Extraction behavior of radiolytic degradation compounds of methylated tetradecyl diglycolamide (mTDDGA)

Whatever the future may bring for nuclear power, spent nuclear fuel (SNF) has been produced and therefore must be dealt with, whether it is direct disposal in a geological repository or reprocessing the SNF beforehand. To date, the only industrial scale reprocessing method is the Plutonium Uranium Reduction Extraction (PUREX) process. However, due to nonproliferation demands, the urge for other reprocessing methods has arisen. This has led to the development of grouped actinide extraction (GANEX) processes, consisting out of two cycles: GANEX-1 to separate bulk uranium from SNF and GANEX-2 to extract the remaining actinides (An) from the lanthanides (Ln) and fission products. One option as second GANEX cycle is the EURO-GANEX process (European collaboration project ACSEPT), which uses TODGA (a diglycolamide) and DMDOHEMA (a malonamide) in kerosene for the An/Ln co-extraction. EURO-GANEX has been successfully demonstrated on fast reactor SNF. However, there is still room for improvement, TODGA and DMDOHEMA could be replaced by mTDDGA on its own. Since radiolytic degradation is inevitable under highly radioactive conditions during reprocessing, formed degradation compounds (DCs) of mTDDGA could affect the solvent extraction. Therefore, the extraction behavior of radiolytic DCs of mTDDGA is characterized in this work with batch solvent extractions, radioanalysis and mass spectrometry. One amide-type DC shows a remarkable selectivity for Pu, while a diglycolamide DC contributes to An/Ln extraction but causes precipitation.