1. Am and Cm Absorption Studies on TEVA Resin from Metal Nitrate Matrices
Narek Gharibyan1, Ashlee Crable1, Steffen Happel2, Ralf Sudowe1
1University of Nevada, Las Vegas
2Triskem International, Bruz, France
Glenn T. Seaborg Award for Nuclear Chemistry: Symposium in Honor of Kenton J. Moody
237th ACS Meeting
Salt Lake City, Utah

2. Outline Overview Experimental Design Results Conclusion Future Work
Project introduction
Objectives
TEVA resin & previous results
Experimental Design
Results
k’ value
LiNO3, NaNO3, KNO3, Mg(NO3)2, Ca(NO3)2 and Al(NO3)3
Metal and nitrate effects
Summary
Conclusion
Future Work
Acknowledgement

3. Neutron Capture Cross-Section for 241Am
Project Goal: neutron capture cross-section and isomeric ratio determination for:
In collaboration with LANL and UCB
141 y
(n,γ) IT
241Am
16.02 h β-
242Am
162.8 d
242Cm

4. Neutron Capture Cross-Section for 241Am
Decay scheme of 241Pu
Major interest from NNSA and weapons laboratories
Weapons grade plutonium
Contains ~0.5% 241Pu
(0.65 %1; 0.54 %2)
1Keegan, R.P., Gehrke, R.J., Applied Radiation and Isotopes 59, (2003)
2Condit, R.H., Plutonium Dispersal in Fires: Summary of What is Known. 1993, Lawrence Livermore National Laboratory

5. Group Objective
Development of efficient separation method for separating milligram quantities of Am from trace amounts of Cm
Overlapping interest with the fuel cycle and nuclear forensics

6. Am/Cm Separation
Oxidation of Am(III) to Am(V) or Am(VI) to enhance separation
Highly dependent on stability of the higher oxidation states
Reduction due to acid matrix or organic solvents
Separation without oxidation of Am
Some of the current methods:
Tertiary pyridine resin with nitric acid-methanol system
Cation exchange with HIB system
Extraction chromatography: high molecular weight quaternary ammonium nitrate (Aliquat-336 nitrate)
LiNO3 system
Separation factor3 of 2.7 at 3.6 M
Separation factor4 of >105 at 3.6 M
3Horwitz, E.P., Bloomquist, C.A.A., Orlandini, K.A., Henderson, D.J., Radiochim. Acta 8, (1967)
4Borkowski, M., Fuks, L., Nukleonika 33, 10-12, (1988)

7. Trialkyl, methylammonium nitrate
Resin - TEVA
TEVA resin from Eichrom
Active component: high molecular weight quaternary ammonium nitrate (or chloride) R R
N + NO3- R
CH3
R = C8H17 and C10H21
Trialkyl, methylammonium nitrate

8. Previous Results - TEVA

9. Primary Objective
What effects do metals have on absorption properties of Am and Cm in nitrate matrices?
Li+, Na+, K+, Ca2+, Mg2+ and Al3+

10. Experimental Design Preconditioning resin
~100 mg of resin
2.000 mL of specific NO3- solution
Mix for 1 hour
Addition of Am-241 or Cm-244 stock solution
0.500 mL stock solution added (in 0.01 M HNO3)
Filtration and activity determination
1.3 mL aliquot filtered using PTFE filter
1.000 mL analyzed with LSC
Example: 2.00 M LiNO3 – M HNO3
*For statistical purposes, five trials were performed at each condition

11. Results
Absorption expressed in terms of k’ values, number of free column volumes to peak maximum5
k’ value can be determined from Dw
Dependent on the resin (correction factor)6
Resin
Correction Factor (F)
TEVA
0.526
5Horwitz, E.P., Chiarizia, R., Dietz, M.L., Solvent Extr. Ion Exch. 10, (1992)
6Eichrom Website: “Extraction Chromatography of Actinides and Selected Fission Products: Principles and Achievement of Selectivity” August 2008

12. Results – TEVA from LiNO3
Highest SF M
*Error bars show standard deviation from five measurements

13. Results – TEVA from NaNO3
Highest SF M

14. Results – TEVA from KNO3
Highest SF -

15. Results – TEVA from Mg(NO3)2
Highest SF M

16. Results – TEVA from Ca(NO3)2
Highest SF M

17. Results – TEVA from Al(NO3)3
Highest SF M

18. Results – Am on TEVA: [Metal Nitrate]
[X(NO3)Y]

19. Results – Am on TEVA: [Nitrate]

20. Results – Cm on TEVA: [Nitrate]

21. Summary Extraction species are anionic Am and Cm nitrato species
Am(NO3)4- and Cm(NO3)4-
Formation of anionic species evident >2.00 M nitrate
k’ value for Am and Cm increase at higher nitrate concentrations
Higher absorption for Am compared to Cm, SF~2.5
From literature, SF of 2.7 (Horwitz) and >105 (Borkowski)

22. Summary Cation effects: two groups
Group #A (Li+, Mg2+, Al3+): metal cation radius7 (pm) 67-90
Group #B (Na+, Ca2+): metal cation radius7 (pm)
7Wulfsberg, G. Principles of Descriptive Chemistry; Brooks/Cole Publishing, Monterey, CA, 1987, p. 25

23. Conclusion
Two different possible mechanism for understanding metal cation effect on Am/Cm absorption to TEVA resin:
1. More nitrates interact with larger cation
Effectively reducing the nitrate concentration in solution, reduces the formation of anionic actinide nitrato complexes at given nitrate concentration
2. Larger cations prevent interaction with active sites on the resin
Larger cations more effectively shield the anionic actinide nitrato species from binding to the active sites on the resin
By formation of secondary positive layer (positive) around the anionic species

24. Future Work Repeat Li and Na systems with solvent extraction method
Aliquat-336 available from Sigma-Aldrich
Should provide information on whether or not cations shield extraction species from active sites on the resin
Dynamic column studies with TEVA resin
Reproduce results from batch experiments

25. Acknowledgements Ralf Sudowe David Vieira (LANL)
Heino Nitsche (UCB/LBNL)
Chris Klug
Tom O’Dou
Trevor Low
UNLV Radiochemistry Group
Funding for this work was provided by the DOE under contract DE-FG52- 06NA27480 through subcontract SA with UC Berkeley

26. Questions?