Redox potentials of the 0.73LiF–0.27BeF 2  system uranium tri- and tetrafluorides

Stepan P. Arkhipov; Yury P. Zaikov; Pavel A. Arkhipov; Albert R. Mullabaev

doi:10.15826/elmattech.2026.5.079

Redox potentials of the 0.73LiF–0.27BeF₂ system uranium tri- and tetrafluorides

Stepan P. Arkhipov, Yury P. Zaikov, Pavel A. Arkhipov, Albert R. Mullabaev

Abstract

The emf method was implied to measure the redox potentials of the molten LiF–BeF₂–UF₄/UF₃ mixture at the temperatures of 923, 973 and 1023 K with a different ratio of uranium trifluoride and uranium tetrafluoride in the melt. Dependencies of the redox potentials of the studied systems have been obtained using a molybdenum indicator electrode. The redox potentials were found to change linearly as the temperature increased within the whole studied temperature range. Comparative analysis of the experimentally obtained data elucidated that measured redox potentials in the 0.73LiF–0.27BeF₂ melts correspond to the definite UF₄/UF₃ ratio. The value of the media redox potential may be used to evaluate the molar fraction concentrations of trivalent and tetravalent uranium in the melt.

Keywords

redox potential; uranium ions; fluoride melt; lithium fluoride; beryllium fluoride

Full Text:

PDF

References

Status and Trends in Spent Fuel and Radioactive Waste Management: IAEA Nuclear Energy Series No NW-T-1.14. Vienna: 2018. https://dx.doi.org/10.61092/iaea.bxkd-wzfk

Energeticheskiye rynki v period globalnykh peremen (Energy markets during global changes). Ed. Togaova NV, Kvashnina YuD. Moscow: IMEMO RAS; 2015. 131 p. Russian

Locatelli G, Mancini M, Todeschini N, Generation IV nuclear reactors: Current status and future prospects, Energy Policy, 61 (2013) 1503–1520. https://dx.doi.org/10.1016/j.enpol.2013.06.101

Kelly JE, Generation IV International Forum: A decade of progress through international cooperation, Prog. Nucl. Energy, 77 (2014) 240–246. https://dx.doi.org/10.1016/j.pnucene.2014.02.010

Pioro IL, Rodriguez GH, Generation IV International Forum (GIF), Handb. Gener. Iv Nucl. React., (2023) 111–132. https://dx.doi.org/10.1016/b978-0-12-820588-4.00010-4

Bourg S, Lee Y and Křepel J, Generation IV international forum, Glob. Prog. Molten Salt React., (2024) 201–212. https://dx.doi.org/10.1016/b978-0-323-99377-7.00022-4

Zaikov YuP, Khokhlov VA, Afonichkin VK, Volkov SV, Omelchuk AA. Some problems of new generation molten salt reactor chemistry. In: XVI Russian Conference on Physical Chemistry and Electrochemistry of Molten and Solid Electrolytes; 2013 Sep 16–20; Ekaterinburg, Russia. pp. 87–88.

Ponomarev LI, Belonogov MN, Volkov IA, Simonenko VA, Sheremet’eva UF, Np, Am, Cm transmutation in different types of reactors, At. Energy, 126 (2019) 132–137. https://doi.org/10.1007/s10512-019-00529-x

Bahri CN, Al-Areqi WM, Ruf M, Majid AA, Characteristic of molten fluoride salt system LiF-BeF2 (Flibe) and LiF-NaF-KF (Flinak) as coolant and fuel carrier in molten salt reactor (MSR), AIP Conf. Proc., 1799 (2017) 040008. https://dx.doi.org/10.1063/1.4972932

Ignat’ev VV, Subbotin SA, Feinberg OS, Accident resistance of molten-salt nuclear reactor, At. Energy, 124 (2018) 371–378. https://dx.doi.org/10.1007/s10512-018-0425-2

Lizin AA, Ponomarev LI, Tomilin SV, Carrier salt selection for molten salt reactor with fast neutron spectrum, Voprosy atomnoy nauli y tekhniki, Seriya: Materialovedeniye y noviye materialy, 3 (2016) 80–89.

Tkacheva OYu, Rudenko AV, Kataev AA, Mushnikov PN, et al., The viscosity of molten salts based on the LiF–BeF2 system, Russ. J. Non-ferrous Met., 63 (2022) 276–283. https://dx.doi.org/10.3103/s1067821222030117

Redkin A, Khudorozhkova A, Il'Ina E, Pershina S, et al., Density and heat capacity of some molten mixtures in system LiF-BeF2-UF4, J. Mol. Liq., 341 (2021) 117215. https://dx.doi.org/10.1016/j.molliq.2021.117215

Bobrova KO, Dokutovich VN, Mushnikov PN, Thermophysical properties of several molten mixtures of the LiF–BeF2–UF4 system, Russ. Met. (metally), 2023 (2023) 126–135. https://dx.doi.org/10.1134/s0036029523020039

Ignatiev VV, Abalin SS, Gurov MY, Zakirov RY, et al., Reactor with circulating fuel based on molten metal fluorides for Np, Am, Cm incineration, At. Energy, 129 (2021) 122–126. https://dx.doi.org/10.1007/s10512-021-00722-x

Jiang S, Lan J, Wang L, Liu Y, et al., Competitive coordination of chloride and fluoride anions towards trivalent lanthanide cations (La3+ and Nd3+) in molten salts, Chem. – Eur. J., 27(45) (2021) 11721–11729. https://dx.doi.org/10.1002/chem.202101505

Leblanc D, Molten salt reactors: A new beginning for an old idea, Nucl. Eng. Des., 240(6) (2010) 1644–1656. https://dx.doi.org/10.1016/j.nucengdes.2009.12.033

Holdsworth AF, Eccles H, Sharrad CA, George K, Spent nuclear fuel—Waste or resource? The potential of strategic materials recovery during recycle for sustainability and advanced waste management, Waste, 1(1) (2023) 249–263. https://dx.doi.org/10.3390/waste1010016

Haynes AMD, Chen D, Pyroprocessing as a solution for green, Sovereign energy in Southeast Asia, J.N.M.M., 50(4) (2023) 5–15(11).

Ponomarev LI, Seregin MB, Parshin AP, Mel’nikov SA, et al., Fuel salt for the molten-salt reactor, At. Energy, 115 (2013) 6–11. https://doi.org/10.1007/s10512-013-9739-2

Nikitina EV, Karfidov EA, Zaikov YuP, Corrosion of advanced metal materials in fluoride melts for liquid salt reactors, The Melts, 1 (2021) 21–45. Russian. https://doi.org/10.31857/S0235010621010072

Surenkov AI, Ignat’Ev VV, Abalin SS, Konakov SA, Uglov VS, Corrosion resistance and mechanical stability of nickel alloys in molten-salt nuclear reactors, At. Energy, 124 (2018) 43–49. https://dx.doi.org/10.1007/s10512-018-0372-y

McCoy HE. The INOR-8 story. Oak Ridge National Lab.: Tennessee, US; 1969. 179 p. https://dx.doi.org/10.2172/4072851

Thoma RE. Chemical aspects of MSRE operations. Oak Ridge National Lab.: Tennessee, US; 1971. 145 p. https://dx.doi.org/10.2172/12536581

Rosenthal MW. Molten-salt Reactor Program Semiannual Progress Report: For Period Ending August 31, 1968. Oak Ridge National Lab.: Tennessee, US; 1969. 170 p.

Guo S, Shay N, Wang Y, Zhou W, Zhang J, Measurement of europium (III)/europium (II) couple in fluoride molten salt for redox control in a molten salt reactor concept, J. Nucl. Mater., 496 (2017) 197–206. https://dx.doi.org/10.1016/j.jnucmat.2017.09.027

Sankar KM, Keiser JR, Sulejmanovic D, Lowe TM, Singh PM, Evaluation of corrosion behavior of various Fe- and Ni-based alloys in molten Li2–BeF4 (FLiBe), Nucl. Technol., 210(3) (2024) 391–408. https://dx.doi.org/10.1080/00295450.2023.2229176

Laurenty B, Peterson PF. The LM-LS experiment: investigating corrosion control in liquid fluoride salts by liquid alkali metal [Master's dissertation]. Berkeley, CA (USA): University of California; 2006. 91 p.

Carotti F. Electrochemical Studies for Tritium Transport in Graphite and Molten Flibe [dissertation]. Madison, WI (US): The University of Wisconsin-Madison; 2019. 233 p.

Janz GJ, Tomkins RPT, Corrosion in molten salts: an annotated bibliography, Corrosion, 35(11) (1979) 485–504. https://dx.doi.org/10.5006/0010-9312-35.11.485

Littlewood R, Argent E, Electrochemical studies of the behaviour of metals in fused chlorides, Electrochimica Acta, 4(2–4) (1961) 155–169. https://dx.doi.org/10.1016/0013-4686(61)80014-5

Ignat’ev V, Surenkov A, Voltammetric measurements on the [U(IV)]/[U(III)] couple and embrittlement of high nickel alloys in fuel LiF-BeF2-UF4 salt with tellurium addition in application to molten salt reactor, Corros. Sci., 160 (2019) 108164. https://dx.doi.org/10.1016/j.corsci.2019.108164

Arkhipov SP, Zaikov YuP, Arkhipov PA, Mullabaev AR, Interaction between uranium trifluoride and the mixture of lithium and beryllium fluorides, J. Electrochem. Soc., 171(6) (2024) 062504. https://dx.doi.org/10.1149/1945-7111/ad4f1f

Zaikov YuP, Arkhipov PA, Arkhipov SP, Isakov AV, Mushnikov PN, Mullabaev AR, authors; JSC «Science and Innovations», assignee. Nickelevy electrod sravneniya dly electrokhimicheskikh issledovaniy svoistv rasplavov na osnove LiF-BeF2. Russian Federation patent RU No 2843814. 2025 Mar 05. Russian.

Baes Jr CF. The Chemistry and Thermodynamics of Molten-Salt-Reactor Fluoride Solutions. USA; 1965. 36 p. https://dx.doi.org/10.2172/4576123

Smirnov MV. Elektrodniye potencialy v rasplavlennykh sredakh [Electrode potentials in chloride melts]. Moscow: Nauka; 1973. 247 p. Russian

Hoover RO, Shaltry MR, Martin S, Sridharan K, Phongikaroon S, Electrochemical studies and analysis of 1–10 wt. % UCl3 concentrations in molten LiCl–KCl eutectic, J. Nucl. Mater., 452(1–3) (2014) 389–396. https://dx.doi.org/10.1016/j.jnucmat.2014.05.057

Masset P, Konings RJ, Malmbeck R, Serp J, Glatz J, Thermochemical properties of lanthanides (Ln = La, Nd) and actinides (An = U, Np, Pu, Am) in the molten LiCl–KCl eutectic, J. Nucl. Mater., 344(1–3) (2005) 173–179. https://dx.doi.org/10.1016/j.jnucmat.2005.04.038

Geran S, Chamelot P, Serp J, Gibilaro M, Massot L, Electrochemistry of uranium in molten LiCl–LiF, Electrochimica Acta, 355 (2020) 136784. https://dx.doi.org/10.1016/j.electacta.2020.136784

DOI: https://doi.org/10.15826/elmattech.2026.5.079

Copyright (c) 2026 Stepan P. Arkhipov, Yury P. Zaikov, Pavel A. Arkhipov, Albert R. Mullabaev