tailieunhanh - Formalization of the kinetics for autocatalytic dissolutions. Focus on the dissolution of uranium dioxide in nitric medium

In this work, the kinetics rates have been measured by optical microscopy using a single particle approach. The advantages of this analytical technique are an easier management of species transport in solution and a precise following of the dissolution rate. | Formalization of the kinetics for autocatalytic dissolutions. Focus on the dissolution of uranium dioxide in nitric medium EPJ Nuclear Sci. Technol. 3 26 2017 Nuclear Sciences F. Charlier et al. published by EDP Sciences 2017 amp Technologies DOI epjn 2017018 Available online at http REGULAR ARTICLE Formalization of the kinetics for autocatalytic dissolutions. Focus on the dissolution of uranium dioxide in nitric medium Florence Charlier1 Delphine Canion1 Anthony Gravinese1 Alastair Magnaldo1 Sophie Lalleman1 Gilles Borda2 and Éric Schaer3 1 CEA Nuclear Energy Division Research Department of Mining and Fuel Recycling Processes Service of Dissolution and Separation Processes Laboratory of Dissolution Studies 30207 Bagnols-sur-Cèze France 2 CEA Nuclear Energy Division Research Department of Mining and Fuel Recycling Processes SA2I Laboratory of Chemical Engineering and Instrumentation 30207 Bagnols-sur-Cèze France 3 Laboratory of Reaction and Process Engineering UMR7274 CNRS Université De Lorraine 54001 Nancy France Received 1 February 2017 Received in final form 5 July 2017 Accepted 17 July 2017 Abstract. Uranium dioxide dissolution in nitric acid is a complex reaction. On the one hand the dissolution produces nitrous oxides NOX which makes it a triphasic reaction. On the other hand one of the products accelerates the kinetic rate the reaction is hence called autocatalytic. The kinetics for these kinds of reactions need to be formalized in order to optimize and design innovative dissolution reactors. In this work the kinetics rates have been measured by optical microscopy using a single particle approach. The advantages of this analytical technique are an easier management of species transport in solution and a precise following of the dissolution rate. The global rate is well described by a mechanism considering two steps a non-catalyzed reaction where the catalyst concentration has no influence on the dissolution rate and a catalyzed .