Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
권호 표지
DOI QR코드

DOI QR Code

COMPARISON BETWEEN EXPERIMENTALLY MEASURED AND THERMODYNAMICALLY CALCULATED SOLUBILITIES OF UO2 AND THO2 IN KURT GROUND WATER

  • Published : 2009.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

Solubility of a radionuclide is important for defining the release source term of a radioactive waste in the safety and performance assessments of a radioactive waste repository. When the pH and redox potential of the KURT groundwater were changed by an electrical method, the concentrations of uranium and thorium released from $UO_2$(cr) and $ThO_2$(cr) at alkali pH(8.1 ${\sim}$ 11.4) and reducing potential (Eh < -0.2 V) conditions were less than $10^{-7}mole/L$. Unexpectedly, the concentration of tetravalent thorium is slightly higher than that of uranium at pH = 8.1 and Eh= -0.2 V conditions, and this difference may be due to the formation of hydroxide-carbonate complex ions. When $UO_2$(s) and $UO_2$(am, hyd.), and $ThO_2$(s) and $Th(OH)_4(am)$ were assumed as solubility limiting solid phases, the concentrations of uranium and thorium in the KURT groundwater calculated by the PHREEQC code were comparable to the experimental results. The dominating aqueous species of uranium and thorium were presumed as $UO_2(CO_3)_3^{4-}$ and $Th(OH)_3CO_3^-$ at pH = 8.1 ${\sim}$ 9.8, and $UO_2(OH)_3^-$ and $Th(OH)_4(aq)$ at pH = 11.4.

Keywords

References

  1. D. K. Keum, M. H. Baik and P. S. Hahn, 'Speciation and Solubility of Major Actinides under the Deep Groundwater Conditions of Korea,' J. Korean Nuclear Society, 43(5), 517 (2002)
  2. M. H. Baik, S. Y. Lee, J K. Lee, S. S. Kim, C. K. Park and J. W. Choi, 'Review and Compilation of Data on Radionuclides Migration and Retardation for the Performance Assessment of a HLW Repository in Korea,' Nucl. Eng. Technol., 40(7), 593 (2008) https://doi.org/10.5516/NET.2008.40.7.593
  3. I. G. McKinley, W. R. Alexander, A. Gautschil and N. Waber, 'An Approach to Validation of Solubility Databases for Performance Assessment,' Radiochim. Acta, 82, 407 (1998)
  4. KAERI, Progress Rreport on the R&D Program for the Disposal of HLW in Korea: Appendix; Korea Atomic Energy Research Institute: Daejeon, Korea (2002)
  5. G. R. Choppin, “Actinide Speciation in Aquatic Systems,” Marine Chemistry, 99, 83 (2006) https://doi.org/10.1016/j.marchem.2005.03.011
  6. IAEA, “Geochemistry of Long-Lived Transuranic Actinides and Fission Products,” IAEA-TECDOC-637, International Atomic Energy Agency (1992)
  7. D. L. Parkhurst and C. A. J. Appelo, 'User's Guide to PHREEQC (Version 2) - A Computer Program for Speciation, Batch-Reaction, One-Dimensional Transport and Inverse Geochemical Calculations," Water-Resources Investigations Report 99-4259, Water Resources of the United States (1999)
  8. OCRWM, “Dissolved Concentration Limits of Radioactive Elements,” ANL-WIS-MD-000010 REV 02, Office of Civilian Radioactive Waste Management (2003)
  9. W. Hummel, U. Berner, E. Curti, F. J. Pearson and T. Thoenen, Nagra/PSI Chemical Thermodynamic data base 01/01, Universal Publishers, Florida, USA (2002)
  10. K. M. Knupka and R. J. Serne, “Geochemical Factors Affecting the Behavior of Antimony, Cobalt, Europium, Technetium, and Uranium in Vadose Sediments,” PNNL- 14126, Pacific Northwest National Laboratory ( 2002)
  11. L. O. Werme and K. Spahiu, “Direct Disposal of Spent Fuel: Comparison Between Experimental and Modeled Actinide Solubilities in Natural Waters,” J. Alloys and Compounds, 271, 194 (1998) https://doi.org/10.1016/S0925-8388(98)00053-X
  12. Sergei Butorin, Kaija Ollila and Yngve Albinsson, “Reduction of Uranyl Carbonate and Hydroxyl Complexes and Neptunyl Carbonate Complexes Studied with Chemical- Electrochemical Methods and RIXS Spectroscopy,” POSIVA 2004-01, Posiva, Finland (2004)
  13. M. Altmaier, V. Neck, R. Muller and Th. Fanghanel, “Solubility of ThO2.xH2O(am) in Carbonate Solution and the Formation of Ternary Th(IV) Hydroxide-Carbonate Complexes,” Radiochim. Acta, 93, 83 (2005) https://doi.org/10.1524/ract.93.2.83.59420
  14. B. Wierczinski, S. Helfer, M. Ochs and G. Skarnemark, “Solubility Measurements and Sorption Studies of Thorium in Cement Pore Water,” J. Alloy and Compounds, 271, 272 (1998) https://doi.org/10.1016/S0925-8388(98)00069-3
  15. S. Y. Lee, M. H. Baik and W. J. Cho, “A Study on the Mineralogical and Geochemical Propertiesof Rocks and Fractures/Faults in KURF,” KAERI/TR-3140/2006, Korea Atomic Energy Research Institute (2006)
  16. F. J. Mompean, M. Illemassene, C. Domenech-Orti and K. B. Said, Chemical Thermodynamics 5: Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, Elsevier, OECDNEA, Orsay, France (2003)
  17. S. Takeda, S. Shima, H. Kimura and H. Matsuzuru, “The Aqueous Solubility and Speciation Analysis for Uranium, Neptunium and Selenium by the Geochemical Code (EQ3/6),” JAERI Research 95-069, Japan Atomic Energy Research Institute (1995)
  18. I. Puigdomenech and J. Bruno, “Modeling Uranium Solubilities in Aqueous Solutions: Validation of a Thermodynamic Data Base for the EQ3/6 Geochemical Codes,” SKB-TR-88-21, Swedish Nuclear Fuel and Waste Management Co (1988)
  19. I. G. McKinley and D. Savage, 'Comparison of Solubility Database Used for HLW Performance Assessment,' J. Contaminant Hydrology, 21, 335 (1996) https://doi.org/10.1016/0169-7722(95)00057-7
  20. V. Neck and J. I. Kim, “Solubility and Hydrolysis of Tetravalent Actinides,” Radiochim. Acta, 89, 1 (2001) https://doi.org/10.1524/ract.2001.89.1.001
  21. W. Runde, S. D. Conradson, D. W. Efurd, N. P. Lu, C. E. vanPelt and C. D. Tait, 'Solubility and Sorption of Redox- Sensitive Radionuclides (Np, Pu) in J-13 Water from the Yucca Mountain Site: Comparison Between Experiment and Theory,' Applied Geochemistry, 17(7), 837 (2002) https://doi.org/10.1016/S0883-2927(02)00043-4
  22. B. Grambow, A. Loida, A. M. Esparza, P. D. Arocas, J. de Pablo, J. L. Paul, G. Marx, J. P. Glatz, K. Lemmens, K. Ollila and H. Christensen., “Long-Term Safety of Radioactive Waste Disposal: Source Term for Performance Assessment of Spent Fuel as a Waste Form. Final Report,” FZKA- 6420, Forschungszentrum Karlsruhe, Germany (2000)
  23. D. Rai, A. Felmy and J. Ryan, “Uranium(IV) Hydrolysis Constant and Solubility Product of UO2·H2O(am),” Inorg. Chem., 29, 7852 (1990) https://doi.org/10.1021/ic00327a022
  24. I. Grenthe, J. Fuger, R. J. M. Konings, R.J. Lemire, A. B. Muller, C. Nguyen-Trung and H. Wanner, Chemical Thermodynamics of Uranium, Elsevier, Amsterdam, Netherlands (1992)
  25. M. Chandratillake, D. P. Trivedi, M. G. Randall, P. N. Humphreys and E. J. Kelly, “Criteria for Compilation of a Site-Specific Thermodynamic Database for Geochemical Speciation Calculations,” J. Alloys and Compounds, 271, 821 (1998) https://doi.org/10.1016/S0925-8388(98)00226-6