From the Bataille's Law to the Am-recycling integral experiments, overview of 25 years of RandD in CEA on Minor Actinides Partitioning Processes
Résumé
In Dec.1991, French Parliament voted the first French waste management Act which among others, requests the launching of a large RetD program to study the potential partitioning and transmutation of long-lived radionuclides (LLRN) in order to decrease the waste long-term toxicity and volume. Indeed, LLRN transmutation was thought to be able to reduce the half-life of most of the waste to be buried to a couple of hundred years, overcoming the concerns of the public related to the long-life of the waste. This research has been supported since that date by the successive French governments. First it allows France to demonstrate that recycling the long lived fission products is not worth to be done, and in the new Waste Management Act voted in 2006, it was decided to focus the work on the sole minor actinides. This research effort was very significant and was for a significant part conducted within the well-known Atalante nuclear facility in Marcoule. Over the 25 years of development, different types of strategies were studied, from the early multi-stage and complex DIAMEX-SANEX-SESAME processes to the most recent innovative SANEX, covering both the grouped extraction of MA within the GANEX process and the most recent sole-Americium recycling within the EXAm process. These developments were supported by a robust and long-standing approach allowing successively the screening of the potential extractants, the quantification of their extractive properties, the development of relevant chemical models to model the actinides-extracting molecules interactions the development of specific separation equipments. At the end, all these processes were successively qualified on a few kg of spent nuclear fuel within the Atalante CBP facility. This wide research program allows France to get in hands a flexible portfolio of MA recycling processes for different types of strategies that could in the future be industrially deployed after an industrial upscaling phase. In order to complete this large program, CEA initiated in 2010 a demonstration experiment, the so-called integral experiment, which aims to re-irradiate in a Material Testing Reactor some fuel pellet manufactured from recycled Americium. A few grams of americium have already been recovered from commercial spent nuclear fuel thanks to the EXAm process and is now going to be converted in powder and pellets.This large research program also associated the European scientific community thanks to successive European Research Projects which were selected and funded by the European Commission under the coordination of CEA. With this long-standing research program, France demonstrated the feasibility of recycling minor actinides for transmutation within 4th generation fast neutrons reactors. A general overview of these 25 years of successful and innovative research history will be synthesised in this presentation.