Idaho National Engineering and Environmental Laboratory 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

Idaho National Engineering and Environmental Laboratory 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.

Idaho National Engineering and Environmental Laboratory 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 M BOBCalixC M Cs-7SB modifier M TOA Isopar L SREX Solvent 0.15 M DtBuCH18C6 1.2 M TBP Isopar L CSSX Solvent M BOBCalixC M Cs-7SB modifier M TOA Isopar L SREX mixture components combined and stirred for one hour CSSX solvent received already prepared SREX mixture components combined and stirred for one hour CSSX solvent received already prepared Aqueous samples consisted of: 137 Cs tracer, with carrier ( M CsNO 3 ) in HNO 3 85 Sr tracer, with carrier (0.001 M Sr(NO 3 ) 2 in HNO 3 Aqueous samples consisted of: 137 Cs tracer, with carrier ( M CsNO 3 ) in HNO 3 85 Sr tracer, with carrier (0.001 M Sr(NO 3 ) 2 in HNO 3

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

Idaho National Engineering and Environmental Laboratory Extraction of Sr with SREX (Strontium Extraction) Organic phase: 0.15M DtBuCH18C6, 1.2M TBP in Isopar L at ambient temp. (23 o C ± 3 o ) Aqueous phase: HNO 3 = varied concentrations, 85 Sr tracer Dist. at 1M HNO 3 : Sr = 0.7 (Consistent with previous work, Dietz et al., 1995) Dist. at 1M HNO 3 : Sr = 0.7 (Consistent with previous work, Dietz et al., 1995)

Idaho National Engineering and Environmental Laboratory 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: HNO 3 = varied concentrations, 137 Cs tracer Dist. at 1M HNO 3 : Cs = 7.9 Dist. at 1M HNO 3 : Cs = 7.9

Idaho National Engineering and Environmental Laboratory 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 L Aqueous phase: HNO 3 = varied conc., 137 Cs and 85 Sr tracers

Idaho National Engineering and Environmental Laboratory 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 to 0.180M in Isopar L Aqueous phase: HNO 3 = 1M, 137 Cs and 85 Sr tracers

Idaho National Engineering and Environmental Laboratory 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: HNO 3 = 1M, 137 Cs and 85 Sr tracers

Idaho National Engineering and Environmental Laboratory Extraction of Cs and Sr with the New Mixed Solvent at Various Temperatures Organic phase: 0.15M DtBuCH18C6, 0.007M BOBCalixC6, 0.75M Cs-7SB modifier in Isopar L Aqueous phase: HNO 3 = 1M, 137 Cs and 85 Sr tracers CSSX Solvent: Temp. D Cs 10 o C 46 SREX Solvent: Temp. D Sr 10 o C 2 New Mixed Solvent: Temp. D Cs D Sr 10 o C CSSX Solvent: Temp. D Cs 10 o C 46 SREX Solvent: Temp. D Sr 10 o C 2 New Mixed Solvent: Temp. D Cs D Sr 10 o C 20 16

Idaho National Engineering and Environmental Laboratory Sequential Forward and Back Extraction of New Mixed Solvent at 15 ºC Contact # D Cs D Sr Contact # D Cs D Sr Strip # D Cs D Sr nd nd Strip # D Cs D Sr nd nd (0.01 M HNO 3 )(1.0 M HNO 3 )

Idaho National Engineering and Environmental Laboratory Simulated Dissolved Nuclear Fuel Solution Traced with 137 Cs and 85 Sr in 1M HNO 3 at Varied Temperature Simulant component concentrations, (M) HNO 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 Simulant component concentrations, (M) HNO 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

Idaho National Engineering and Environmental Laboratory Conclusions  New Mixed Solvent is an efficient cesium and strontium extractant for simultaneous removal from acidic LWR simulants  Synergistic Strontium Extraction: D Sr = 6 at 15 o C  Maintains high Cesium Extraction: D Cs = 12 at 15 o C  Forward distributions increase at lower temperature  Back extractions using 0.01M HNO 3 indicates effective stripping ( likely improves with increased temp.)

Idaho National Engineering and Environmental Laboratory 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

Idaho National Engineering and Environmental Laboratory 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