Electrochemical studies and analysis of 1–10wt% UCl3 concentrations in molten LiCl–KCl eutectic

Hoover, Robert O.; Shaltry, Michael R.; Martin, S.O.; Sridharan, Kumar; Phongikaroon, Supathorn

doi:10.1016/j.jnucmat.2014.05.057

Cited by 66 publications

(47 citation statements)

References 16 publications

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“…By comparing the properties of cerium with those of uranium, both are very stable in the trivalent form in LiCl-KCl salt and reduced to metal form by gaining three electrons at certain potentials. However, the standard reduction potential of UCl 3 is ranging from -2.4 to -2.6 V versus Cl 2 /Cl − reference electrode, [5][6][7][8][9] which is about 0.7 V more positive than the standard reduction potential for CeCl 3 . The diffusion coefficients for UCl 3 in LiCl-KCl molten salt have been reported by many researchers, [4][5][6][7][8][9]11 which are shown in the Figure 13.…”

Section: Electrochemical Impedance Spectroscopy (Eis)-mentioning

confidence: 82%

“…They performed CP and chronoamperometry (CA), and linear sweep voltammetry to determine the diffusion coefficients. Hoover et al in 2014 9 extended the uranium concentration in LiCl-KCl molten salt up to 10 wt% and observed the electrochemical and thermodynamic behaviors of uranium using CV, CP, and anodic stripping voltammetry. These data are valuable to a development of kinetic models, which can be useful for understanding the main features of actinide deposition at the electrode surface, and also for prediction of material distribution in an electrorefiner of a safeguarding aspect.…”

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confidence: 99%

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Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt

Yoon

Phongikaroon

2015

J. Electrochem. Soc.

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Thermodynamic and electrochemical properties of cerium in LiCl-KCl eutectic salt have been measured and studied at different concentrations (0.5 -4 wt%) and temperatures (698 K -798 K) via both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques as a part of developing a fundamental understanding and methodology in materials detection and accountability for pyroprocessing technology. CV experiments were performed to determine the diffusion coefficient and apparent standard potential of CeCl 3 on the tungsten working electrode. The diffusion coefficient was calculated by using Delahay equation, and raging from 0.48 × 10 −5 to 1.01 × 10 −5 cm 2 s −1 . Results reveal that the calculated diffusion coefficient of CeCl 3 in the salt follows the Arrhenius temperature relationship and it is weakly affected by the changes in concentration of CeCl 3 . The apparent standard potentials were calculated from peak potentials showing linear relationship with temperature. Exchange current density values of Ce 3+ /Ce couple in the salt were obtained from EIS experiments, ranging from 0. Pyroprocessing technology has been proposed as another promising method for the recovery and recycle of uranium and actinide elements from the used nuclear fuel. An essential step in this technology is the electrorefining process in which uranium is selectively recovered by using solid cathodes in chloride-based molten salt at high temperature.1 Then, co-recovery of uranium and transuranic elements can be accomplished by replacing the solid cathodes with a liquid cadmium cathode because the reduction potentials of the elements become close when the liquid cadmium is used as a cathode electrode.2,3 Since uranium is the major element in most nuclear fuel cycle paths as well as pyroprocessing technology, the assessment of accurate thermochemical data for the element in the molten salt is extremely important. 4Many studies on the thermochemical properties of uranium have been done in LiCl-KCl molten eutectic salt in different temperature ranges. Masset et al. 5,6 investigated diffusion coefficients of actinides and lanthanides in LiCl-KCl via cyclic voltammetry (CV) and chronopotentiometry (CP). Kuznetsov et al. 7,8 studied the electrochemical behaviors of actinides and rare-earth metals in LiCl-KCl salt. They performed CP and chronoamperometry (CA), and linear sweep voltammetry to determine the diffusion coefficients. Hoover et al. in 2014 9 extended the uranium concentration in LiCl-KCl molten salt up to 10 wt% and observed the electrochemical and thermodynamic behaviors of uranium using CV, CP, and anodic stripping voltammetry. These data are valuable to a development of kinetic models, which can be useful for understanding the main features of actinide deposition at the electrode surface, and also for prediction of material distribution in an electrorefiner of a safeguarding aspect. Zhang 10 developed a kinetic model for electrorefining system showing that the model is capable of predicting the kinetic features and...

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Section: Electrochemical Impedance Spectroscopy (Eis)-mentioning

confidence: 82%

mentioning

confidence: 99%

Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt

Yoon

Phongikaroon

2015

J. Electrochem. Soc.

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“…Molten salt electrolytes have been proven to be a suitable media for the electrochemical separation of actinides; many studies have http shown the ability to anodically titrate nuclear species into molten salts [4][5][6][7][8][9], to electroreduce/electrodeposit nuclear species from molten salts [5,[10][11][12][13][14][15] and the ability to scale-up molten salt separation processes to the kg scale [16][17][18]. Inman et al showed the electrochemical reversibility of U 3+ |U system in LKE [5] and Sakamura et al have shown the 4-electron transfer electroreduction process of UO 2 to U in CaCl 2 and LiCl salts [19].…”

Section: Introductionmentioning

confidence: 99%

Following the electroreduction of uranium dioxide to uranium in LiCl–KCl eutectic in situ using synchrotron radiation

Brown

Abdulaziz

Jervis

et al. 2015

Journal of Nuclear Materials

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“…Electroanalytical techniques using cyclic voltammograms (CVs) are a promising approach that has been developed to provide these measurements. [1][2][3][4] Earlier voltammetry studies showed that CVs were able to provide very accurate results at low concentrations (0-2 wt%) for molten chloride salts containing U and Pu;…”

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confidence: 99%

Communication—Quantitative Voltammetric Analysis of High Concentration Actinides in Molten Salts

Hoyt

Willit

Williamson

2017

J. Electrochem. Soc.

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Previous electroanalytical studies have shown that cyclic voltammetry can provide accurate quantitative measurements of actinide concentrations at low weight loadings in molten salts. However, above 2 wt%, the techniques were found to underpredict the concentrations of the reactant species. This work will demonstrate that much of the discrepancy is caused by uncompensated resistance and cylindrical diffusion. An improved electroanalytical approach has therefore been developed using the results of digital simulations to take these effects into account. This approach allows for accurate electroanalytical predictions across the full range of weight loadings expected to be encountered in operational nuclear fuel processing equipment. Accurate measurement of actinide concentrations is critical for the control and accountancy of nuclear materials within molten salts used in nuclear fuel processing. Electroanalytical techniques using cyclic voltammograms (CVs) are a promising approach that has been developed to provide these measurements. [1][2][3][4] Earlier voltammetry studies showed that CVs were able to provide very accurate results at low concentrations (0-2 wt%) for molten chloride salts containing U and Pu; 2 however, at high concentrations (>2 wt%) the electroanalytical measurements were found to deviate considerably from inductively coupled plasma/atomic emission spectroscopy (ICP/AES) results. The possibility of reduced diffusion coefficients at high concentrations (leading to concomitant reduction in peak currents) was mentioned as one source of the discrepancy.3 However, other effects can lead to similar attenuation. For example, uncompensated resistance, R u , has long been known to alter the current response in CVs, and the effects thereof must be addressed even in high conductivity molten salts. As cylindrical rods are commonly used as electrodes in molten salts, the effects from cylindrical diffusion must too be addressed.Many classic papers exist on the subject of uncompensated resistance, both for soluble-soluble and soluble-insoluble reactions. [5][6][7] Cylindrical diffusion has too been examined in several classic papers. [8][9][10] Specific to molten salts, a number of recent electroanalytical papers have included iR-correction to partially account for the effects of uncompensated resistance, 4,11 but simple ex post facto correction of the applied potential does not account for the alteration to the evolution of the current response and is hence inadequate. Positive feedback iR-compensation is an experimental approach to address the effect of uncompensated resistance, 12 but oscillations and feedback issues that occur above ∼90% R u make the approach suboptimal for electroanalytical measurements.13 Thus, while the existence of both uncompensated resistance and cylindrical diffusion effects is well known, the combined examination of the resulting electroanalytical implications for a soluble-insoluble reaction has not been performed.Therefore, in this work, digital simulations of CVs with combined u...

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Electrochemical studies and analysis of 1–10wt% UCl3 concentrations in molten LiCl–KCl eutectic

Cited by 66 publications

References 16 publications

Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt

Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt

Following the electroreduction of uranium dioxide to uranium in LiCl–KCl eutectic in situ using synchrotron radiation

Communication—Quantitative Voltammetric Analysis of High Concentration Actinides in Molten Salts

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Electrochemical studies and analysis of 1–10wt% UCl3 concentrations in molten LiCl–KCl eutectic

Cited by 66 publications

References 16 publications

Electrochemical Properties and Analyses of CeCl3in LiCl-KCl Eutectic Salt

Electrochemical Properties and Analyses of CeCl3in LiCl-KCl Eutectic Salt

Following the electroreduction of uranium dioxide to uranium in LiCl–KCl eutectic in situ using synchrotron radiation

Communication—Quantitative Voltammetric Analysis of High Concentration Actinides in Molten Salts

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Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt

Electrochemical Properties and Analyses of CeCl₃in LiCl-KCl Eutectic Salt