[en] Faced with the new options for the high level waste management, the ''Partitioning and Transmutation (P and T)'' of the radio nuclides contained in the irradiated nuclear fuel appear as a promising option from different points of view, such as environmental risk, radiotoxic inventory reduction, economic, etc.. The present work is part of a research project called ''PYROREP'' of the 5th FWP of the EU that studied the feasibility of the actinide separation from the rest of fission products contained in the irradiated nuclear fuel by pyrometallurgical processes with the aim of their transmutation. In order to design these processes it is necessary to determine basic thermodynamic and kinetic data of the radionuclides contained in the nuclear fuel in molten salt media. The electrochemical study of uranium, samarium and molybdenum in the eutectic melt LiCl - KCl has been performed at a tungsten electrode in the temperature range of 450 - 600 deg C in order to obtain these basic properties. (Author)

[en] Actinide recycling by separation and transmutation is considered world wide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste, thus contributing to making nuclear energy sustainable. By joining together European universities, nuclear research bodies and major industrial players in a multi-disciplinary consortium, the FP7 EURATOM Fission Project ACSEPT provides the sound basis and fundamental improvements for future demonstrations of fuel treatment in strong connection with fuel fabrication techniques. In accordance with the Strategic Research Agenda of the Sustainable Nuclear Energy Technology Platform (SNE-TP), the timelines of this four-year R and D project (2008-2012) should allow the offering of technical solutions in terms of separation process that may be reviewed by governments, European utilities as well as technology providers at that time horizon. By showing a technically feasible recycling of actinides strategy, ACSEPT will certainly produce positive arguments in the sense that European decision makers, and more globally public opinion, could be convinced that technical solutions for a better management of nuclear wastes are now technologically feasible. ACSEPT is thus an essential contribution to the demonstration, in the long term, of the potential benefits of actinide recycling to minimise the burden on geological repositories. To succeed, ACSEPT is organised in three technical domains: i) Considering technically mature aqueous separation processes, ACSEPT will optimise and select the most promising ones dedicated either to actinide partitioning or to group actinide separation. These developments are appropriately balanced with an exploratory research focused on the design of new molecules. ii) Concerning pyrochemical separation processes, ACSEPT first focuses on the enhancement of the two reference cores of process selected within EUROPART. R and D efforts shall also be brought to key scientific and technical points compulsory for building a whole separation process. iii) All experimental results will be integrated by carrying out engineering and systems studies on hydro- and pyro-processes to prepare for future demonstration at a pilot level. In parallel, with a view to consolidate future actinide recycling strategies, ACSEPT is in charge of the design of the minor-actinide-containing pins, prior to their fabrication in the future FAIRFUELS FP7 project. A training and education programme is also being implemented to share the knowledge within the partitioning community and present and future generations of researchers. Specific attention will be given to the funding of multi-partite post-doctorate fellowships. (authors)

[en] Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste, thus contributing to the sustainability of nuclear energy. Consistently with potentially viable recycling strategies, the Collaborative Project ACSEPT will provide a structured research and development framework to develop chemical separation processes compatible with fuel fabrication techniques, with a view to their future demonstration at the pilot level. Two strategies are proposed for the recycling of the actinides issuing from various forms of future nuclear fuels: -) their homogeneous recycling in mixed fuels via a prior group separation of the actinides and -) their heterogeneous recycling in targets or core blankets via their selective separation from fission products. Two major technologies are considered to meet these challenges: hydrometallurgical processes and pyrochemical processes. A training and education programme will also be implemented to share the knowledge among communities and generations so as to maintain the nuclear expertise at the fore-front of Europe. The challenging objectives of ACSEPT will be addressed by a multi-disciplinary consortium composed of European universities, nuclear research bodies and major industrial players. This consortium will generate fundamental improvements for the future design of a potential Advanced Processing Pilot Unit

[en] Actinide recycling by partitioning and transmutation is considered as one of the most promising strategies to reduce the inventory of radioactive waste, thus contributing to make nuclear energy sustainable. To make advances beyond the current state of the art in pyrochemical separations processes, the Domain 2 (DM2) of ACSEPT has been built on considering a process approach based on system studied. Four work packages that represent the main steps of a process block diagram have been identified: head-end steps, core process development, and salt treatment for recycling and waste conditioning. The results obtained in this domain will be integrated in DM 3 (Process) in order to orientate the R and D studies of DM2 and to propose and validate flowsheets at the end of the project. The state of the art on pyrochemical separation within the European Community and the working program of ACSEPT in pyrometallurgy are presented in this work. (authors)

[en] Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimize the use of natural resources, thus contributing to making nuclear energy sustainable. In accordance with the Strategic Research Agenda (SRA) of the Sustainable Nuclear Energy Technology Platform (SNE-TP), the timelines of the FP7-EURATOM project ACSEPT (2008-2012) should allow the offering of technical solutions in terms of advanced closed fuel cycle technologies including the recycling of actinides and that may be reviewed by Governments, European utilities as well as Technology Providers at the time horizon 2012. By joining in its consortium 34 partners from 12 European countries plus Australia and Japan, ACSEPT is thus an essential contribution to the demonstration, in the long term, of the potential benefits of actinide recycling. To succeed, ACSEPT is organized into three technical domains: (i) Considering technically mature aqueous separation processes, ACSEPT works to optimize and select the most promising ones dedicated either to actinide partitioning or to grouped actinide separation. A substantial review was undertaken either to be sure that the right molecule families are being studied, or, on the contrary, to identify new candidates. After 18 months, results of the first hot tests should allow the validation of some process options. In addition, the first results on dissolution studies will be available as well as the progress in conversion techniques. (ii) Concerning pyrochemical separation processes, ACSEPT is focused on the enhancement of the two reference cores of process selected within EUROPART with specific attention to the exhaustive electrolysis in molten chloride (quantitative recovery of the actinides with the lowest amount of fission products) and to actinide back-extraction from an An-Al alloy. R and D efforts are also brought to key scientific and technical issues compulsory for building a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii) By integrating all the experimental results within engineering and systems studies, both in hydro and pyro domains, ACSEPT will therefore deliver relevant flowsheets and recommendations to prepare for future demonstration at a pilot level, in relation with strategies developed through the SNE-TP. In addition, a training and education programme is implemented to share the knowledge among the partitioning community, and present and future generations of researchers. Specific attention is given to the funding of post-doctorate fellowships, the first one having been appointed at the end of 2008. (authors)

[en] Document in abstract form only. Full text of publication follows: Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimise the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project 'Actinide Recycling by Separation and Transmutation' (ACSEPT) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes. To succeed, ACSEPT is organised into three technical domains: i) Considering technically mature aqueous separation processes, ACSEPT works to optimise and select the most promising ones dedicated either to actinide partitioning (for the heterogeneous recycling of actinides in ADS target or specific actinide-bearing blanket fuels in fast reactor) or to grouped actinide separation (for the homogeneous recycling of actinides in fast reactor fuels). In addition, dissolution and conversion studies are under way by taking into account the specific requirements of these different fuels. ii) Concerning pyrochemical separation processes, ACSEPT is focused on the enhancement of the two reference cores of process selected within EUROPART with specific attention to exhaustive electrolysis in molten chloride (quantitative recovery of the actinides with the lowest amount of fission products) and to actinide back-extraction from an An-Al alloy. R and D efforts are also brought to key scientific and technical issues compulsory for building a complete separation process (head-end steps, salt treatment for recycling and waste management). iii) By integrating all the experimental results within engineering and system studies, both in hydro and pyro domains, ACSEPT will therefore deliver relevant flow sheets and recommendations to prepare for future demonstrations at a pilot level. After more than two years of work, significant progress has been achieved in process development with the demonstration of SANEX and innovative SANEX flow sheets. Chemical systems were selected for GANEX and are under study. In pyrometallurgy, the work progresses as well. In addition, efforts were made to increase collaborations, mutualise and homogenise procedures and share good practices. Based on these assessments, it is then time to look at the future challenges to be issued. A training and education programme is implemented to share knowledge among the partitioning community, and present and future generations of researchers. Specific attention is also given to the funding of post-doctorate fellowships, two having been appointed respectively at the end of 2008 and at the end of 2009. Through this training and education programme, the first ACSEPT International Workshop was organised last March in Lisbon, Portugal. It placed an emphasis on students' contributions (two-thirds of the presentations) and allowed young scientists to meet and exchange with internationally recognised experts. (authors)

[en] Plutonium trichloride solution in the molten LiCl-KCl eutectic was prepared by carbochlorination of plutonium oxide. Kinetics of this reaction was compared in different conditions in the range of 443-550 deg. C. Using this molten salt solution, the redox potential of the Pu(III)/Pu couple at inert tungsten electrode was measured at 450 deg. C by electromotive force measurement and was found to be E'^o = -2.76 V vs. the Cl_2(g)(1 atm)/Cl^- reference electrode (molar fraction scale). Reaction between plutonium trichloride and oxide ions was studied by potentiometric titration, using yttria stabilized electrodes. In our experimental conditions, the titration curves indicate the precipitation of the sesquioxide Pu₂O₃. The solubility product cologarithm calculated from these curves is found to be pK_s(Pu₂O₃) = 22.8 ± 1.1 (molality scale). Using the experimentally obtained values for E'^o, activity coefficient and pK_s joined to the published thermodynamic data, the stability phase diagram of the Pu-O species was then drawn