Development of experimental irradiation strategies to evaluate the robustness of TODGA and water-soluble BTP extraction systems for advanced nuclear fuel recycling

Abstract

More sustainable nuclear fuel cycle options will entail the implementation of efficient separation processes of actinides from lanthanides, which currently continues being a critical milestone. One of the limiting points to ensure a safe and stable long-term operation is the resistance against radiation of the extraction systems under development. During the latest years, processes like i-SANEX and EURO-GANEX have been developed and tested to separate actinides from lanthanides, addressing the heterogeneous and the homogeneous recycling strategy respectively. Both of them are the result of the combination of an organic phase containing TODGA, and an aqueous phase containing the sulfonated 2,6-bis(5,6-di(sulphophenyl)-1,2,4-triazin-3-yl)pyridine. In this work, we report an extended stability study of the water-soluble SO3-Ph-BTP as part of the full system considering both phases, the organic and aqueous phase. A systematic set of gamma irradiation experiments were carried out in order to explore the effects of each phase and the influence of the experimental irradiation methodology chosen in the global system resistance. For that, different phase composition, oxygen content and contact between phases have been considered to achieve a better simulation of the most relevant process conditions. The current results corroborate not only that the stability of SO3-Ph-BTP has been sub-estimated, but also that the experimental irradiations test for process demonstration should involve the contact between both phases, the corresponding organic and aqueous phase.