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Partitioning of Cesium and Strontium from Dissolved Spent LWR fuel using a Novel Crown Ether/Calixarene Solvent

Partitioning of Cesium and Strontium from Dissolved Spent LWR fuel using a Novel Crown Ether/Calixarene Solvent . J. D. Law, C.L. Riddle, J.D. Baker, D. H. Meikrantz, C.A. McGrath, B.J. Mincher, D.R. Peterman, T.A.Todd. Introduction.

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Partitioning of Cesium and Strontium from Dissolved Spent LWR fuel using a Novel Crown Ether/Calixarene Solvent

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  1. Partitioning of Cesium and Strontium from Dissolved Spent LWR fuel using a Novel Crown Ether/Calixarene Solvent J. D. Law, C.L. Riddle, J.D. Baker, D. H. Meikrantz, C.A. McGrath, B.J. Mincher, D.R. Peterman, T.A.Todd

  2. Introduction • Crown ethers have previously been demonstrated for the removal of strontium from acidic waste solutions and calixarenes have been demonstrated for the removal of cesium • A novel solvent, consisting of a crown ether/calixarene mixture is being developed for the simultaneous separation of Cs and Sr from acidic media • This solvent consists of DtBuCH18C6 (extractant in SREX process) for the extraction of Sr, BOBCalixC6 (extractant in CSSX process) for the extraction of Cs, and a Cs-7SB modifier in an Isopar L diluent.

  3. Strontium Extraction,SREX Process,and Caustic Side Solvent Extraction, CSSX Process SREX Solvent 0.15 M DtBuCH18C6 1.2 M TBP Isopar L CSSX Solvent 0.007 M BOBCalixC6 0.750 M Cs-7SB modifier 0.003 M TOA Isopar L SREX mixture components combined and stirred for one hour CSSX solvent received already prepared Aqueous samples consisted of: 137Cs tracer, with carrier (0.0001 M CsNO3) in HNO3 85Sr tracer, with carrier (0.001 M Sr(NO3)2 in HNO3

  4. Molecular Structures of the Cesium and Strontium Extractants and the Cs-7SB Modifier BOBCalixC6 DtBuCH18C6 Calix[4]arene-bis-(tert-octylbenzo- 4,4′,(5′)-Di-(t-butyldicyclo-hexano)- crown-6) 18-crown-6 Cs-7SB modifier 1-(2,2,3,3-tetrafluoropropoxy)-3- (4-sec-butylphenoxy)-2-propanol

  5. Extraction of Sr with SREX (Strontium Extraction) Organic phase: 0.15M DtBuCH18C6, 1.2M TBP in Isopar L at ambient temp. (23oC ± 3o)Aqueous phase: HNO3= varied concentrations, 85Sr tracer Dist. at 1MHNO3: Sr = 0.7 (Consistent with previous work, Dietz et al., 1995)

  6. Extraction of Cs with CSSX (Caustic Side Solvent Extraction)Organic phase: 0.007M BOBCalixC6, 0.75M Cs-7SB modifier, 0.003M TOA in Isopar L at ambient temp.Aqueous phase: HNO3= varied concentrations, 137Cs tracer Dist. at 1M HNO3: Cs = 7.9

  7. Extraction of Cs and Sr with the New Mixed Solvent at Ambient Temp. Organic phase: 0.15M DtBuCH18C6, 0.007M BOBCalixC6, 0.75M Cs-7SB modifier in Isopar LAqueous phase: HNO3= varied conc., 137Cs and 85Sr tracers

  8. Extraction of Cs and Sr from CSSX and Varied DtBuCH18C6 Concentrations at Ambient Temp. Organic phase: 0.007M BOBCalixC6, 0.75M Cs-7SB modifier, 0.003M TOA, DtBuCH18C6 conc. from 0.045 to 0.180M in Isopar LAqueous phase: HNO3= 1M, 137Cs and 85Sr tracers

  9. Extraction of Cs and Sr with DtBuCH18C6, BOBCalixC6 and Varied Cs-7SB Modifier Conc.Organic phase: 0.15M DtBuCH18C6, 0.007M BOBCalixC6, Cs-7SB mod. conc. from 0.01 to 1.0M in Isopar L at ambient temp. Aqueous phase: HNO3= 1M, 137Cs and 85Sr tracers

  10. Extraction of Cs and Sr with the New Mixed Solvent at Various TemperaturesOrganic phase: 0.15M DtBuCH18C6, 0.007M BOBCalixC6, 0.75M Cs-7SB modifier in Isopar LAqueous phase: HNO3= 1M, 137Cs and 85Sr tracers CSSX Solvent: Temp. DCs 10oC 46 SREX Solvent: Temp.DSr 10oC 2 New Mixed Solvent: Temp. DCs DSr 10oC 20 16

  11. Contact # DCs DSr  1 22 21 2 23 22 3 20 20 4 21 21 5 21 21 Strip #DCs DSr 1 0.42 0.035 2 0.21 0.006 3 0.24 nd 4 0.29 nd Sequential Forward and Back Extraction of New Mixed Solvent at 15 ºC (1.0 M HNO3) (0.01 M HNO3)

  12. Simulated Dissolved Nuclear Fuel Solution Traced with 137Cs and 85Sr in 1M HNO3 at Varied Temperature Simulant component concentrations, (M) HNO3 1.00 Sr 2.0E-03 Cs 4.1E-03 Rb 1.0E-03 Zr 1.1E-02 Ba 3.7E-03 La 2.2E-03 Ce 4.3E-03 Nd 7.2E-03 Sm 5.0E-03 Gd 2.6E-04 Eu 1.4E-04 Y 1.4E-03

  13. Conclusions • New Mixed Solvent is an efficient cesium and strontium extractant for simultaneous removal from acidic LWR simulants • Synergistic Strontium Extraction: DSr= 6 at 15oC • Maintains high Cesium Extraction: DCs= 12 at 15oC • Forward distributions increase at lower temperature • Back extractions using 0.01M HNO3 indicates effective stripping ( likely improves with increased temp.)

  14. Future Work • Goals for FY-05 • Optimize extractant concentrations • Continue forward distribution studies • Nitric acid extraction • 15 o C for flowsheet is reasonable • Continue stripping studies • Temperature dependence study • Study effects of macro levels of elements • Develop a process flowsheet to support testing

  15. Acknowledgments We wish to thank Bruce A. Moyer, Laetitia H. Delmau and Peter V. Bonnesen at Oak Ridge National Laboratory for the calixarene-crown ether, the modifier and helpful discussions. This research was sponsored by the U.S. Department of Energy, Office of Nuclear Energy, Science and Technology under DOE Idaho Operations Office contract DE-AC07-99ID13727

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