Development of a selective americium separation process using TPAEN as a water-soluble stripping agent

International audienceRecycling americium from spent fuels is an important option considered for the future nuclear cycle. The PUREX solvent extraction process can be used to separate U and Pu from a dissolution solution of spent fuel in nitric acid. Then in a second step americium should be separated from fission products and especially lanthanides but also from curium. For this purpose, a new liquid-liquid extraction process is under development using TODGA as an extractant in the organic phase and TPAEN as a selective Am stripping agent in the aqueous phase. With this promising system it is possible to co-extract Am, Cm and lanthanides at high acidity and then selectively strip americium from the loaded organic phase at pH around 1 with TPAEN. Batch data were acquired to evaluate best conditions to develop a liquid-liquid extraction flowsheet and the effect of several parameters on Am/Cm was evaluated like concentration of ligand, cations, temperature, etc

Development of a selective americium separation process using TPAEN as a water-soluble stripping agent

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Development of a Selective Americium Separation Process using H4TPAEN as Water-Soluble Stripping Agent

Recycling americium from spent nuclear fuel is considered as an important option for a future sustainable nuclear fuel cycle. The PUREX solvent extraction process allows to separate uranium and plutonium from a solution of spent fuel dissolved in nitric acid. In a second step, it would be desirable to separate americium from fission products, and especially lanthanides, but also from curium in order to further transmute americium in future fast neutron reactors. For this purpose, we report the investigation of a new solvent extraction process based on the use of TODGA as an extractant in the organic phase and H4TPAEN as a selective Am(III) stripping agent in the aqueous phase. With this promising system it is possible to co-extract Am, Cm and lanthanides at high acidity and then selectively strip americium from the loaded organic phase at pH around 1 with H4TPAEN. Batch extraction data were acquired to evaluate best conditions to develop a liquid-liquid extraction flow sheet. The influence of several parameters like concentration of ligand, cations and temperature on Am(III)/Cm(III) and Am/lanthanides separation was evaluated. Especially, the ability of H4TPAEN complexing agent to strip macro-concentrations of Am was demonstrated

Selective separation of Am(III) from PUREX Raffinate with a TODGA-based solvent using innovative hydrophilic complexing agents

Americium is the main contributor to the longtermradiotoxicity and to the heat generation of glassesused for HLW conditioning. To decrease these impactsand to avoid the difficult recycling of curium, the selectiveseparation and recovery of a pure americium productdirectly from PUREX raffinate is envisaged in this study.The new approach is based on the co-extraction oflanthanide(III) and actinide(III) cations from a PUREXraffinate into an organic phase containing N,N,N’,N’-tetraoctyl-diglycolamide (TODGA) as extractant,followed by the subsequent selective stripping of Am(III)and separation from Cm(III) and lanthanides. Threewater-soluble selective ligands were studied: H4TPAENdeveloped at the CEA Marcoule, TS-BTPhen developed atthe University of Reading, and SO3-Ph-BTBP developedat KIT. Very promising results were achieved for allsystems with a quite high Cm(III)/Am(III) selectivitybetween 3-4 to carry out the difficult separation atreasonably high process relevant nitric acid acidities.Numerous batch experimental data were acquired for thedevelopment of the extraction model. Finally, tests onsingle centrifugal contactors were conducted to getinformation on the kinetic and hydraulic performance ofthe system. Finally, tests on single centrifugal contactorswere conducted to get information on the kinetic andhydraulic performance of the system

Teriflunomide and Time to Clinical Multiple Sclerosis in Patients With Radiologically Isolated Syndrome

International audienceImportance Radiologically isolated syndrome (RIS) represents the earliest detectable preclinical phase of multiple sclerosis (MS) punctuated by incidental magnetic resonance imaging (MRI) white matter anomalies within the central nervous system. Objective To determine the time to onset of symptoms consistent with MS. Design, Setting, and Participants From September 2017 to October 2022, this multicenter, double-blind, phase 3, randomized clinical trial investigated the efficacy of teriflunomide in delaying MS in individuals with RIS, with a 3-year follow-up. The setting included referral centers in France, Switzerland, and Turkey. Participants older than 18 years meeting 2009 RIS criteria were randomly assigned (1:1) to oral teriflunomide, 14 mg daily, or placebo up to week 96 or, optionally, to week 144. Interventions Clinical, MRI, and patient-reported outcomes (PROs) were collected at baseline and yearly until week 96, with an optional third year in the allocated arm if no symptoms have occurred. Main outcomes Primary analysis was performed in the intention-to-treat population, and safety was assessed accordingly. Secondary end points included MRI outcomes and PROs. Results Among 124 individuals assessed for eligibility, 35 were excluded for declining to participate, not meeting inclusion criteria, or loss of follow-up. Eighty-nine participants (mean [SD] age, 37.8 [12.1] years; 63 female [70.8%]) were enrolled (placebo, 45 [50.6%]; teriflunomide, 44 [49.4%]). Eighteen participants (placebo, 9 [50.0%]; teriflunomide, 9 [50.0%]) discontinued the study, resulting in a dropout rate of 20% for adverse events (3 [16.7%]), consent withdrawal (4 [22.2%]), loss to follow-up (5 [27.8%]), voluntary withdrawal (4 [22.2%]), pregnancy (1 [5.6%]), and study termination (1 [5.6%]). The time to the first clinical event was significantly extended in the teriflunomide arm compared with placebo, in both the unadjusted (hazard ratio [HR], 0.37; 95% CI, 0.16-0.84; P = .02) and adjusted (HR, 0.28; 95% CI, 0.11-0.71; P = .007) analysis. Secondary imaging end point outcomes including the comparison of the cumulative number of new or newly enlarging T2 lesions (rate ratio [RR], 0.57; 95% CI, 0.27-1.20; P = .14), new gadolinium-enhancing lesions (RR, 0.33; 95% CI, 0.09-1.17; P = .09), and the proportion of participants with new lesions (odds ratio, 0.72; 95% CI, 0.25-2.06; P = .54) were not significant. Conclusion and Relevance Treatment with teriflunomide resulted in an unadjusted risk reduction of 63% and an adjusted risk reduction of 72%, relative to placebo, in preventing a first clinical demyelinating event. These data suggest a benefit to early treatment in the MS disease spectrum. Trial Registration ClinicalTrials.gov Identifier: NCT0312265