The AmSel Process Selective Separation of Americium from PUREX raffinate Christoph Wagner, Udo Müllich, Andreas Geist, Petra J. Panak KIT Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu
Introduction Partitioning and Transmutation: Strategy to reduce long term radiotoxicity and heat load of nuclear waste. Aim: separation of Pu and minor actinides (Np, Am and Cm) and transmuting them into short-lived or stable nuclides. Our goal: selective extraction of Am(III) from PUREX raffinate separation of Am(III) from Cm(III), Ln(III) & other fission products (FP) and corrosion products (CP) 2
Why separate americium from curium? Curium: no significant impact on long-term radiotoxicity or heat load of nuclear waste High neutron dose rates and decay heat complicate production of new nuclear fuel disposal in high active waste Separation of Am(III) should be performed early in the process PUREX Am Cm FP Ln Am(III)/(Cm(III) + Ln(III) + FP) sep n Pu U Np Cm + Ln + FP Am EXAm process already successfully tested Bollesteros, M.-J.; Calor, J.-N.; Costenoble, S.; Montuir, M.; Pacary, V.; Sorel, C.; Burdet, F.; Espinoux, D.; Hérès, X.; Eysseric, C., Procedia Chem. 2012, 7, 178 183. 3
Strategy Co-extraction of Am(III), Cm(III) and Ln(III) Selective Am(III) stripping 4
Strategy Co-extraction of Am(III), Cm(III) and Ln(III) TODGA Extracts An(III) + Ln(III) from HNO 3 Rejects most non-ln fission products Rejects corrosion products Successfully used in DIAMEX and i-sanex processes 5
Strategy TODGA prefers Cm(III) over Am(III) SF Cm(III)/Am(III) = 1.6 Requirement for selective Am(III) stripping: Ligand has to prefer Am(III) over Cm(III) Well soluble in water / nitric acid BTBP prefers Am(III) over Cm(III) SF Am(III)/Cm(III) = 1.6 Water soluble BTBP? SF(TODGA) SF(BTBP) = 2.6? 6
Extraction experiments with TODGA and SO 3 -Ph-BTBP 10 4 10 4 10 3 10 3 10 2 10 1 10 2 D(M(III)) 10 0 10-1 10-2 10-3 Am(III) Am(III) Cm(III) Eu(III) SF Cm(III)/Am(III) 10 1 10 0 10-1 SF 10-4 10-1 10 0 [HNO 3 ] ini [mol/l] SF Cm(III)/Am(III) = 2.5 3 SF Eu(III)/Am(III) 10-2 Aq. phase: 20 mm SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) in HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 7
Extraction experiments with TODGA and SO 3 - Ph-BTBP D(M(III)) 10000 1000 100 10 1 0,1 D(Am(III)) D(Eu(III)) D(La(III)) D(Ce(III)) D(Pr(III)) D(Nd(III)) D(Sm(III)) D(Eu(III)) D(Gd(III)) D(Am(III)) D(Cm(III)) 0,01 1E-3 1E-4 10-1 10 0 [HNO 3 ] ini [mol/l] Aq. phase: 20 mm SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) and 6 mg/l of each Ln(III), Y(III) and La(III) in HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 8
Extraction experiments with TODGA and SO 3 -Ph-BTBP D(Am(III)) 10 3 D(Eu(III)) D(Am(III)) D(Cm(III)) 10 3 D(M(III)) 10 2 10 1 10 0 SF Cm(III)/Am(III) 10 2 10 1 SF Cm(III)/Am(III) 10-1 slope = -1 3 0.2 10 0 10-2 10-1 10 0 10 1 [SO 3 -Ph-BTBP] 10-1 Formation of 1:1 complex? TRLFS studies Aq. phase: SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) in 0.51 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 9
Complexation of Cm(III) with SO 3 -Ph-BTBP Cm(III) emission spectra with increasing SO 3 -Ph-BTBP concentration in 0.5 M HNO 3 597.1 nm 594.6 nm 620.1 nm c(aq-btbp) in mol/l 0 9.80 E-7 2.41 E-6 3.81 E-6 5.16 E-6 6.91 E-6 9.00 E-6 1.10 E-5 1.29 E-5 1.92 E-5 2.55 E-5 3.37 E-5 4.18 E-5 4.97 E-5 6.52 E-5 8.38 E-5 1.69 E-4 3.21 E-4 5.40 E-4 8.84 E-4 1.20 E-3 1.50 E-3 580 590 600 610 620 630 1,0 0,8 [Cm(solv)] 594.6 nm 597.1 nm 620.1 nm [Cm(solv)] Wavelength (nm) [Cm(SO 3 -Ph-BTBP) 2 ] 5-580 590 600 610 620 630 Wavelength (nm) only one complex species 0,6 0,4 0,2 [Cm(SO 3 -Ph-BTBP) 2 ] 5-0,0 10-6 10-5 10-4 10-3 [SO 3 -Ph-BTBP] [mol/l] 10 30.04.2015
Complexation of Eu(III) with SO 3 -Ph-BTBP Eu(III) 7 F 4 band emission spectra with increasing SO 3 -Ph-BTBP concentration in 0.5 M HNO 3 681.9 nm 686.1 nm 694.8 nm 692.3 nm 695.5 nm 698.2 nm 702.0 nm c(aq-btbp) in mol/l 0 4.98 E-6 1.99 E-5 3.97 E-5 6.93 E-5 9.87 E-5 1.47 E-4 1.95 E-4 2.67 E-4 3.37 E-4 4.29 E-4 5.20 E-4 6.08 E-4 6.96 E-4 7.81 E-4 9.47 E-4 1.11 E-3 1.34 E-3 1.63 E-3 670 680 690 700 710 720 Wavelength (nm) 1,0 [Eu(SO 3 -Ph-BTBP) 2 ] 5- [Eu(SO 3 -Ph-BTBP)] - [Eu(solv)] [Eu(solv)] [Eu(SO 3 -Ph-BTBP) 2 ] 5-0,8 670 680 690 700 710 720 Wavelength (nm) 0,6 0,4 2 complex species formed, primarily 1:2 complex 0,2 0,0 [Eu(SO 3 -Ph-BTBP)] - 10-5 10-4 10-3 10-2 [SO 3 -Ph-BTBP] [mol/l] 11 30.04.2015
Complexation of Cm(III) with SO 3 -Ph-BTBP 3+ +SO 3 -Ph-BTBP 4-3 -SO 3 -Ph-BTBP 4- -SO 3 -Ph-BTBP 4- - +SO 3 -Ph-BTBP 4- logk 01 logk 12 3 2 5- log([cm(so 3 -Ph-BTBP) 2 ]/[Cm 3+ (solv)]) 0-1 -2-3 -4-5 Cm(III) complexation -6,0-5,6-5,2-4,8-4,4-4,0-3,6 log([so 3 -Ph-BTBP] free ) Slope 2.0 0.1 log 02 log([eu(so 3 -Ph-BTBP) n ]/[Eu(SO 3 -Ph-BTBP) n-1 ]) 0-1 -2-3 Eu(III) complexation n = 2 slope 0.9 0.2 n = 1 slope = 1.2 0.2-4,8-4,4-4,0-3,6-3,2 log([so 3 -Ph-BTBP] free ) log 02 = 7.3 ± 0.3 log 02 = 5.4 ± 0.5 log 02 = 1.9 12 30.04.2015
TRLFS with extraction experiments 2 phase extraction experiments containing Cm(III)/Eu(III) in the aq. Phase aq. phase extraction experiment [Cm(SO 3 -Ph-BTBP) 2 ]5- TRLFS spectrum aq. phase extraction experiement [Eu(SO 3 -Ph-BTBP) 2 ] 5- TRLFS spectrum 590 600 610 620 630 Wavelength (nm) 670 680 690 700 710 720 Wavelength (nm) SO 3 -Ph-BTBP forms 1:2 complexes in extraction experiments Aq. phase: 20 mm SO 3 -Ph-BTBP, Cm(III)-248 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 13
Complexation of Cm(III) at ph 3 TRLFS investigation of Cm(III) with SO 3 -Ph-BTP showed the formation of intermediate complexes studies with SO 3 -Ph-BTP were performed in water at ph 3 investigation of Cm(III) complexation with SO 3 -Ph-BTBP at ph 3 C. M. Ruff, U. Müllich, A. Geist and P. J. Panak, Dalton Trans., 2012, 41, 14594-14602. 14
Complexation of Cm(III) at ph 3 Cm(III) emission spectra with increasing SO 3 -Ph-BTBP concentration in 10-3 M HClO 4 590 600 610 620 630 Wavelength (nm) c(so 3 -Ph-BTBP) in mol/l 0 1.96 E-7 3.85 E-7 5.66 E-7 7.41 E-7 9.91 E-7 1.23 E-6 1.45 E-6 1.67 E-6 2.48 E-6 3.67 E-6 4.84 E-6 5.98 E-6 7.09 E-6 8.17 E-6 9.23 E-6 1.03 E-5 1.77 E-5 2.87 E-5 log 02 = 10.4 ± 0.4 (log (0.5 M HNO 3 ) = 7.3 ± 0.3) log([cm(aq-btbp) n ]/[Cm(aq-BTBP) n-1 ]) 1,0 0,8 0,6 0,4 0,2 0,0 0,0-0,2-0,4-0,6-0,8-1,0-1,2-1,4 calcd solvensspecies calcd [Cm(SO 3 -Ph-BTBP)] - calcd [Cm(SO 3 -Ph-BTBP) 2 ] 5- Solvensspezies [Cm(SO 3 -Ph-BTBP)] - [Cm(SO 3 -Ph-BTBP) 2 ] 5-10 -8 10-7 10-6 10-5 10-4 [SO 3 -Ph-BTBP] [mol/l] n = 1 slope 1.0 0.2 n = 2 slope 1.1 0.2-1,6-6,6-6,4-6,2-6,0-5,8-5,6-5,4 log[aq-btbp] free 15 large influence of solvent
Complexation of Cm(III) in different media c(so 3 -Ph-BTBP) in mol/l 0.5 M NaClO 4, ph 3 0.5 M NaNO 0 3, ph 3 1.98 E-7 5.93 E-7 1.08 E-6 1.47 E-6 1.95 E-6 2.33 E-6 2.61 E-6 2.90 E-6 3.27 E-6 3.73 E-6 4.37 E-6 5.27 E-6 7.02 E-6 1.61 E-5 2.94 E-5 4.66 E-5 c(so 3 -Ph-BTBP) in mol/l 0 1.99 E-7 5.96 E-7 1.09 E-6 1.67 E-6 2.25 E-6 2.91 E-6 3.84 E-6 4.30 E-6 4.94 E-6 5.65 E-6 6.54 E-6 7.83 E-6 9.49 E-6 1.84 E-5 590 600 610 620 630 Wavelength (nm) 0.5 M HClO 4 590 600 610 620 630 c(so 3 -Ph-BTBP) in mol/l 0 9.84 E-7 2.42 E-6 3.82 E-6 5.18 E-6 6.93 E-6 9.04 E-6 1.10 E-5 1.30 E-5 1.93 E-5 2.56 E-5 3.38 E-5 4.99 E-5 6.54 E-5 8.42 E-5 1.63 E-4 3.17 E-4 5.39 E-4 8.87 E-4 Wavelength (nm) 16 590 600 610 620 630 Wavelength (nm)
Influence of medium on conditional stability constant M(III) Solvens log 01 logk 12 log 02 Cm 10-3 M HClO 4 5.3 ± 0.3 5.1 ± 0.3 10.4 ± 0.4 Cm 0.5 M HNO 3 - - 7.3 ± 0.3 Cm 0.5 M NaClO 4 - - 9.7 ± 0.3 Cm 0.5 M NaNO 3 - - 9.4 ± 0.3 Cm 0.5 M HClO 4 - - 8.5 ± 0.4 Large effect of medium on speciation and conditional stability constant 17
Influence of ionic strength ionic strength in mol/l 1.0 E-3 1.0 E-2 1.8 E-2 4.3 E-2 8.5 E-2 1.7 E-1 4.2 E-1 7.9 E-1 1.3 2.3 Cm-SO 3 -Ph-BTBP complexation with increasing ionic strength log 01 12 11 logk 12 log 02 590 600 610 620 630 Wavelength (nm) ionic strength in mol/l 1.0 E-3 1.0 E-2 1.8 E-2 4.3 E-2 8.5 E-2 1.7 E-1 4.2 E-1 7.9 E-1 1.3 2.3 cond. stability constant 10 9 8 7 6 5 4 3 2 1 0 1E-3 0,01 0,1 1 ionic strentgh (mol/l) 580 590 600 610 620 630 Wavelength (nm) 18
Conclusion The SO 3 -Ph-BTBP/TODGA system shows good performance for the separation of Am(III)/Cm(III). The system does not require buffers, auxiliary ligands or salting out agents. SO 3 -Ph-BTBP forms 1:2 complexes during extraction. Formation of the same complexes in monophasic and biphasic experiments. The applied medium has a large effect on the speciation and the conditional stability constants of M(III)-SO 3 -Ph-BTBP complexes. 19
Outlook Extraction experiments at elevated temperatures. Investigation of SO 3 -Ph-BTBP loading with realistic Am(III) concentrations. Spectroscopic investigation of Am(III)-SO 3 -Ph-BTBP complexes. 20
Thank you for your attention Acknowledgements to: Prof. Dr. Geckeis The partitioning group Tanja Kisely and Cornelia Walschburger And all colleagues from INE Acknowledgements to the Commission of European Community for financial support 21
Complexation of Cm(III) in the org. phase TRLFS experiments with organic phase of extraction experiment org. phase extraction experiment [Cm(TODGA) 3 ](NO 3 ) 3 org. phase extraction experiment [Eu(TODGA) 3 ](NO 3 ) 3 TRLFS spectrum 580 590 600 610 620 630 Wavelength (nm) 580 590 600 610 620 630 Wavelength (nm) No evidence for the formation of mixed complexes sensitivity too low? Aq. phase: 20 mm SO 3 -Ph-BTP, Cm(III)-248 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 22
Fluorimetric measurements with org. Phase 3,20 2,56 1,92 Idea: Utilizing the energy transfer from ligand to metal to selectively excite the Eu(III) in mixed complexes 580 590 600 610 620 630 Emissionwavelength (nm) 280 260 320 300 360 340 380 400 1,28 0,64 440 420 Excitationwavelength (nm) 23 Aq. phase: 20 mm SO 3 -Ph-BTP, 30 mm Eu(NO 3 ) 3 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80
Schematic flowsheet TODGA Extraction/ scrubbing Am(III) + Cm(III) + Ln(III) FP + CP TODGA Am(III) stripping Cm + Ln(III) Cm(III) + Ln(III) stripping HAR FP + CP Feed Am(III) + Cm(III) + Ln(III) + FP + CP Scrub sol n Product Am(III) Am(III) SO 3 -Ph-BTBP HAR Cm(III) + Ln(III) Cm(III) + Ln(III) Cm(III) + Ln(III) strip sol n 24
pk a value of SO 3 -Ph-BTBP 1,0 extinction 100000 80000 60000 40000 20000 ph 226 nm 305 nm 327 nm 319 nm 0 200 250 300 350 400 450 wavelength [nm] pk a = 2.2 ± 0.2 7 3 2,7 2,4 2,1 1,75 1.53 1,28 1,01 0,68 0,36-0,06-0,36 log( (erste protonierte Spezies)/ (unprotonierte Spezies)) 0,8 0,6 0,4 0,2 0,0 10-7 10-6 10-5 10-4 10-3 10-2 10-1 10 0 10 1 0,6 0,4 0,2 0,0-0,2-0,4-0,6-0,8 calcd unprotonated ligand calcd protonated ligand unprotonated ligand protonated ligand a(h + ) slope = 1.00-1,0-3,2-3,0-2,8-2,6-2,4-2,2-2,0-1,8-1,6-1,4 log(a(h+)) 25
TRLFS Setup 26 Christoph Wagner A new system for the separation of americium from PUREX raffinate
Spectroscopic properties of Cm(III) weak ligand field strong ligand field - Identification und quantification of different species - Large effect of changes in first coordination sphere - Little effect of changes in second coordination sphere 27 Christoph Wagner A new system for the separation of americium from PUREX raffinate
Spectroscopic properties of Eu(III) wavelength (nm) Small shifts of the emission bands with changes in inner coordination sphere Characteristic splitting Information on the coordination structure and symmetry 28 Christoph Wagner A new system for the separation of americium from PUREX raffinate