Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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CsCl enrichment during solidification of molten LiCl-KCl-CsCl salt mixture

  • Received : 2024.04.06
  • Accepted : 2024.06.20
  • Published : 2024.11.25
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Abstract

Metallic alloy fuels from fast reactors will be reprocessed by a non-aqueous electrochemical technique known as electrorefining. Electrorefining of spent metal fuel results in the accumulation of heat generating fission products especially 137Cs in the electrolyte, which is a eutectic salt mixture of 44 wt% LiCl and 56 wt% KCl. The fission products need to be removed from the salt so as to reduce the decay heat load and contamination thereby facilitating reuse of the salt and minimizing waste generation. Melt crystallization technique is a simple separation process being pursued for separation of fission products. This is a single step process which utilizes the difference in solubility of fission products in the solid and liquid phase. Crystallization involves purification of a substance from a liquid mixture by solidification of the desired component. Numerical modeling of separation of CsCl from a LiCl-KCl eutectic mixture by solidification was carried out using ANSYS Fluent (19.2). The enrichment of CsCl during solidification, its distribution in molten salt and segregation time were evaluated. Further, solidification experiments were conducted using the molten salt mixture and the predicted numerical results were validated.

Keywords

Acknowledgement

The authors gracefully acknowledge the timely help rendered by the mechanical fabrication team in the fabrication of the solidification vessel, sampler. We also thank analytical chemistry lab for helping in the analysis of the salt samples by AAS and metal fuel characterization lab for carrying out the TG-DTA of salt samples.

References

  1. Nagarajan, K. Prabhakara Reddy, B. Suddasatwa Ghosh, et al., Development of Pyrochemical reprocessing for spent metal fuels, Energy Proc. 7 (2011) 431-436, https://doi.org/10.1016/j.egypro.2011.06.057.
  2. M.F. Simpson, P. Sachdev, Development of electrorefiner waste salt Disposal process for the EBR-II spent fuel Treatment Project, Nucl. Eng. and Tech. 40 (3) (2008) 175-182, https://doi.org/10.5516/NET.2008.40.3.175.
  3. M.F. Simpson, Developments in spent nuclear fuel pyroprocessing technology at Idaho National laboratory, INL/EXT-12-25124 (2012), https://doi.org/10.2172/1044209.
  4. C. Periera, B.D. Babcock, Fission product removal from molten salt using zeolite, in: 2nd International Symposium on Extraction and Processing for the Treatment and Minimization of Wastes, Arizona, 1996.
  5. Y.Z. Cho, H.C. Yang, H.C. Eun, E.H. Kim, I.T. Kim, Carbonate reaction of alkaline earth element by carbonate agent injection method, J. Nucl. Sci. Technol. 45 (5) (2008) 459-463, https://doi.org/10.1080/18811248.2008.9711455.
  6. A. Volkovich, T.R. Griffiths, R.C. Thied, Treatment of molten salt wastes by phosphate precipitation: removal of fission product elements after pyrochemical reprocessing of spent nuclear fuels in chloride melts, J. Nucl. Mater. 323 (2003) 49-56, https://doi.org/10.1016/J.JNUCMAT.2003.08.024.
  7. H.S. Lee, G.H. Oh, Y.S. Lee, et al., Concentration of CsCl SrCl2 from a simulated LiCl Waste generated by pyroprocessing by using Czochralski method, J. Nucl. Sci. Technol. 46 (4) (2009) 392-397, https://doi.org/10.1080/18811248.2007.9711545.
  8. A.V. Joshua, S. Phongikaroon, M.F. Simpson, Separation of CsCl from LiCl-KCl molten salt by cold finger melt crystallization, Nucl. Eng. Technol. 46 (3) (2014) 395-406, https://doi.org/10.5516/NET.06.2013.082.
  9. J.H. Choi, T.K. Lee, K.R. Lee, et al., Melt-crystallization monitoring system for the purification of 10 kg-scale LiCl salt waste, Nucl. Eng. Des. 326 (2018) 1-6, https://doi.org/10.1016/j.nucengdes.2017.10.016.
  10. Y.Z. Cho, G.H. Park, H.C. Yang, D.S. Han, H. Lee, I.T. Kim, Minimization of eutectic salt waste from pyroprocessing by oxidative precipitation of Lanthanides, J. Nucl. Sci. Technol. 46 10 (2009) 1004-1011, https://doi.org/10.1080/18811248.2009.9711610.
  11. https://dl.cfdexperts.net/cfd_resources/Ansys_Documentation/Fluent/Ansys_Fluent_Theory_Guide.pdf, 2021.
  12. V.R. Voller, A.D. Brent, C. Prakash, The modeling of heat, mass and solute transport in solidification systems, Int. J. Heat Mass Tran. 32 (9) (1989) 1719-1731. https://doi.org/10.1016/0017-9310(89)90054-9
  13. N. Bojan, A. Badillo, M. Profir, et al., Solidification modeling - summary. https://ec.europa.eu/research/participants/documents, 2019.
  14. G.J. Janz, N.P. Bansal, Molten salts data: Diffusion coefficients in single and multicomponent salt systems, J. Phys. Chem. Ref. Data 11 (3) (1982) 505.
  15. J. Vogel, J. Felbinger, M. Johnson, Natural convection in high temperature flat plate latent heat thermal energy storage systems, Appl. Energy 184 (2016) 184-196, https://doi.org/10.1016/j.apenergy.2016.10.001.
  16. A.N. Williams, Zone Freezing Studies for Pyrochemical Process Waste Minimization, INL/EXT-12-26425, 2012.
  17. J. Sangster, A.D. Pelton, Thermodynamic Calculation of phase diagrams of the 60 Common-Ion ternary systems containing Cations Li, Na, Rb, Cs, and Anions F,Cl, Br, I, J. Phase Equil. 12 (1991) 511-537. https://doi.org/10.1007/BF02645064
  18. K. Zang, R. Reeber, Thermal expansion of cesium halides with the CsCl structure, J. Appl. Crystallogr. 28 (3) (1995) 306-313, https://doi.org/10.1107/S0021889894014895.
  19. K. Sridharan, et al., Thermal properties of LiCl-KCl molten salt for nuclear waste separation. https://www.osti.gov/servlets/purl/1058922, 2012.
  20. C. He, C.E. Hu, T. Zhang, et al., Lattice dynamics and thermal conductivity measurements of cesium chloride by first principles investigation, Solid State Commun. 254 (2017) 31-36, https://doi.org/10.1016/j.ssc.2016.12.004.
  21. C.J. Raseman, Engineering experience at Brookhaven National laboratory in Handling fused chloride salts, Brookhaven Natl. Lab. 627 (T-192) (1960).
  22. A. Salyulev, A. Potapov, J. Chem. Eng. Data 68 (2023) 1334-1342, https://doi.org/10.1021/acs.jced.3c00090.
  23. Z. Kang, M. He, et al., A density model based on the modified quasi-chemical model and applied to the (LiCl-KCl-CsCl) liquid, CALPHAD: Comput. Coupling Phase Diagrams Thermochem. 55 (2016) 208-218, https://doi.org/10.1016/j.calphad.2016.09.005.