The radiolytic stability of TODGA (N, N, N’, N’-tetraoctyldiglycolamide), which is considered one of the extractans with higher possibilities to be applied for nuclear hydrometallurgical partitioning processes, has been studied in this paper against gamma radiation. Several irradiation experiments have been carried out both, at different experimental conditions and solvent formulations, to know their influence on the ligand stability. After qualitative analysis by HPLC-MS, the identified degradation products were synthesised to verify the assigned structures, to test their extraction properties, and to quantify them in all degraded TODGA samples

The hydrometallurgical separation concepts for the recycling of irradiated nuclear fuels developed in Europe are presented and discussed. Whilst Part 1 of the review focused on concepts for heterogeneous recycling of minor actinides, this article focuses on group recycling of transuranic actinides, which would support homogeneous recycling scenarios. Most of these concepts were developed within European collaborative projects and involve solvent extraction processes separating all the actinides (U-Cm) in two cycles. The first cycle uses a monoamide extractant to recover uranium leaving all the transuranic actinides in the aqueous raffinate with the fission products. The second cycle aims for a group recovery of the transuranium elements and several strategies have been proposed for this stage. In this review article, the various solvent extraction processes are summarised and the key features of the process schemes are compared.

The stability against gamma radiation of MeTODGA (methyl tetraoctyldiglycolamide) and Me₂TODGA (dimethyl tetraoctyldiglycolamide), derivatives from the well-known extractant TODGA (N,N,N′,N′-tetraoctyldiglycolamide), were studied and compared. Solutions of MeTODGA and Me₂TODGA in alkane diluents were subjected to ⁶⁰Co γ-irradiation in the presence and absence of nitric acid and analyzed using LC-MS to determine their rates of radiolytic concentration decrease, as well as to identify radiolysis products. The results of product identification from three different laboratories are compared and found to be in good agreement. The diglycolamide (DGA) concentrations decreased exponentially with increasing absorbed dose. The MeTODGA degradation rate constants (dose constants) were uninfluenced by the presence of nitric acid, but the acid increased the rate of degradation for Me₂TODGA. The degradation products formed by irradiation are also initially produced in greater amounts in acid-contacted solution, but products may also be degraded by continued radiolysis. The identified radiolysis products suggest that the weakest bonds are those in the diglycolamide center of these molecules.