Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT) (방사성폐기물학회지)

Korean Radioactive Waste Society (한국방사성폐기물학회)
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Precipitation behaviors of Cs and Re(/Tc) by NaTPB and TPPCl from a simulated fission products-$(Na_2CO_3-NaHCO_3)-H_2O_2$ solution

모의 FP-$(Na_2CO_3-NaHCO_3)-H_2O_2$ 용액으로부터 NaTPB 및 TPPCl에 의한 Cs 및 Re(/Tc)의 침전 거동

  • Received : 2010.01.26
  • Accepted : 2010.04.02
  • Published : 2010.06.30
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Abstract

In this study, the removal of Cs and Tc from a simulated fission products (FP) solution which were co-dissolved with U during the oxidative-dissolution of spent fuel in a mixed carbonate solution of $(Na_2CO_3-NaHCO_3)-H_2O_2$ was investigated by using a selective precipitation method. As Cs and Tc might cause an unstable behavior due to the high decay heat emission of Cs as well as the fast migration of Tc when disposed of underground, it is one of the important issues to removal them in views of the increase of disposal safety. The precipitation of Cs and Re (as a surrogate for Tc) was examined by introducing sodium tetraphenylborate (NaTPB) and tetraphenylphosponium chloride (TPPCl), respectively. Precipitation of Cs by NaTPB and that of Re by TPPCl were completed within 5 minutes. Their precipitation rates were not influenced so much by the temperature and stirring speed even if they were increased by up to $50^{\circ}C$ and 1,000 rpm. However, the pH of the solution was found to have a great influence on the precipitation with NaTPB and TPPCl. Since Mo tends to co-precipitate with Re at a lower pH, especially, it was effective that a selective precipitation of Re by TPPCl was carried out at pH of above 9 without co-precipitation of Mo and Re. Over 99% of Cs was precipitated when the ratio of [NaTPB]/[Cs]>1 and more than 99% of Re, likewise, was precipitated when the ratio of [TPPCl]/[Re]>1.

본 연구는 $H_2O_2$가 함유된 ($Na_2CO_3-NaHCO_3$) 혼합 탄산염 계에서 사용후핵연료를 산화용해할 시 U과 함께 공용해 되는 Cs, Te, Tc, Mo 등의 핵분열생성물로부터 Cs과 Tc의 선택적 침전 제거 거동을 규명하였다. Cs과 Tc은 각각 장수명 핵종으로 지하에서의 빠른 핵종 이동성과 고방열성 등으로 최종 처분 시 처분 환경을 저해하는 핵종으로 처분 안전성 제고 측면에서 이들의 제거는 중요한 과제 중의 하나이다. Cs과 Re (Tc 대용원소)의 선택적 침전제로는 각각 NaTPB, TPPCl를 선정하였으며, NaTPB에의한 Cs 침전 및 TPPCl에 의한 Re 침전 모두 5분 이내로 매우 빠르게 이루어졌으며, 온도를 $50^{\circ}C$, 교반속도를 1000 rpm 까지 증가시켜도 이들의 침전 속도에는 별 영향이 없었다. NaTPB 침전 및 TPPCl 침전에 있어 가장 중요한 요인은 침전 용액의 pH 이며, 특히 TPPCl에 의한 Re의 선택적 침전의 경우 낮은 pH 에서 Mo가 Re과 공침되므로 pH 9 이상에서 수행하는 것이 효과적이다. 그리고 [NaTPB]/[Cs] 및 [TPPCl]/[Re]의 몰 농도 비 1 이상에서 Cs 및 Re을 각각 99% 이상 선택적으로 침전 제거할 수 있었다.

Keywords

References

  1. Report to Congress, "DOE spent nuclear fuel recycling program plan", US Department of Energy (2006).
  2. "The challenges and directions for nuclear energy policy in Japan, Japan's nuclear energy national plan", Ministry of Economy, Trade and Industry (METI), Japan (2006).
  3. K. W. Kim, J. K. Lim, D. Y. Chung, H. B. Yang, K. C. Song, K. Y. Jee and E. H. Lee, "A process for the recovery of uranium from spent nuclear fuel by using a high alkaline carbonate solution", Korea Patent Application No. 38599 (2008)., "Process for recoverying isolated uranium from spent nuclear fuel using a highly alkaline carbonate solution", US Patent Application No. 12/337,599 (2008).
  4. K. W. Kim, D. Y. Chung, H. B. Yang, J. K. Lim, E. H. Lee, K. C. Song and K. S. Song, "A conceptual process study for recovery of uranium alone from spent nuclear fuel by using high alkaline carbonate media", Nucl. Tech., 166, pp. 170-179 (2009).
  5. S. Rollin, K. Spahiu and U. B. Eklund, "Determination of dissolution rates of spent fuel in carbonate solutions under different redox conditions with a flow-through experiment", J. Nucl. Mater., 297, pp. 231-243 (2001). https://doi.org/10.1016/S0022-3115(01)00645-6
  6. F. Clarens, J. de Pablo, I. Casa, J. Gimenez, M. Rovira, J. Merino, E. Cera, J. Bruno, J. Quinones and A. M. Esparza, "The oxidative dissolution of unirradiated $UO_2$ by hydrogen peroxide as a function of pH", J. Nucl. Mater., 35, pp. 225-231 (2005).
  7. N. Asanuma, M. Harada, M. Nogami, K. Suzuki, T. Kikuchi, H. Tomiyasu and Y. Ikeda, "Anodic dissolution of $UO_2$ Pellet containing simulated fission products in ammonium carbonate solution", J. Nucl. Sci. Technol., 43(3), pp. 255-262 (2006). https://doi.org/10.3327/jnst.43.255
  8. S. M. Peper, L. F. Brodnax, S. E. Field, R. A. Zehnder, S. N. Valdez and W. H. Runde, "Kinetic study of the oxidative dissolution of $UO_2$ in aqueous carbonate media", Ind. Eng. Chem. Res., 43, pp. 8188-8193 (2004). https://doi.org/10.1021/ie049457y
  9. E. H. Lee, J. K. Lim, D. Y. Chung, H. B. Yang and K. W. Kim, "The characteristics of an oxidative dissolution of simulated fission product oxides in $(NH_4)_2CO_3$ solution containing $H_2O_2$", J. Korean Radioactive Waste Soc., 7(2), pp. 93-100 (2009).
  10. E. H. Lee, J. K. Lim, D. Y. Chung, H. B. Yang, J. H. Yoo and K. W. Kim, "The oxidative-dissolution behaviors of fission products in a $Na_2CO_3-H_2O_2$ solution", J. Radioanal. Nucl. Chem.. 281, pp 339-346 (2009). https://doi.org/10.1007/s10967-009-0018-6
  11. Y. Kondo, M. Kubota, T. Abe and K. Nagato, "Development of partitioning method: Recovery and utilization of useful elements in SF (Literature survey)", JAERI-M 91-147, (1991).
  12. Y. Asano, N. Asanuma, T. Ito, M. Kataoka, S. Fujino, T. Yamamura, W. Sugiyama and H. Tomiyasu, "Study on a nuclear fuel reprocessing system based on the precipitation method in mild aqueous solutions", Nucl. Technol., 120, pp. 198-210 (1997).
  13. N. Asanuma, M. Harada, Y. Ikeda and H. Tomiyasu, "New approach to nuclear fuel reprocessing in non-acidic aqueous solutions", J. Nucl. Sci. Technol. 38(10), pp. 866-871 (2001). https://doi.org/10.3327/jnst.38.866
  14. J. A. Dean, "Lange's Handbook of Chemistry", 12th Edition, McGraw-Hill Book Company. (1979).
  15. R. A Peterson, J. O. Burgess, D. D. Walker, D. T. Hobbs, S. M. Serkiz, M. J. Barnes and A. R. Jurgensen, "Decontamination of high-level waste using a continuous precipitation process", Sep. Sci. Tech., 36(5&6), pp. 1307-1321 (2001). https://doi.org/10.1081/SS-100103651
  16. J. C. Fanning, "The solubilities of the alkali metal salts and the precipitation of Cs+ from aqueous solution", Coord. Chem. Rev., 140, pp. 27-36 (1995). https://doi.org/10.1016/0010-8545(94)01123-S
  17. S. M. Ponder and T. E. Mallouk, "Recovery of ammonium and cesium ions from aqueous waste streams by sodium tetraphenylborate", Ind. Eng. Chem. Res., 38, pp. 4007-4010 (1999).
  18. P. Blazy, E. A. Jdid, A. Floreancig and B. Mottet, "Selective recovery of rhenium from gas-scrubbing solutions of Molybdenite roasting using direct precipitation and separation on resins", Sep. Sci. Technol., 28(11&12), pp. 2073-2096 (1993). https://doi.org/10.1080/01496399308016735
  19. D. D. Walker and M. A. Ebra, "Nuclear waste solution", US Pat. No. 4654173 (1987).
  20. S. Aldridge, P. Warwick, N. Evans and S. Vines, "Degradation of tetraphenylphosphonium bromide at high pH and its effect on radionuclide solubility", Chemosphere, 66, pp. 672- 676 (2007). https://doi.org/10.1016/j.chemosphere.2006.07.088
  21. C. F. Baes, Jr. and R. E. Mesmer, "Th hydrolysis of cations", Robert E. Krieger Pub. Company, Malabar, Florida (1986).
  22. J. H. Park, Y. H. Yoo, W. M. Chung, K. I. Lee, M. S. Woo and D. S. Whang, "A review on the process technology for Mo-99 production", KAERI/AR-401/94 (1994).