Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
권호 표지
DOI QR코드

DOI QR Code

Molecular dynamics study of ionic diffusion and the FLiNaK salt melt structure

  • A.Y. Galashev (Institute of High-Temperature Electrochemistry, Ural Branch of Russian Academy of Sciences)
  • Received : 2022.09.17
  • Accepted : 2022.12.21
  • Published : 2023.04.25
Download PDF
⟨ Previous Next ⟩

Abstract

In the present work, we carried out a molecular dynamics study of the kinetic properties of the FLiNaK molten salt, as well as a detailed study of the structure of this salt melt. The high value of the self-diffusion coefficient of fluorine ions is due to the large number of Coulomb repulsions between the most numerous negative ions. The calculated values of shear viscosity are in good agreement with the experimental data, as well as with the reference data obtained on the basis of finding the most reliable data. The total and partial functions of the radial distribution are calculated. According to the statistical analysis, fluorine ions have the greatest numerical diversity in the environment of similar ions, and sodium ions with the lowest representation in FLiNaK, have the least such diversity. For the subsystem of fluorine ions, the rotational symmetry of the fifth order is the most pronounced. Some of the fluorine ions form linear chains consisting of three atoms, which are not formed for positive ions. The results of the work give an understanding of the behavior molten FLiNaK under operating conditions in a molten salt reactor and will find application in future studies of this molten salt.

Keywords

Acknowledgement

This work is executed in the frame of the scientific theme of Institute of High-Temperature Electrochemistry UB RAS, number FUME-2022-0005, registration number 122020100205-5.

References

  1. P.N. Haubenre, J.R. Engel, Experience with the molten-salt reactor experiment, Nucl. Appl. Technol. 8 (1970) 118-136.  https://doi.org/10.13182/NT8-2-118
  2. M.W. Rosenthal, P.R. Kasten, R.B. Briggs, Molten-salt reactors-history, status, and potential, Nucl. Appl. Technol. 8 (1970) 107-118.  https://doi.org/10.13182/NT70-A28619
  3. L. Mathieu, D. Heuer, R. Brissot, C. Garzenne, C.L. Brun, D. Lecarpentier, E. Liatard, J.-M. Loiseaux, O. Meplan, E. Merle-Lucotte, A. Nuttin, E. Walle, J. Wilson, The thorium molten salt reactor: moving on from the MSBR, Prog. Nucl. Energy 48 (2006) 664-679.  https://doi.org/10.1016/j.pnucene.2006.07.005
  4. S. Delpech, E. Merle-Lucotte, D. Heuer, M. Allibert, V. Ghetta, C. Le-Brun, X. Doligez, G. Picard, Reactor physic and reprocessing scheme for innovative molten salt reactor system, J. Fluor. Chem. 130 (2009) 11-17.  https://doi.org/10.1016/j.jfluchem.2008.07.009
  5. B.A. Frandsen, S.D. Nickerson, A.D. Clark, A. Solano, R. Baral, J. Williams, J. Neuefeind, M. Memmott, The structure of molten FLiNaK, J. Nucl. Mater. 537 (2020), 152219. 
  6. P. Soucek, F. Lisy, R. Tulackova, J. Uhlir, R. Mraz, Development of electrochemical separation methods in molten LiF-NaF-KF for the molten salt reactor fuel cycle, J. Nucl. Sci. Technol. 42 (12) (2005) 1017-1024.  https://doi.org/10.1080/18811248.2005.9711054
  7. H.O. Nam, A. Bengtson, K. Vцrtler, S. Saha, R. Sakidja, D. Morgan, First-principles molecular dynamics modeling of the molten fluoride salt with Cr solute, J. Nucl. Mater. 449 (2014) 148-157.  https://doi.org/10.1016/j.jnucmat.2014.03.014
  8. V. Sarou-Kanian, A.-L. Rollet, M. Salanne, P.A. Madden, Diffusion coefficients and local structure in basic molten fluorides: in situ NMR measurements and molecular dynamics simulations, Phys. Chem. Chem. Phys. 11 (48) (2009) 11501-11506.  https://doi.org/10.1039/b912532a
  9. L. Langford, N. Winner, A. Hwang, H. Williams, L. Vergari, R.O. Scarlat, M. Asta, Constant-potential molecular dynamics simulations of molten-salt double layers for FLiBe and FLiNaK, J. Chem. Phys. 157 (2022), 094705. 
  10. S. Guo, J. Zhang, W. Wu, W. Zhou, Corrosion in the molten fluoride and chloride salts and materials development for nuclear applications, Prog. Mater. Sci. 97 (2018) 448-487.  https://doi.org/10.1016/j.pmatsci.2018.05.003
  11. M.P. Tosi, F.G. Fumi, Ionic sizes and born repulsive parameters in the NaCl-type alkali halides-II: the generalized Huggins-Mayer form, J. Phys. Chem. Solid. 25 (1964) 45-52.  https://doi.org/10.1016/0022-3697(64)90160-X
  12. L. Pauling, The molecular structure of the tungstosilicates and related compounds, J. Am. Chem. Soc. 51 (1929) 2868-2880.  https://doi.org/10.1021/ja01385a002
  13. J.E. Mayer, Dispersion and polarizability and the van der Waals potential in the alkali halides, J. Chem. Phys. 1 (1933) 270-279.  https://doi.org/10.1063/1.1749283
  14. D.J. Adams, I.R. McDonald, Rigid-ion models of the interionic potential in the alkali halides, J. Phys. C Solid State Phys. 7 (1974) 2761-2775.  https://doi.org/10.1088/0022-3719/7/16/009
  15. K. Meier, A. Laesecke, S. Kabelac, Transport coefficients of the Lennard-Jones model fluid. I. Viscosity, J. Chem. Phys. 121 (2004) 3671-3687.  https://doi.org/10.1063/1.1770695
  16. B.B. Karki, D. Bhattari, L. Stixrude, First-principles calculations of the structural dynamical, and electrical properties of liquid MgO, Phys. Rev. B 73 (2006), 174208. 
  17. J.A. Armstrong, P. Ballone, Computational verification of two universal relations for simple ionic liquids. kinetic properties of a model 2:1 molten salt, J. Phys. Chem. B 115 (2011) 4927-4938.  https://doi.org/10.1021/jp200229m
  18. S. Delpech, E. Merle-Locotte, D. Heuer, M. Allibert, V. Ghetta, C. Le-Brun, X. Doligez, G. Picard, Reactor physic and reprocessing scheme for innovative molten salt reactor system, J. Fluor. Chem. 130 (2009) 11-17.  https://doi.org/10.1016/j.jfluchem.2008.07.009
  19. N. Umesaki, N. Iwamoto, Y. Tsunawaki, H. Ohno, K. Furukawa, Self-diffusion of lithium, sodium, potassium and fluorine in a molten LiF + NaF + KF eutectic mixture, J. Chem. Soc., Faraday Trans. 1: Phys. Chem. Condens. Phases 77 (1981) 169-175. 
  20. A. Rudenko, A. Kataev, O. Tkacheva, Dynamic viscosity of the NaF-KF-NdF3 molten system, Materials 15 (2022) 4884. 
  21. W. Grimes, D. Cuneo, F. Blankenship, G. Keilholtz, et al., Fluid Fuel Reactors, Addison-Weslay Pub. Co., Geneva, 1958. 
  22. K.А. Tasidou, J. Magnusson, T. Munro, M.J. Assael, Reference correlations for the viscosity of molten LiF-NaF-KF, LiF-BeF2, and Li2CO3-Na2CO3-K2CO3, J. Phys. Chem. Ref. Data 48 (2019), 043102. 
  23. M. Salanne, C. Simon, P. Turq, P.A. Madden, Heat-transport properties of molten fluorides: determination from first-principle, J. Fluor. Chem. 130 (2009) 38-44.  https://doi.org/10.1016/j.jfluchem.2008.07.013
  24. J. Wu, J. Wang, H. Ni, G. Lu, J. Yu, Investigation of microscopic structure and ion dynamics in liquid Li(Na, K) eutectic Cl systems by molecular dynamics simulation, Appl. Sci. 8 (2018) 1874. 
  25. K. Igarashi, Y. Okamoto, J. Mochinaga, H. Ohno, X-Ray diffraction study of molten eutectic LiF-NaF-KF mixture, J. Chem. SOC., Faraday Trans. 84 (1988) 4407-4415.  https://doi.org/10.1039/f19888404407
  26. S.T. Lam, Q.-J. Li, J. Mailoa, C. Forsberg, R. Ballinger, J. Li, The Impact of Hydrogen Valence on its Bonding and Transport in Molten Fluoride Salts, in: Electronic Supplementary Material (ESI) for J Mater Chem A, The Royal Society of Chemistry, 2021. https://www.rsc.org/suppdata/d0/ta/d0ta10576g/d0ta10576g1.pdf. 
  27. B. Mignacca, G. Locatelli, Economics and finance of molten salt reactors, Prog. Nucl. Energy 129 (2020), 103503. 
  28. C. Andreades, R.O. Scarlat, L. Dempsey, P. Peterson, Reheat-air Brayton combined cycle power conversion design and performance under nominal ambient conditions, J. Eng. Gas Turbines Power 136 (2014), 062001. 
  29. C.W. Forsberg, Market basis for salt-cooled reactors: dispatchable heat, hydrogen, and electricity with assured peak power capacity, Nucl. Technol. 206 (2020) 1659-1685.  https://doi.org/10.1080/00295450.2020.1743628
  30. M.M. Tylka, J.L. Willit, J. Prakash, M.A. Williamson, Method development for quantitative analysis of actinides in molten salts, J. Electrochem. Soc. 162 (2015). H625-H633.  https://doi.org/10.1149/2.0401509jes
  31. S. Sharma, A.S. Ivanov, C.J. Margulis, A Brief guide to the structure of high-temperature molten salts and key aspects making them different from their low-temperature relatives, the ionic liquids, J. Phys. Chem. B 125 (2021) 6359-6372.  https://doi.org/10.1021/acs.jpcb.1c01065
  32. S.-C. Lee, Y. Zhai, Z. Li, N.P. Walter, M. Rose, B.J. Heuser, Comparative studies of the structural and transport properties of molten salt FLiNaK using the machine-learned neural network and reparametrized classical forcefields, J. Phys. Chem. B 125 (2021) 10562-10570.  https://doi.org/10.1021/acs.jpcb.1c05608
  33. A.E. Galashev, V.P. Skripov, Stability of Lennard-Jones crystal structures in the molecular dynamics model, J. Struct. Chem. 26 (1985) 716-721.  https://doi.org/10.1007/BF00773266
  34. A.E. Galashev, V.P. Skripov, Stability and structure of a two-component crystal using a molecular dynamics model, J. Struct. Chem. 27 (1986) 407-412. https://doi.org/10.1007/BF00751820