Patricia Paviet-Hartmann
Research Associate Professor
Ph.D. Radiochemistry,
University Paris XI, France - 1992
| Research Area: | Radiochemistry, Actinide Chemistry, Chemical and Radiochemical Aspect of the Nuclear Fuel Cycle |
| Student Experience required for research: | Chem 111, Chem 112 |
| Student Experience gained from research: | Separation Techniques for Actinides/Radionuclides, Speciation of actinides via spectroscopy (UV Vis spectrophotometry, Laser spectroscopy), Integrated Repository Sciences, Behavior of actinides under nuclear repository conditions, Nuclear Fuel Cycle Processes (Purex, Urex, Diamex, Sanex, Truex) |
| Ideal Preparation for: | Nuclear Industry, R&D in Actinide/Radionuclide Chemistry. |
Research Description
1) Integrated Repository Sciences _ Spectrophotometric Investigation of U(VI) Hypochloro Complexation in the Ca(ClO)2/NaClO4 System
The option of a nuclear waste repository in a deep salt formation attracts the attention of the international environmental community. A systematic investigation of actinide solution chemistry in brines in order to model their behavior in natural multicomponent brines of high concentration is underway. The US's first geologic repository for radioactive waste is being excavated in southeastern New Mexico at the WIPP. Post closure radioactive release scenarios from the WIPP often involve hydrologic transport of radionuclides through the overlying Rustler Formation, in the Culebra Dolomite Member, a NaCl type water. Consequently, the knowledge of uranium solution chemistry in brines is important in understanding its chemical behavior and requires additional comprehension concerning the interaction between UO22+ and hypochlorite ion OCl-. New data concerning the dioxouranium (VI) hypochloro complexes formation in Ca(ClO)2/NaClO4 solution will be reported through this research investigation.
2) Catalyzing Effects of Plutonium/Uranium on the Chemical Degradation of TBP and Degradation Products in a Nitric Acid Medium
Tributylphosphate (TBP) has been utilized in conjunction with nitric acid and various diluents for the past fifty years to separate actinides at nuclear processing facilities. The degradation of TBP and subsequent exothermic oxidation of the associated by-products by nitric acid introduces the risk of a runaway reaction and related over-pressurization and/or gas explosion event due to the property of the reactions and the off-gases produced. This risk exists in process units within the PUREX process that may contain these products and reach elevated temperatures.
TBP degradation may proceed by (1) Hydrolysis (acid catalyzed): the reaction of TBP with H2O/H+ yields butanol (BuOH) and HDBP. Butanol may then react to form butyl nitrate (BuNO3), carboxylic acids (primarily acetic acid, propionic acid and butyric acid) and gases, (2) Dealkylation: the reaction of TBP with nitric acid yields butyl nitrate and HDBP. Butyl nitrate may then react to form carboxylic acids and gases (the reaction may also lead to butanol)., and (3) Pyrolysis: TBP can be decomposed into butene, phosphoric esters and phosphoric acid.
A series of experiments to determine (1) the stability of BuOH in the presence of U(VI), (2) the stability of BuNO3 in the presence of U(VI,) (3) the stability of BuOH in the presence of Pu(IV), (4) the stability of BuONO2 in organic medium TBP/HPT in the presence of Pu(IV) will obtain kinetic data, thermodynamic data, distribution coefficients, and Henry's coefficients for TBP/butanol/butyl nitrate systems in a Plutonium/Uranium nitric acid medium. The objectives of these experiments are to acquire data that will permit a kinetic based understanding of TBP decomposition.
3) Investigation of novel organic/inorganic hybrid chelating resins/ adsorbents for minor actinides (Am, Cm) separation
In the AFCI program, the separation of the trivalent actinides Americium (Am) and Curium (Cm) from the trivalent lanthanides has been identified as an area of particular interest. The removal of the lanthanides from the trivalent actinides or minor actinides (Am, Cm) is necessitated to avoid the strong absorption of thermalized neutrons by the lanthanides. Furthermore a fuel containing only Am would ease the demands on a reactor for transmutation. Separation and storage of the Cm, and reintroduction into the fuel as Pu daughters is a transmutation option that can be explored if a suitable method for the separation of Cm from Am is obtained. Furthermore, the removal of Cm would reduce difficulties in fuel fabrication. A number of techniques and reagents have been developed: (1) the separation of trivalent actinides and lanthanides using CMPO or TODGA, (2), separation of trivalent actinides from lanthanides using CYANEX 301 or R-BTP
Different avenues will be investigated for the ultimate separation of Am(III) from Cm(III) Avenue 1: During the process of separation of Am from Cm contained in an aqueous nitric solution, the initial solution will undergo oxidation at ambient temperature in the presence as an example of phosphoric acid or phosphate ions at a determined concentration in such a way as to pass the americium at valence state VI. The aqueous phase containing Am(VI) and Cm(III) will be brought into contact with a slightly reducing organic solvent having a high affinity for Am(VI) in such a way as to extract Am(VI) in the organic phase. This high affinity solvent will have to be determined based on the Am(VI) chemistry. The organic phase containing Am (VI) will be washed, followed by the re-extraction of Am(VI) in the organic phase by means of an aqueous solution. Avenue 2: Specific extraction of Am(III) from Cm(III) using tertiary pyridine-type resin. The separation system is based on the chromatography using a tertiary pyridine-type resin.
Investigations on real effluents will be undertaken, the determination of solvent/diluent will be explored, the decontamination factor as well as distribution coefficient of Am and Cm will be determined. Tolerance of the resins towards irradiation will be performed at the Idaho Accelerated Center. If successful, we will have demonstrated (1) a specific and selective extraction of Am (III) from Cm(III), (2) the radiation tolerance of the macrocompound towards radiation.
Journal/Book Publications
"Thermal Stability and Safe Venting of the tri-n-butyl phosphate-nitric acid-water ("Red Oil" System. III - Predictions of Thermal Stability Boundaries and Required Vent Size, M. Epstein, H. K. Fauske, C. F. Askonas, M. Vial, P. Paviet-Hartmann, S. Raman, submitted to Nuclear Technology, (2007).
"Thermal Stability and Safe Venting of the tri-n-butyl phosphate-nitric acid-water ("Red Oil") System. II - Experimental data on reaction self-heat rates and gas production and their correlation", M. Epstein, H. K. Fauske, C. F. Askonas, M. Vial, P. Paviet-Hartmann, S. Raman, submitted to Nuclear Technology, (2007).
"Thermal Stability and Safe Venting of the tri-n-butyl phosphate-nitric acid-water ("Red Oil") System. I - Two Layer Systems Mass Transfer Theory", M. Epstein, H. K. Fauske, C. F. Askonas, M. Vial, P. Paviet-Hartmann, S. Raman, submitted to Nuclear Technology, (2007).
"Chemical speciation of heterogeneously reduced Pu in synthetic brines", Ding, Mei; Conca, James L.; den Auwer, Christophe; Gabitov, Rinat I.; Hess, Nancy J.; Paviet-Hartmann, Patricia; Palmer, Phillip D.; LoPresti, Vin; Conradson, Steven D., Radiochimica Acta, 94(5), 249-259, (2006).
"Charge distribution and local structure and speciation in the UO2+x and PuO2+x binary oxides for x˛0.25", Conradson Steven D.; Begg Bruce D.; Clark David L.; Den Auwer Christophe; Ding Mei; Dorhout Peter K.; Espinosa-Faller Francisco J., Gordon Pamela L., Haire Richard G. Hess, Nancy J. Hess, Ryan F., Webster Keogh D.; Lander Gerard H.; Manara Dario; Morales Luis A.; Neu Mary P.; Paviet-Hartmann Patricia; Rebizant Jean; Rondinella Vincenzo V.; Runde Wolfgang; Tait C. Drew; Veirs D. Kirk; Villella Phillip M.; Wastin Franck. Journal of Solid State Chemistry, 178(2), 521-535, (2005).
"Local and Nanoscale Structure and Speciation in the PuO2+x(H2O System", Conradson Steven D., Begg, Bruce D., Clark, David L., den Auwer Christophe, Ding Mei, Dorhout Peter K., Espinosa-Faller Francisco J., Gordon Pamela L., Haire, Richard G., Hess, Nancy J., Hess, Ryan F., Keogh, D. Webster, Morales, Luis A., Neu, Mary P., Paviet-Hartmann Patricia, Runde Wolfgang, Tait C. Drew, Veirs D. Kirk, Villella Phillip M., Journal of the American Chemical Society, 126(41), 13443-13458, (2004)
"Higher Order Speciation Effects on Plutonium L3 X-ray Absorption Near Edge Spectra", Conradson, Steven D.; Abney, Kent D.; Begg, Bruce D.; Brady, Erik D.; Clark, David L.; den Auwer, Christophe; Ding, Mei; Dorhout, Peter K.; Espinosa-Faller, Francisco J.; Gordon, Pamela L.; Haire, Richard G.; Hess, Nancy J.; Hess, Ryan F.; Keogh, D. Webster; Lander, Gerard H.; Lupinetti, Anthony J.; Morales, Luis A.; Neu, Mary P.; Palmer, Phillip D.; Paviet-Hartmann, Patricia; Reilly, Sean D.; Runde, Wolfgang H.; Tait, C. Drew; Veirs, D. Kirk; Wastin, Franck. Inorganic Chemistry, 43(1), 116-131, 2004.
"Enhancing the properties of Portland cements using supercritical carbon dioxide", Rubin, James B.; Taylor, Craig M. V.; Hartmann, Thomas; Paviet-Hartmann, Patricia, Green Chemistry Using Liquid and Supercritical Carbon Dioxide, (2003), Chap 15, 241-255, Publisher: Oxford University Press, Inc., New York, N. Y , Editor(s): DeSimone, Joseph M.; Tumas, William.
"Spectroscopic Determination of the Formation of Hypochlorous Acid, in Chloride Brine Solutions, Featuring 5 MeV Proton Beam Line Experiments", T. Hartmann, P. Paviet-Hartmann, C. Wetteland, N. Lu, Rad. Phys. Chem. , 66(5), 335-341, (2003).
"Evaluation of Speciation Technology, Cm(III) speciation in brines by Time Resolved Laser Fluorescence Spectroscopy", P. Paviet-Hartmann, Th. FanghŠnel, R. Klenze, H. Weger, Th. Kšnnecke, K.K. Park, K.H. Chung, W. Hauser, J.I. Kim, NEA/OECD proceedings, ISBN 92-64-18667-0, (2001).
"Ash cements stabilized by supercritical CO2 carbonation for tailings pond overlayer". Rubin, James B.; Taylor, Craig M. V.; Paviet-Hartmann, Patricia; Hartmann, Thomas. NATO Science Series, 1: Disarmament Technologies (2000), 28(Turning a Problem into a Resource: Remediation and Waste Management at the Sillamae Site, Estonia), 253-263, (2000).
"Supercritical CO2 Carbonation of Cemented Radioactive Waste-Forms: Influence on Leachability and Structure", T. Hartmann, P. Paviet-Hartmann, J. B. Rubin, K. E. Sickafus, Cement and Concrete Research, 29, 1359, (1999).
"The Effect of Supercritical Carbon Dioxide Treatment on the Leachability and Structure of Cemented Radioactive Waste-forms", T. Hartmann, P. Paviet-Hartmann, J.B. Rubin, M. Fitzsimmons, K.E. Sickafus, Waste Management Journal, 19, 355, (1999).
"Thermodynamics of Cm(III) in Concentrated Salt Solutions. Carbonate Complexation in 0 NaCl solution at 25 űC", Th. Fanghaenel, Th. Koennecke, H.T. Weger, P. Paviet-Hartmann, V. Neck, J.I. Kim, J. Sol. Chem., 28, 447, (1999).
"Spectrophotometric investigation of U(VI) chloride complexation in the NaCl/NaClO4 system", P. Paviet-Hartmann, M.R. Lin, Mat. Res. Soc. Symp. Proc. , 556, 977-984, (1999).
K.H. Chung, R. Klenze, K.K. Park, P. Paviet-Hartmann and J.I. Kim, Radiochimica Acta, 82, 215, (1998).
Th. Fanghaenel, H.T. Weger, Th. Koennecke, V. Neck, P. Paviet-Hartmann, E. Steinle, J.I. Kim, Radiochimica Acta, 82, 47, (1998).