Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8066837 | Annals of Nuclear Energy | 2018 | 7 Pages |
Abstract
Cyclic voltammetry (CV) analysis was performed to determine the behavior of Dysprosium (Dy) and Lanthanum (La) in molten FLiNaK salt (LiF-NaF-KF: 46.5-11.5-42â¯mol%) and to understand the mechanism driving the electrochemical reactions. The goals of these experiments are to understand the behavior of contaminants and nuclear fission products related to the Fluoride Salt-cooled High-Temperature Reactor (FHR) concept, and to generate a reliable source of electrochemical properties in fluoride salts. The tests were performed at 600-650-700â¯Â°C for Dy and 650-700-750â¯Â°C for La in a glassy carbon crucible contained within an inert argon atmosphere. A platinum wire quasi-reference electrode exhibited stable potential throughout experiments and allowed for thermodynamic reference between test species and known redox couple (F2/Fâ). The electrochemical reduction of Dy and La (assumed three-electron, single-step transfer) maintained quasi-reversibility at the solid tungsten electrode for scan rates of 160â¯mV/s and below during CV. For scan rates of 200â¯mV/s and above, significant deviation from reversibility was evidenced by increasing separation between anodic and cathodic peaks. For Dy3+, the diffusion coefficient was calculated as D [cm2/s]â¯=â¯0.0538âexp(â6193/T(K)) and the activation energy Eaâ¯=â¯51.5â¯kJ/mol. The diffusion coefficient of La3+ was calculated as D [cm2/s]â¯=â¯14.252âexp(â15285/T(K)) and the activation energy Eaâ¯=â¯127â¯kJ/mol. The apparent potential of the La3+/La0 redox reaction was determined as E0â[V vs. K+/K]â¯=â¯â0.368â¯+â¯0.001119âT[K] and for the Dy3+/Dy0 reaction as E0â[V vs. K+/K]â¯=â¯0.0626â¯+â¯0.00088âT[K].
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Authors
Ryan Chesser, Shaoqiang Guo, Jinsuo Zhang,