Investigation of a U(IV)/U(III) Thermodynamic Reference Electrode for High-Temperature Molten Fluoride Salts

Gunnell, Ethan; Blackwood, Brittney L.; Wilson, Caden; Harb, John N.; Memmott, Matthew J.

doi:10.1149/1945-7111/ada588

Investigation of a U(IV)/U(III) Thermodynamic Reference Electrode for High-Temperature Molten Fluoride Salts

Journal Article · Mon Jan 13 00:00:00 EST 2025 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1945-7111/ada588· OSTI ID:2496625

^[1]; Blackwood, Brittney L. ^[1]; Wilson, Caden ^[1]; ^[2]; Memmott, Matthew J. ^[2]

AlphaTech Research Corp., American Fork, UT (United States)
AlphaTech Research Corp., American Fork, UT (United States); Brigham Young University, Provo, UT (United States)

While thermodynamic reference electrodes with known and stable potentials are common in traditional aqueous systems, the high temperature and corrosive environment of a molten fluoride salt makes achieving long term stability with a thermodynamic reference electrode challenging, especially at temperatures of 600°C or higher. In this work, a thermodynamic reference electrode consisting of U(IV)/U(III) in a boron nitride compartment was evaluated for use in FLiBe at temperatures ≥ 600°C. FLiBe used in the study was purified by AlphaTech's proprietary process and characterized by ICP-MS and square wave voltammetry. The free oxide concentration was <2 ppm. Using the purified FLiBe, the U(IV)/U(III) thermodynamic reference electrode was shown to provide a stable, well-defined, and reproducible potential for more than 600+ hours of use in different tests. Moreover, the thermodynamic reference electrode showed a consistent potential with no signs of failure, even after being cooled between tests and then reheated for reuse. Thus, the U(IV)/U(III) reference electrode is suitable for use in rigorous electrochemical studies in molten fluoride salts. As a result, it may be useful as a common standard, facilitating the advancement of nuclear applications such as isotope separation or online monitoring of reactor systems through improved certainty in the measurement of thermodynamic potentials.

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This content will become publicly available on Tue Jan 13 00:00:00 EST 2026

Research Organization:: AlphaTech Research Corp., American Fork, UT (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Office of SBIR/STTR Programs (SBIR/STTR)

Grant/Contract Number:: SC0022922

OSTI ID:: 2496625

Journal Information:: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society; ISSN 0013-4651

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

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