| 1. |
- Lyseid Authen, Thea, 1993, et al.
(författare)
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An overview of solvent extraction processes developed in Europe for advanced nuclear fuel recycling, Part 2 — homogeneous recycling
- 2022
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Ingår i: Separation Science and Technology. - : Informa UK Limited. - 1520-5754 .- 0149-6395. ; 57:11, s. 1724-1744
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Forskningsöversikt (refereegranskat)abstract
- The hydrometallurgical separation concepts for the recycling of irradiated nuclear fuels developed in Europe are presented and discussed. Whilst Part 1 of the review focused on concepts for heterogeneous recycling of minor actinides, this article focuses on group recycling of transuranic actinides, which would support homogeneous recycling scenarios. Most of these concepts were developed within European collaborative projects and involve solvent extraction processes separating all the actinides (U-Cm) in two cycles. The first cycle uses a monoamide extractant to recover uranium leaving all the transuranic actinides in the aqueous raffinate with the fission products. The second cycle aims for a group recovery of the transuranium elements and several strategies have been proposed for this stage. In this review article, the various solvent extraction processes are summarised and the key features of the process schemes are compared.
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| 2. |
- Aneheim, Emma, 1982, et al.
(författare)
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Single Centrifugal Contactor Test of a Proposed Group Actinide Extraction Process for Partitioning and Transmutation Purposes
- 2015
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Ingår i: Separation Science and Technology. - : Informa UK Limited. - 1520-5754 .- 0149-6395. ; 50:10, s. 1554-1559
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Tidskriftsartikel (refereegranskat)abstract
- In this work a solvent comprising of tri-butyl phosphate and bis-triazinyl, bi-pyridine in cyclohexanone has been used in a single centrifugal contactor test to evaluate its GANEX process potential. It was found that the density of the aqueous phase had to be increased to facilitate phase separation in the centrifuge. The kinetics of the system was also found to be relatively slow in the equipment of choice, especially regarding the stripping. However, it was still possible to recover more than 87% of all actinides in one extraction step with minor fission product contaminations using a flowrate of 30 mL/h.
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| 3. |
- Lyseid Authen, Thea, 1993, et al.
(författare)
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A comparison on the use of DEHBA or TBP as extracting agent for tetra- and hexavalent actinides in the CHALMEX Process
- 2022
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 331:12, s. 5137-5145
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Tidskriftsartikel (refereegranskat)abstract
- The Chalmers Grouped ActiNide EXtraction process is a solvent extraction process for the homogeneous recycling of spent nuclear fuel. The use of TBP for the extraction of tetra- and hexavalent actinides can be problematic for several reasons, including troublesome degradation products causing crud formation, decreased extraction yield and the possibility of explosive red oil reactions. Here, the substitution of TBP by a N,N-dialkyl monoamide, DEHBA, is investigated. The findings suggest that DEHBA can be a suitable extracting agent for use in the CHALMEX solvent, although identified drawbacks need to be further investigated.
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| 4. |
- Lyseid Authen, Thea, 1993, et al.
(författare)
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Batch flowsheet test for a GANEX-type process: the CHALMEX FS-13 process
- 2022
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Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 40:3, s. 189-202
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Tidskriftsartikel (refereegranskat)abstract
- The Chalmers grouped actinide extraction (CHALMEX) process is focused on the co-separation of actinides from all other elements in spent nuclear fuel solution, with the ultimate purpose of transmuting the actinides into shorter-lived and less radiotoxic elements. Based on solvent extraction equilibrium distribution data of actinides and fission products, a preliminary flowsheet was developed and tested in batch mode. The flowsheet consists of one extraction step with the CHALMEX FS-13 solvent (25 mM CyMe4-BTBP in 30% v/v TBP and 70% v/v FS-13), using hydrophilic masking agents (20 mM bimet and 0.2 M mannitol) in the aqueous phase for the complexation of troublesome fission products. Two nitric acid scrub steps (0.5 M HNO3) were efficient in removing co-extracted acid, all molybdenum and the majority of silver. Two stripping stages (0.5 M glycolic acid at pH 4) were efficient in recovery of the actinides from the organic phase. The need for a solvent clean-up stage for the removal of nickel, cadmium, iron and the remaining silver from the organic phase was demonstrated. Based on the distribution data, it was calculated that a 99.9% recovery of americium is possible using only 3 ideal extraction stages, 3 ideal scrubbing stages and 2 ideal stripping stages.
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| 5. |
- Lyseid Authen, Thea, 1993, et al.
(författare)
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Batch Tests for Optimisation of Solvent Composition and Process Flexibility of the CHALMEX FS-13 Process
- 2021
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Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 39:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Studies have been performed with the purpose of determining the optimal solvent composition of a Chalmers grouped actinide extraction (CHALMEX) solvent for the selective co-extraction of transuranic elements in a novel Grouped ActiNide EXtraction (GANEX) process. The solvent is composed of 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo-[1,2,4]-triazin-3-yl)-[2,2’]-bipyridine (CyMe4-BTBP) and tri-n-butyl phosphate (TBP) in phenyl trifluoromethyl sulfone (FS-13). The performance of the system has been shown to significantly depend on the ratios of the two extracting agents and the diluent to one another. Furthermore, the performance of the determined optimal solvent (10 mM CyMe4-BTBP in 30% v/v TBP and 70% v/v FS-13) on various simulated PUREX raffinate solutions was tested. It was found that the solvent extracts all transuranic elements with high efficiency and good selectivity with regard to most other elements (fission products/activation products) present in the simulated PUREX raffinate solutions. Moreover, the solvent was found to extract a significant amount of acid. Palladium, silver, and cadmium were co-extracted along with the TRU-radionuclides, which has also been observed in other similar CHALMEX systems. The extraction of plutonium and uranium was preserved for all tested simulated PUREX raffinate solutions compared to experiments using trace amounts.
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| 6. |
- Schmidt, H., et al.
(författare)
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Gamma and pulsed electron radiolysis studies of CyMe 4 BTBP and CyMe 4 BTPhen: Identification of radiolysis products and effects on the hydrometallurgical separation of trivalent actinides and lanthanides
- 2021
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Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 1879-0895 .- 0969-806X. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- The radiolytic stability of the highly selective ligands CyMe4BTBP and CyMe4BTPhen against ionizing gamma radiation was studied in 1-octanol solution. CyMe4BTBP and CyMe4BTPhen are important extractants for a potential treatment of used nuclear fuel. They were studied under identical experimental conditions to directly compare the effects of gamma and pulsed electron radiolysis on the ligands and systematically study the influence of structural changes in the ligand backbone. Distribution ratios of Am3+, Cm3+ and Eu3+, the residual concentration of CyMe4BTBP and CyMe4BTPhen in solution, and the formation of radiolysis products were studied as a function of absorbed gamma dose and presence of an acidic aqueous phase during irradiation. Quantitative and semi-quantitative analyses were used to elucidate the radiolysis mechanism for both ligands. Addition products of alpha-hydroxyoctyl radicals formed through radiolysis of the 1-octanol diluent to the ligand molecules were identified as the predominant radiolysis products. These addition products also extract trivalent metal ions, as distribution ratios remained high although the parent molecule concentrations decreased. Therefore, the utilization time of a solvent using these extractants under the harsh conditions of used nuclear fuel treatment could be considerably longer than expected. Understanding the radiolysis mechanism is crucial for designing more radiation resistant extractants.
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| 7. |
- Schmidt, H., et al.
(författare)
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Gamma radiolysis of the highly selective ligands CyMe4BTBP and CyMe(4)BTPhen: Qualitative and quantitative investigation of radiolysis products
- 2016
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Ingår i: Atalante 2016 International Conference on Nuclear Chemistry for Sustainable Fuel Cycles. - : Elsevier BV. - 1876-6196. ; 21, s. 32-37
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Konferensbidrag (refereegranskat)abstract
- The highly selective nitrogen donor ligands CyMe4BTBP and CyMe(4)BTPhen where gamma-irradiated under identical experimental conditions in 1-octanol with and without contact to nitric acid solution. Subsequently, solvent extraction experiments were carried out to evaluate the stability of the extractants against gamma-radiation monitoring Am(III) and Eu(III) distribution ratios. Generally, decreasing distribution ratios with increasing absorbed dose were detected for both molecules. Furthermore, qualitative mass spectrometric analyses were performed and ligand concentrations were determined by HPLC-DAD after irradiation to investigate the radiolysis mechanism. An exponential decrease with increasing absorbed dose was observed for both ligands with a faster rate for CyMe(4)BTPhen. Main radiolysis products indicated the addition of one or more diluent molecules (1-octanol) to the ligand via prior production of a-hydroxyoctyl radicals from diluent radiolysis. The addition of nitric acid during the irradiation lead to a remarkable stabilization of the system, as the extraction of Am(III) and Eu(III) did not change significantly over the whole examined dose range. Quantification of the remaining ligand concentration on the other hand showed decreasing concentrations with increasing absorbed dose. The stabilization of D values is therefore explained by the formation of 1-octanol addition products which are also able to extract the studied metal ions.
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| 8. |
- Schmidt, H., et al.
(författare)
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Gamma radiolytic stability of CyMe4BTBP and the effect of nitric acid
- 2015
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Ingår i: Nukleonika. - : Walter de Gruyter GmbH. - 1508-5791 .- 0029-5922. ; 60:4, s. 879-884
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Tidskriftsartikel (refereegranskat)abstract
- The highly selective nitrogen donor ligand CyMe4BTBP for An(III) separation by solvent extraction was irradiated in a 60Co γ-source under varying conditions. Organic solutions of 10 mmol/L ligand in 1-octanol were contacted with different concentrations of nitric acid to observe the influence of an aqueous phase during irradiation. In subsequent liquid-liquid extraction experiments, distribution ratios of 241Am and 152Eu were determined. Distribution ratios decreased with increasing absorbed dose when irradiation was performed in the absence of nitric acid. With addition of nitric acid, initial distribution ratios remained constant over the whole examined dose range up to 300 kGy. For qualitative determination of radiolysis products, HPLC-MS measurements were performed. The protective effect of nitric acid was confirmed, since in samples irradiated with acid contact, no degradation products were observed, but only addition products of the 1-octanol molecule to the CyMe4BTBP molecule.
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| 9. |
- Wilden, A., et al.
(författare)
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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
- 2016
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Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 34:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The stability of solvents containing the C5-BPP (2,6-Bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) extractant against gamma-irradiation up to 330 kGy adsorbed dose was evaluated using HPLC mass spectrometric and solvent extraction methods. The main radiolysis products were identified using high-resolution mass spectrometry. Quantitative analysis of the residual C5-BPP concentration in irradiated samples was accomplished by a specifically developed MRM (Multiple Reaction Monitoring) method. A mixture of C5-BPP with 2-bromohexanoic acid in kerosene and 1-octanol, which had been used in an actinide(III)/lanthanide(III) separation process demonstration test, was also studied for its radiolytic stability and a remarkable protective effect of the presence of nitric acid during irradiation was found.
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