Performance of an i-SANEX System Based on a Water-Soluble BTP under Continuous Irradiation in a γ-Radiolysis Test Loop

Abstract

The i-SANEX solvent formulation consisting of n ominally 0.2 M TODGA/5% 1octanol/dodecane was g-irradiated under realistic conditions in the INL radiolysis test loop, in contact with both extraction and stripping aqueous phases. The extraction aqueous phase was 4.5 2 M HNO 3 , and the stripping aqueous phase was 0.018 M SO 3-Ph-BTP/0.35 M HNO 3. When irradiated in contact with only the 4.5 M HNO 3 phase, the TODGA solvent maintained excellent extraction performance for americium, cerium, europium and neodymium to a maximum absorbed dose of nearly 0.9 MGy. The results for preliminary static, batch irradiations were consistent with test loop findings. When the aqueous phase was changed to that containing the aqueous soluble BTP, the irradiated aqueous phase showed a dramatic color change, but this does not appear to have had adverse effect on solvent extraction performance. The distribution ratios for both the lanthanides and actinides were invariant with a bsorbed dose, and the separation factors were essentially unchanged to a maximum absorbed dose of 174 kGy. The results of ICP-MS analysis of the aqueous and organic phases showed that ruthenium and strontium were not extracted in the presence of the irradiated BTP-aqueous phase. Molybdenum was extracted under both conditions. Further, the build-up of corrosion products of stainless steel in the presence of the BTP was not dramatically greater than in the nitric acid-only system. Phase separation times were not adversely affected by irradiation for either system. The results presented here indicate that the performance of the TODGA/SO 3-Ph-BTP, i-SANEX process under test loop radiolysis is much better than expected based on a literature report using singlephase batch irradiation experiments, and better than might be predicted base on DGA radiolysis studies alone.

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

“…One of the most relevant ligands, 2,6-bis (5,6-di(sulfophenyl)-1,2,4-triazin-3-yl)pyridine (SO3-Ph-BTP), showed a scarce stability in the homogeneous phase, and an opposite behaviour as a biphasic SO3-Ph-BTP/TODGA system 39,40 . arranged with two triazoles guarantees the selectivity for An, as already outlined in recent publications [41][42][43] .…”

Stability studies of GANEX system under different irradiation conditions

“…In addition to these studies, Peterman et al [12] performed quantitative studies of TODGA samples irradiated in contact with HNO 3 but also in contact with SO 3 -Ph-BTP aqueous phase, in static and in dynamic conditions. They concluded that the stability of TODGA and SO 3 -Ph-BTP, and the general performance of the system depends strongly on the simulation of irradiation process conditions.…”

Radiolytic degradation of hydrophilic PyTri ligands for minor actinide recycling

“…Contrariwise to the lipophilic counterpart, poor literature information exists concerning the radiolytic behavior of hydrophilic complexing agents to be used for the MA selective stripping. So far, discordant results have been obtained on the radiation resistance of the non-CHON compliant Bis(di-sulfo-Phenyl)-Triazine-Pyridine (SO3-Ph-BTP), former i-SANEX reference hydrophilic ligand for MA back-extraction [38][39].…”