Separation for Transmutation - Why and How? Today only a small fraction of the energy in nuclear fuel is used. The spent fuel also has to be stored for about years to be considered safe. The extremely long storage time is mainly due to the high radiotoxicity of the actinides. If, however, these long lived actinides could be separated from the spent fuel and transmuted, the energy efficiency would increase. In addition, the storage time could be shortened to about 1000 years and the volume of waste in need of long time storage would be heavily decreased. This way the spent fuel could be considered a resource instead of just waste. One way to achieve this separation is by liquid –liquid extraction. This is a method that has been used to e.g. separate plutonium and uranium from dissolved spent nuclear fuel since the 50:ies (PUREX process). Great efforts have in the recent 20 years been put into research for developing this method to be able to achieve the complicated task of separation for transmutation. Separation for Transmutation - Why and How? Today only a small fraction of the energy in nuclear fuel is used. The spent fuel also has to be stored for about years to be considered safe. The extremely long storage time is mainly due to the high radiotoxicity of the actinides. If, however, these long lived actinides could be separated from the spent fuel and transmuted, the energy efficiency would increase. In addition, the storage time could be shortened to about 1000 years and the volume of waste in need of long time storage would be heavily decreased. This way the spent fuel could be considered a resource instead of just waste. One way to achieve this separation is by liquid –liquid extraction. This is a method that has been used to e.g. separate plutonium and uranium from dissolved spent nuclear fuel since the 50:ies (PUREX process). Great efforts have in the recent 20 years been put into research for developing this method to be able to achieve the complicated task of separation for transmutation. Nuclear Chemistry and Industrial Materials Recycling at Chalmers The research groups of Nuclear Chemistry and Industrial Materials Recycling are parts of the Department of Chemical and Biological Engineering at Chalmers. Together, the two groups consist of ten senior researchers (professors, assistant professors and doctors), two professor emeritus, ten doctoral students and a varying number of diploma workers as well as technical and administrative staff, with the major part related to Nuclear Chemistry. The work carried out at Nuclear Chemistry today ranges over many different areas in the field of nuclear chemistry e.g. complexation chemistry, medical applications, super heavy elements, severe nuclear accidents, fundamental liquid-liquid extraction, actinide chemistry, radio analytical chemistry and separation & transmutation. The Nuclear Chemistry group at Chalmers has almost 50 years of experience in liquid-liquid extraction and was one of the first institutes to investigate basic properties of extraction systems. 25 years ago a group at Nuclear Chemistry for the first time studied separation and transmutation as means to reduce the radiotoxicity of waste from processing plants. This research started again 13 years ago as part of an EU project, NEWPART, followed by PARTNEW and then EUROPART. The fourth EU framework project in the area of separation and transmutation, ACSEPT, has been running since March 2008 and the Chalmers group is participating. Nuclear Chemistry and Industrial Materials Recycling at Chalmers The research groups of Nuclear Chemistry and Industrial Materials Recycling are parts of the Department of Chemical and Biological Engineering at Chalmers. Together, the two groups consist of ten senior researchers (professors, assistant professors and doctors), two professor emeritus, ten doctoral students and a varying number of diploma workers as well as technical and administrative staff, with the major part related to Nuclear Chemistry. The work carried out at Nuclear Chemistry today ranges over many different areas in the field of nuclear chemistry e.g. complexation chemistry, medical applications, super heavy elements, severe nuclear accidents, fundamental liquid-liquid extraction, actinide chemistry, radio analytical chemistry and separation & transmutation. The Nuclear Chemistry group at Chalmers has almost 50 years of experience in liquid-liquid extraction and was one of the first institutes to investigate basic properties of extraction systems. 25 years ago a group at Nuclear Chemistry for the first time studied separation and transmutation as means to reduce the radiotoxicity of waste from processing plants. This research started again 13 years ago as part of an EU project, NEWPART, followed by PARTNEW and then EUROPART. The fourth EU framework project in the area of separation and transmutation, ACSEPT, has been running since March 2008 and the Chalmers group is participating. Emma Aneheim 1,2, Christian Ekberg 2, Sofie Englund 3, Anna Fermvik 1,2, Jan-Olov Liljenzin 1, Elin Löfström-Engdahl 1,2 Mikael Nilsson 4, Teodora Retegan 1, Gunnar Skarnemark 1 1 Nuclear Chemistry, 2 Industrial Materials Recycling - Department of Chemical and Biological Engineering, Chalmers University of Technology, Kemivägen 4, SE Gothenburg, Sweden. 3 OKG, AB, SE , Oskarshamn, Sweden, 4 University of California – Irvine, USA Separation for Transmutation at Chalmers What is liquid-liquid extraction? Liquid–liquid extraction is a process where different species, e.g. metal ions, are transferred from an aqueous phase to an organic phase. If the aqueous phase contains several different metal ions there is a possibility to separate them from each other by e.g. the use of different extracting molecules in the organic phase. After the extraction some ions are left in the aqueous phase while others are transferred to the organic phase. What is liquid-liquid extraction? Liquid–liquid extraction is a process where different species, e.g. metal ions, are transferred from an aqueous phase to an organic phase. If the aqueous phase contains several different metal ions there is a possibility to separate them from each other by e.g. the use of different extracting molecules in the organic phase. After the extraction some ions are left in the aqueous phase while others are transferred to the organic phase. Aqueous phase: Lanthanides + FP Actinides (In nitric acid) Organic phase: Extractant + Diluent Mixing Separation Separation for Transmutation at Nuclear Chemistry At Nuclear Chemistry almost all aspects of the separation research is taking place, from the first idea to the finished pilot scale process. Design and synthesis of extracting molecules The primary task of the extractant molecules is to separate actinides from lanthanides, which have very similar chemical properties. Screening of new extractants Some basic properties have to be investigated to determine whether or not further studies of the new extractant should be performed. Detailed extraction experiments E.g. how irradiation of the extractant affects the extraction of different metals. The radiation behaviour is relevant due to the high levels of radioactivity that would be present in an industrial application with real spent nuclear fuel. System optimization & Process design Studies regarding e.g. the influence of different diluents and the kinetics of the system. Development from lab scale towards an industrial process. Separation for Transmutation at Nuclear Chemistry At Nuclear Chemistry almost all aspects of the separation research is taking place, from the first idea to the finished pilot scale process. Design and synthesis of extracting molecules The primary task of the extractant molecules is to separate actinides from lanthanides, which have very similar chemical properties. Screening of new extractants Some basic properties have to be investigated to determine whether or not further studies of the new extractant should be performed. Detailed extraction experiments E.g. how irradiation of the extractant affects the extraction of different metals. The radiation behaviour is relevant due to the high levels of radioactivity that would be present in an industrial application with real spent nuclear fuel. System optimization & Process design Studies regarding e.g. the influence of different diluents and the kinetics of the system. Development from lab scale towards an industrial process. This work was supported by the Swedish Nuclear Fuel and Waste Management Co., SKB and the European Union Framework Program ACSEPT.