., Vermeulen, J., Guigue, M., Maurin, J., Audubert, F., Colin, Xavier, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Procédés et Ingénierie en Mécanique et Matériaux [Paris] (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-École Nationale Supérieure d'Arts et Métiers (ENSAM), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-Centre National de la Recherche Scientifique (CNRS), Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre National de la Recherche Scientifique (CNRS)-Arts et Métiers Sciences et Technologies, HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), and amplexor, amplexor

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], Decomposition, Zinc, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Radiolytic, Presence, PuO$_2$, Powders, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Stearate, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016

25. Radiolyse α des solutions aqueuses d’acide nitrique et de plutonium

Author

Venault, L., Garaix, G., Vandenborre, Johan, Moisy, P., Département RadioChimie et Procédés (DRCP), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire SUBATECH Nantes (SUBATECH), and Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2016

26. Structural investigation of Pd(II) in concentrated nitric and perchloric acid solutions by XAFS

Author

Purans, J., Fourest, B., Cannes, C., Sladkov, V., David F., Venault, L., and Lecomte, M.

Subjects
Nitric acid -- Chemical properties, Palladium -- Chemical properties, Palladium -- Structure, Chemicals, plastics and rubber industries
Abstract

XAFS spectra of palladium(II) in concentrated HNO3/HClO4 acid mixtures are recorded and analyzed. The study confirmed the formation of Pd-nitrate complexes in concentrated HNO3 solutions.

Published
2005

27. Preparation and characterization of intrinsic plutonium colloids by sonolysis of puo2 in water

Author

Dalodiere, E., Virot, M., Morosini, V., Chave, T., Dumas, T., Hennig, C., Wiss, T., Dieste Blanco, O., Shuh, D., Tyliszcak, T., Venault, L., Moisy, P., Nikitenko S, I., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Advanced Light Source [LBNL Berkeley] (ALS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016

28. Sonochemistry of plutonium

Author

Virot, M., Chave, T., Dalodiere, E., Beaudoux, X., Morosini, V., Dumas, T., Leturcq, G., Venault, L., Moisy, P., Nikitenko, S.-I., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS, Plutonium, Sonochemistry
Abstract

International audience

Published
2016

29. Sonochemistry of Actinides

Author

Virot, Matthieu, CHAVE, Tony, Morosini, V., Pflieger, R., Nikitenko, Sergey I., Venault, L., Moisy, Philippe, Le Goff, Xavier, Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM] Chemical Sciences, [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016

31. Behavior under alpha irradiation of butanal oxime, a potential substitue to hydrazinium nitrate in the PUREX process

Author

Costagliola, A., Venault, L., Deroche, A., Blain, G., Vandenborre, J., Fattahi-Vanani, M., Vigier, N., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and CEA-Direction de l'Energie Nucléaire (CEA-DEN)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Alpha radiolysis, PUREX process, hydrogen, hydrazinium nitrate, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS, butanal oxime
Abstract

International audience

Published
2015

32. Alpha radiolysis of nitric acid using the 68 MeV helions beam of the ARRONAX cyclotron

Author

Garaix, G., Venault, L., Maurin, J., Costagliola, A., Vandenborre, J., Fattahi, M., Vigier, N., Moisy, P., CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), and Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Alpha radiolysis, Nitrous acid, ARRONAX cyclotron, Nitric acid, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Hydrogen peroxyde, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

33. Overview of the french Radiation Chemistry studies and Radiolytic degradation of Monoamides

Author

Charbonnel, M.-C., Berthon, Laurence, Cames, B., Venault, L., Peuget, S., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CEA-Direction de l'Energie Nucléaire (CEA-DEN), and amplexor, amplexor

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], radiolysis, molecules, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS, degradation
Abstract

International audience

Published
2015

34. Comportement sous rayonnement alpha de la butyraldoxime, un substituant potentiel à l'hydrazine dans le procédé PUREX

Author

Costagliola, A., Venault, L., Fattahi, M., CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CIC - Nantes, Université de Nantes (UN)-IFR26-Institut National de la Santé et de la Recherche Médicale (INSERM), and CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN))

Subjects
Butyraldoxime, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Acide nitreux, Retraitement du combustible nucléaire, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Radiolyse, Irradiation alpha
Abstract

National audience; Cette étude concerne le comportement sous rayonnement alpha de la butyraldoxime, un substituant potentiel au nitrate d'hydrazinium lors du retraitement du combustible nucléaire irradié, et plus précisément lors de la phase de séparation uranium-plutonium. La méthode expérimentale employée pour étudier la radiolyse de ce composé est dans un premier temps détaillée autour d'un exemple, la production de peroxyde d'hydrogène. Puis, quelques résultats concernant la stabilité de la molécule et la formation de produits gazeux et de produits en phase liquide sont présentés.

Published
2015

35. Radiation chemical behavior of aqueous butanal oxime solutions under alpha irradiation

Author

Costagliola, A., Venault, L., Garaix, G., Blain, G., Vandenborre, Johan, Vigier, N., De Sio, S., Fattahi-Vanani, M., CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), AREVA NC, Groupe AREVA, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), and Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Radiolysis, nuclear fuel reprocessing, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nitrous acid, Alpha irradiation, butanal oxime
Abstract

International audience; Context Hydrazinium nitrate is a compound used in industry to avoid nitrous acid accumulation during the liquid-liquid separation of uranium and plutonium (PUREX). Now, hydrazinium nitrate is a CMR (Carcinogenic, Mutagenic, or toxic to Reproduction) compound and its use has to be reduced according to the European REACH directive of 2007. Moreover, hydrazinium nitrate is not extracted in the organic phase. Then it induces an accumulation of nitrous acid in this medium due to its partition between the two phases. It leads to an over-consumption of the Pu reducer, U(IV), due to the reoxidation of plutonium (III) to plutonium (IV) by HNO$_2$ in the organic phase. Numerous substitutes to hydrazinium nitrate have then been considered to find a compound which quickly reacts with HNO$_2$ and which can be partly extracted by TBP. The aim of this study is actually to investigate the behavior of these potential substitutes under irradiation. As a result of previous investigations, butanal oxime has been selected as potential substitute to hydrazinium nitrate in the PUREX process.

Published
2015

36. Insights into the sonochemical synthesis and properties of salt-free intrinsic plutonium colloids

Author

Dalodière, E., Virot, M., Morosini, V., Chave, T., Dumas, T., Hennig, C., Wiss, T., Blanco, O. D., Shuh, D. K., Tyliszcak, T., Venault, L., Moisy, P., Nikitenko, S. I., Dalodière, E., Virot, M., Morosini, V., Chave, T., Dumas, T., Hennig, C., Wiss, T., Blanco, O. D., Shuh, D. K., Tyliszcak, T., Venault, L., Moisy, P., and Nikitenko, S. I.

Abstract

For the first time, stable intrinsic plutonium colloid was prepared by ultrasonic treatment of PuO2 suspensions in pure water at room temperature. The yield of Pu colloid was found to increase with PuO2 specific surface area and by using reducing carrier gas mixture. Kinetic data evidenced that both chemical and mechanical effects of ultrasound strongly contribute to the mechanism of Pu colloid formation. At first, the fragmentation of initial PuO2 particles accelerates the overall process providing larger surface of contact between cavitation bubbles and solids. Furthermore, hydrogen formed during sonochemical water splitting enables reduction of Pu(IV) to more soluble Pu(III), which then reoxidizes yielding Pu(IV) colloid. Sonochemical colloid was compared with hydrolytic one using HRTEM, Pu LIII XAS, and STXM/NEXAFS (O K-edge) techniques. Both colloids are composed of quasi-spherical nanocrystalline particles of PuO2 (fcc, Fm¯3 m space group) measuring about 7 nm and 3 nm, respectively. Moreover, HRTEM revealed nanostructured morphology for initial PuO2. The EXAFS spectra of colloidal PuO2 nanoparticles were fitted using triple oxygen shell model for the first coordination sphere of Pu(IV). HRTEM and EXAFS studies revealed the correlation between the number of Pu-O and Pu-Pu contacts and atomic surface-to-volume ratio of studied PuO2 nanoparticles. The STXM/NEXAFS study indicated that the oxygen state of hydrolytic Pu colloid is influenced by hydrolyzed Pu(IV) species in much more extent than PuO2 nanoparticles of sonochemical colloid. In general, hydrolytic and sonochemical colloids can be described as core-shell nanoparticles composed of quasi stoichiometric PuO2 core and hydrolyzed Pu(IV) moieties at the surface shell.

Published
2017

37. Radiolytic stability of aqueous solutions of butanal oxime under alpha irradiation

Author

Costagliola, A., Vigier, N., Venault, L., Deroche, A., Blain, G., Vandenborre, Johan, Fattahi-Vanani, M., Omnee, R., Sauvage, Th., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes)

Subjects
Oxime, [PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Alpha radiolysis, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], hydrogen, hydrogen peroxide, Nitric acid, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nitrous acid, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

38. Alpha radiolysis induced by plutonium dioxide

Author

Venault, L., Moisy, P., Dannoux-Papin, A., Poulesquen, A., Audubert, F., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], hydrogen, Radiolysis, plutonium dioxide, nuclear fuel, waste, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; Up to now, plutonium dioxide is the major end product of nuclear fuel reprocessing. Due to the radioactive properties of plutonium, handling and management both of plutonium dioxide and of contaminated wastes involve to take into account the radiolysis phenomena plutonium can induce. For instance, plutonium is known to be a highly hygroscopic compound. Kept under a humid atmosphere, up to 3% wt. water can be sorbed on the surface of plutonium dioxide. The sorbed water then is going to undergo a radiolytic decomposition and this latter will lead to hydrogen evolution. It has been shown through our studies and other reported results that hydrogen formation kinetic depends on the specific surface area of plutonium dioxide, the isotopic composition of plutonium and the relative humidity in the atmosphere. Unfortunately no clear dependences between the rate of hydrogen formation and these parameters can be established. However, it has been shown that in many cases hydrogen amount in the atmosphere reaches a steady-state. Such behaviour is probably linked to surface evolution of plutonium dioxide in presence of moist air and under radiolytic decomposition of water. Studies are still in progress to identify surface changes due to these phenomena. Hydrogen can be produced under radiolysis of some plastic waste contaminated by plutonium dioxide too. Whereas $\gamma$-radiolysis of plastic materials is quite well described, $\alpha$-radiolysis of such compounds, especially the ones in close contact with actinides, is very poorly known. It can be demonstrated that only a small part of the whole energy emitted by plutonium dioxide is going to be deposited in the material and leads to a radiolytic decomposition with hydrogen and others hazardous gaseous products (CH$_4$ for instance) formation. Taking into account the amount of energy transferred to the plastic material, $\alpha$-radiolytic yield of hydrogen can be calculated and then used for waste repository scale-up. It should be noticed that plutonium dioxide can exhibit specific behaviour towards some radiolytic products. For instance, it has been shown that chlorine arising from PVC radiolytic decomposition is going to be retained mainly on plutonium dioxide surface, whereas without plutonium dioxide chlorine is evolved as gaseous HCl. In the same way, $\alpha$-radiolysis induced by plutonium dioxide on several other materials is now studied, such as hydrogen, carbon oxides and short-length alkane production from some lubricating compounds used in fuel pellet manufacturing or from specific waste embedding materials (bitumen, mineral polymers). As the present trend is still to increase fuel burn-up in one hand, and, in the other hand to manufacture new fuel with increasing amount of plutonium, it appears necessary to look closer at the radiolytic phenomena induced by actinide oxide and especially plutonium dioxide to actualize the safety analysis for handling and management of future nuclear fuels and wastes.

Published
2015

39. Redox Reactions of Pu ions in Aqueous Nitric Solutions under Ultrasound Irradiation

Author

Matthieu Virot, Venault, L., Moisy, P., Nikitenko, S. I., Sonochimie dans les Fluides Complexes (LSFC), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physico-Chimie des Procédés (LPCP), CADARACHE, Bibliothèque, and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; In France, industrial reprocessing of spent nuclear fuel involves the dissolution of the irradiated fuel in concentrated nitric media in view of the recycling and separation of uranium and plutonium. Among others, the current treatment of spent fuel raises the questions of waste and effluent management. With the aim of preparing future GENIV reactors and answering to the world demand in the development of a more sustainable nuclear energy, new alternatives are nowadays investigated. Sonochemistry, which studies the influence of ultrasonic waves on chemical systems, has been showed to enhance chemical yields and accelerate reaction rates for several homogeneous and heterogeneous systems. The aim of the present study is to evaluate the potential of high-power ultrasound towards the control and stabilization of Pu oxidation states in aqueous nitric solution.

Published
2014

40. Transporting radioactive samples from the laboratory to the ESRF

Author

Venault, L., Den Auwer, C., Moisy, P., Colomp, P., Scheinost, A. C., and Hennig, C.

Subjects
EXAFS, actinides, XANES, radionuclides, The Rossendorf beamline
Abstract

Desription of safety efforts required to transport radioactive samples

Published
2010

47. Coprecipitation of actinide peroxide salts in the U-Th and U-Pu systems and their thermal decomposition.

Author

Hibert N, Arab-Chapelet B, Rivenet M, Venault L, Tamain C, and Tougait O

Abstract

The uranium and plutonium co-conversion process constitutes a continuous subject of interest for MOx fuel fabrication. Among the various routes considered, chemical coprecipitation by the salt effect has been widely investigated regarding its simplicity of integration between the partitioning and purification steps of the PUREX process, and the straightforward recovery of precursors that are easily converted into oxide phases by thermal decomposition. The present study focuses on the coprecipitation behavior of U-Th and U-Pu actinide peroxide mixed systems by examining the precipitation yields and settling properties for nitric acidity in the range of 1 to 3 M and hydrogen peroxide concentration in the range of 4.5 to 7 M. The precipitated solids have been characterized by powder XRD, IR and Raman spectroscopy, laser granulometry and SEM-EDS analyses revealing the synthesis of studtite and actinide(IV) peroxo-nitrates as aggregated particles. The actinide solid phases are uniformly distributed within the filtered cakes. The precursor thermal decomposition results in the formation of oxide phases at low temperature according to a sequential release of water molecules, peroxide ligands and nitrate ions. The calcination step has a limited effect on the morphology of the powders which remain highly divided. The high precipitation rate of actinides makes this chemical route potentially interesting as a co-precipitation process.

Published
2022
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48. Pulse radiolysis study on the reactivity of NO 3 ˙ radical toward uranous(iv), hydrazinium nitrate and hydroxyl ammonium nitrate at room temperature and at 45 °C.

Author

Musat R, Marignier JL, Le Naour C, Denisov S, Venault L, Moisy P, and Mostafavi M

Abstract

Concentrated nitric acid solutions subjected to radiation produce radicals of extreme importance in the reprocessing of spent nuclear fuel. Knowledge of the different rate constants of the reactions involved in this chemistry is needed to improve the efficiency of the process and to define safe operating practices. Pulse radiolysis measurements are performed to find the rate constant of the reaction between NO3˙ radicals and U(iv) in highly concentrated nitrate solution. The optimal stabilization conditions toward thermal oxidation are defined for the considered solutions at room temperature and at 45 °C by adding anti-nitrous agents such as hydrazinium nitrate (HN) and hydroxyl ammonium nitrate (HAN). The decay of the NO3˙ radical is monitored and its reaction rates with HN, HAN and U(iv) are found to be 1.3 × 105, 1.5 × 107 and 1.6 × 106 M-1 s-1 at room temperature. The latter value is more than 10 times lower than the one currently used in numerical codes for simulation of the long-term radiolytic degradation associated with the reprocessing and storage of spent nuclear waste. At 45 °C, conditions similar to the reprocessing of spent fuel, the values of the rate constants of NO3˙ radical toward HN, HAN and U(iv) increase and are found to be 2.6 × 105, 2.9 × 107 and 9.3 × 106 M-1 s-1.

Published
2020
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49. Probing the local structure of nanoscale actinide oxides: a comparison between PuO 2 and ThO 2 nanoparticles rules out PuO 2+ x hypothesis.

Author

Bonato L, Virot M, Dumas T, Mesbah A, Dalodière E, Dieste Blanco O, Wiss T, Le Goff X, Odorico M, Prieur D, Rossberg A, Venault L, Dacheux N, Moisy P, and Nikitenko SI

Abstract

Actinide research at the nanoscale is gaining fundamental interest due to environmental and industrial issues. The knowledge of the local structure and speciation of actinide nanoparticles, which possibly exhibit specific physico-chemical properties in comparison to bulk materials, would help in a better and reliable description of their behaviour and reactivity. Herein, the synthesis and relevant characterization of PuO 2 and ThO 2 nanoparticles displayed as dispersed colloids, nanopowders, or nanostructured oxide powders allow to establish a clear relationship between the size of the nanocrystals constituting these oxides and their corresponding An(iv) local structure investigated by EXAFS spectroscopy. Particularly, the first oxygen shell of the probed An(iv) evidences an analogous behaviour for both Pu and Th oxides. This observation suggests that the often observed and controversial splitting of the Pu-O shell on the Fourier transformed EXAFS signal of the PuO 2 samples is attributed to a local structural disorder driven by a nanoparticle surface effect rather than to the presence of PuO 2+ x species., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Published
2019
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50. Insights into the sonochemical synthesis and properties of salt-free intrinsic plutonium colloids.

Author

Dalodière E, Virot M, Morosini V, Chave T, Dumas T, Hennig C, Wiss T, Dieste Blanco O, Shuh DK, Tyliszcak T, Venault L, Moisy P, and Nikitenko SI

Abstract

Fundamental knowledge on intrinsic plutonium colloids is important for the prediction of plutonium behaviour in the geosphere and in engineered systems. The first synthetic route to obtain salt-free intrinsic plutonium colloids by ultrasonic treatment of PuO 2 suspensions in pure water is reported. Kinetics showed that both chemical and mechanical effects of ultrasound contribute to the mechanism of Pu colloid formation. In the first stage, fragmentation of initial PuO 2 particles provides larger surface contact between cavitation bubbles and solids. Furthermore, hydrogen formed during sonochemical water splitting enables reduction of Pu(IV) to more soluble Pu(III), which then re-oxidizes yielding Pu(IV) colloid. A comparative study of nanostructured PuO 2 and Pu colloids produced by sonochemical and hydrolytic methods, has been conducted using HRTEM, Pu L III -edge XAS, and O K-edge NEXAFS/STXM. Characterization of Pu colloids revealed a correlation between the number of Pu-O and Pu-Pu contacts and the atomic surface-to-volume ratio of the PuO 2 nanoparticles. NEXAFS indicated that oxygen state in hydrolytic Pu colloid is influenced by hydrolysed Pu(IV) species to a greater extent than in sonochemical PuO 2 nanoparticles. In general, hydrolytic and sonochemical Pu colloids can be described as core-shell nanoparticles composed of quasi-stoichiometric PuO 2 cores and hydrolyzed Pu(IV) moieties at the surface shell.

Published
2017
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