AUTOMACT

The objective of this basic research project is to develop a new strategy for the treatment of radioactive effluents based on the use of a porous functionalized support. This support would allow at the same time the separation of the RadioNucleide (RN) using a selective organic function, and their encapsulation after collapse of the porosity by a "soft" way (sol-gel, heating under stress, irradiation effect). This new concept would result in obtaining a primary wasteform matrix. Mesoporous silicas will be used as model support materials, because the nanometric size of their pores allows easy closure. Furthermore, the silica has a chemical composition close to high-level nuclear waste packaging materials (glass). This new so-called separation / conditioning strategy would constitute a significant simplification of the number of step, compared to "traditional" processes for the treatment of radioactive effluents. Such traditionnal processes usually require a concentration step of radioactivity (evaporation, precipitation, etc.), followed by of a embedding step. It could be adapted to any type of liquid effluents, aqueous or organic, containing radionuclides emitter alpha, beta, gamma. This process could be interesting for the treatment of effluents produced in nuclear installations (STEL ...), but also for the treatment of effluents from dismantling sites because of its compactness. In this project we will focus our study on the treatment of effluents containing actinides, which have a significant radiotoxicity linked to the alpha decays induced . This mode of disintegration could be beneficial for the collapse of the mesoporous structure , leading directly to a "primary wasteform matrix". The closure of the porosity under self-irradiation will therefore be particularly studied, with the realization of materials doped with short-life actinides (244Cm, 238Pu). Another innovative aspect of the AUTOMACT project will be the search and grafting of selective actinide ligands. For that, tributyl phosphate, which is used in the Purex process for the separation of uranium and plutonium, is a potential candidate. The purpose of this project is therefore to propose a new all-in-one RN separation / conditioning route using specific materials allowing both decontamination operations and their simple evolution towards a primary containment matrix.