Effects of Gamma Irradiation on the Extraction Properties of Innovative Stripping Solvents for i-SANEX/GANEX Processes

Abstract

Recovery of trivalent minor actinides or of all transuranium elements from highly active raffinate could be industrially achieved by innovative Selective ActiNide EXtraction (i-SANEX) and Grouped ActiNide EXtraction (GANEX) processes respectively. All chemicals involved in the partitioning of actinides must be resistant to acidic and radioactive environment, since hydrolysis and radiolysis can have huge impact on process safety and performance. In this work, the hydrolytic and radiolytic stability of two innovative hydrophilic complexing agents, 2 2,6-bis[1-propan-1-ol)-triazolyl)]pyridine (PTD) and 2,6-bis[1-(propan-1,2-dioltriazolyl)]pyridine (PTT), have been investigated as they proved to be endowed with high actinides selectivity. In order to simulate the damage experienced at process conditions, the stripping solutions were aged in HNO3 for several weeks and γ-irradiated up to 200 kGy with 60 Co sources.Batch liquid-liquid extraction tests were performed on fresh, aged and irradiated stripping solutions in order to verify whether ageing and γ-irradiation affect system performance.Furthermore, Nuclear Magnetic Resonance (NMR) analyses were carried out to ascertain the radiation-induced ligand degradation and consequent by-products formation. The stripping solutions manifested so exceptional performance and radiochemical stability, even at harsh process conditions, to demonstrate their industrial applicability to i-SANEX and GANEX processes.

Promising Lipophilic PyTri Extractant for Selective Trivalent Actinide Separation from High Active Raffinate

“…In fact, alterations of both D-values of 241 Am, 244 Cm, and 152 Eu and of the corresponding SFs are within the experimental uncertainty. A comparable radiochemical stability has been highlighted also for the hydrophilic PyTri compound, PyTri-diol …”

“…A comparable radiochemical stability has been highlighted also for the hydrophilic PyTri compound, PyTri-diol. 25 With the aim of further confirming the promising radiochemical stability highlighted and attempting the identification of potential degradation byproducts, HPLC-MS and direct ESI-MS analyses were performed on the same fresh, aged, and irradiated PTEH solutions used in the solvent extraction experiments.…”

Insights into the Complexation Mechanism of a Promising Lipophilic PyTri Ligand for Actinide Partitioning from Spent Nuclear Fuel

“…Besides the widely investigated BTP, BTBP, and BTPhen ligands (Figure , bottom), recently, the pyridine-bistriazole (PyTri) chelating unit (Figure , top left) was found to be similarly promising for the selective An­(III) separation under SANEX conditions. − In particular, the lipophilic 2,6-bis­(1-(2-ethylhexyl)-1H-1,2,3-triazol-4-yl)­pyridine (PyTri-Ethyl-HexylPTEH) ligand proved to be an excellent candidate for the SANEX-like processes (Figure , top right), endowed with a good solubility in the mixtures of organic diluents used, a satisfactory extraction efficiency, a remarkable An selectivity, a fast extraction kinetics and a good radiochemical stability. , …”

The fate of reverse micellar aggregation in irradiated diglycolamide inn-dodecane solution

“…While the aqueous soluble degradation products are not of much concern as they are regarded as innocuous from the process point of view, the organic soluble degradation products usually change the physicochemical properties of the organic phase, including the polarity and aggregation behaviour of molecules in the organic phase to a significant extent. [32][33][34] The changes in the physicochemical properties and aggregation behaviour of the radiolytically degraded organic phase are likely to pose a number of problems in the industrial scale solvent extraction procedure. 34,35 In contrast, most of the studies reported in the literature focus only on the extraction and stripping behaviour of actinides and lanthanides, variation in the physical properties of the radiolytically degraded organic phase and characterisation of degraded products.…”