Implications of 2-hydroxy-N-octylacetamide and N-octylacetamide, two important TODGA degradation compounds, on the actinides partitioning processes

Within the advanced nuclear fuel cycle option, N, N, N’, N’ -tetraoctyldiglycolamide (TODGA) is considered one of the most promising extractants for lanthanides and minor actinides and is involved in most separation strategies currently under development. Despite its resistance to harsh operational conditions, TODGA degrades, resulting in the formation of different degradation compounds (DCs). These DCs can accumulate, affecting original performance and efficiency of the process, since they are not easily removed. Additionally, the generation and accumulation of these DCs can lead to secondary degradation that produces other DCs. Thus, understanding its behavior is necessary to improve process performance and ensure safe operation at an industrial scale. This work studies the physico-chemical properties (solubility, density, and viscosity), extraction properties, and the resistance against gamma radiation of two important TODGA degradation compounds, 2-Hydroxyl- N -Octylacetamide (HNOA) and N -Octylacetamide (NOA), from the point of view of their accumulation. The obtained outcomes give insights into the effects of secondary degradation and its behavior in a TODGA-degraded solvent, including the extraction of some problematic fission products. This will enable a better design of washing strategies to remove problematic DCs which, together with the identification and application of appropriate masking agents, will suppress undesired extraction phenomena. Moreover, this study contributes to a deeper understanding of the chemistry of TODGA-degraded solvent systems, essential for predicting their behavior in separation processes associated with advanced nuclear fuel cycles. • Radiolytic stability and implications on the extraction process were studied • HNOA and NOA accumulation affects considerably the TODGA solvent properties • Undesirable fission products extraction by HNOA and NOA compounds • HNOA and NOA gamma irradiation and their composition analysis performed by HPLC-MS