Gamma-Radiolytic Stability of Solvents Containing C5-BPP (2,6-Bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) for Actinide(III)/Lanthanide(III) Separation

Testing a simple approach for theoretical evaluation of radiolysis products in extraction systems. A case of N,O-donor ligands for Am/Eu separation

“…The samples contacted with nitric acid solutions fully kept their extraction properties aer irradiation up to 500 kGy, while for the samples contacted with pure water or even without contact with aqueous phase the D values for americium dropped down to a value less than 1 at the dose of 300 kGy. A similar protective effect of nitric acid under external gamma-irradiation had been previously observed for some other extractants, such as 2,6-bis-[5-(2,2-dimethyl-propyl)-1H-pyrazol-3-yl]-pyridine in 1-octanol 34 and carbamoylphosphine oxide 35 but it has still not been explained from the view point of preferential radical reaction routes.…”

“…One can see hydrogen substitution at a similar atom in (2,6-bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) radiolysis. 34 Same as for ligand (1), the weakest bonds in the ligand (2) are C arom -C aliph and C-N (Table 8). Also, we didn't observe any bond breaking under gamma-irradiation.…”

Selective extraction of trivalent actinides using CyMe4BTPhen in the ionic liquid Aliquat-336 nitrate

“…The main radiolysis products identied are addition products of the N-heterocyclic ligands and the a-hydroxyoctyl radicals formed by diluent radiolysis. This type of adduct formation mechanism was previously discovered in irradiated solutions of (2,6- 26 Improvement of the radiation stability of the solvent could be achieved by the complete or at least partial replacement of 1-octanol by another diluent that is more resistant to radiation-induced degradation. Such diluent mixtures of 1-octanol/toluene or 1-octanol/hydrogenated tetrapropylene (TPH) were tested by Lewis et al 17 Ionic liquids (ILs) are a relatively new class of compounds that can provide several advantages over molecular diluents in solvent extraction processes at the back-end of the nuclear fuel cycle.…”

“…This type of adduct formation mechanism was previously discovered in irradiated solutions of (2,6-bis(5-(2,2-dimethylpropyl)-1 H -pyrazol-3-yl)pyridine) (C5-BPP) in 1-octanol. 26 Improvement of the radiation stability of the solvent could be achieved by the complete or at least partial replacement of 1-octanol by another diluent that is more resistant to radiation-induced degradation. Such diluent mixtures of 1-octanol/toluene or 1-octanol/hydrogenated tetrapropylene (TPH) were tested by Lewis et al 17 …”

Hexavalent Americium Recovery Using Copper(III) Periodate

“…Several options have been considered to accomplish trivalent actinides/lanthanide separations that would be compatible with advanced nuclear fuel cycle goals. Many of these approaches utilize soft donor (nitrogen, sulfur) complexants or extractants to selectively interact with the actinides over the lanthanides. − These systems can produce separation factors as high as 10 000 between americium and europium but require the use of synthetically complex extractants, can be kinetically slow, or can be prohibitively sensitive to the harsh radiation environment presented from the irradiated nuclear fuel. − Additionally, these methods would require the development of at least two separation steps, since the soft donor chemistry has not been optimized for the group recovery of uranium, neptunium, plutonium, and americium from the fission products. A more direct approach is to remove Am along with U, Np, and Pu after oxidation of the transuranics to the hexavalent state. − This would decrease the amount of secondary waste volumes and would function more similarly to the internationally familiar plutonium uranium redox extraction (PUREX) process.…”