Study of entrainment of Li2O in product from direct electrolytic reduction of UO2 in molten LiCl–Li2O. Part 1: Post-processing and analysis techniques

• Published in: Journal of nuclear materials Vol. 529; no. C; p. 151913
• Main Authors: Burak, Adam, Chamberlain, Jarom, Simpson, M.F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2020; Elsevier BV; Elsevier
• Subjects: Entrainment; Error analysis; Lithium chloride; Lithium oxides; Oxygen; Oxygen content; Post-processing; Reduction; Reduction (electrolytic); Scale (corrosion); Thermogravimetric analysis; Thermogravimetry; Titration; Uranium; Uranium dioxide; Uranium oxide; Uranium oxides
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2019.151913

This paper describes experimental and characterization methods for gram-scale uranium oxide electrolytic reduction tests in molten LiCl–Li2O. Post-test analysis of the cathodically reduced UO2 involves acid-base titration and thermogravimetric analysis under flowing air. The titration was used to measure Li2O entrained inside reduced UO2 particles. Centrifugal salt removal was demonstrated to eliminate Li2O from the basket, but the Li2O entrained in the reduced uranium particles remained and was reacted over a period of several days in an autotitrator. Measuring the mass increase by thermogravimetry while heating to 800 °C and flowing air was found to be an effective way to measure the reduction extent, which was verified with pure U metal. The error of this measurement was estimated to be 1.65%. In addition, a LECO oxygen compositional analyzer was used to independently verify the oxygen content in the product from the thermogravimetric analysis. •Experimental and characterization methods for gram-scale uranium oxide reduction tests in molten LiCl–Li2O were developed.•A post-reduction sampling procedure was developed to analyze reduced U cathodes for Li2O entrainment and reduction extent.•A centrifugal salt removal technique was developed to simplify titration (entrainment) analysis.•TGA and LECO analyses were compared as candidates for reduction extent measurement.