Electrochemical behavior of actinide ions in LiCl–KCl eutectic melts

The electrochemical properties of the chlorides of the actinides U, Pu, Np and Am (AnCl 3 ) were investigated by transient electrochemical techniques in the LiCl-KCl eutectic at 400 -550 • C. The diffusion coefficients of the cations and the apparent standard potentials of the redox systems on an inert W electrode were measured. The Gibbs energy of dilute solutions of AnCl 3 as well as the activity coefficients were derived from electrochemical measurements. In addition, the electrochemical behaviour of the actinides on an Al electrode was investigated. They formed AnAl 4 alloys, the formation potentials of which allowed a quantitative recovery of the actinides and their separation from fission products and especially from lanthanides. In addition, the thermochemical properties of the AnAl 4 alloys were determined by electrochemical measurements.

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“…Chemicals and electrode preparation have already been reported [11]. Only the preparation of the actinide solutions is described in this paper.…”

Section: Chemicalsmentioning

confidence: 99%

Assessment of the Thermochemical Properties of Actinides in Molten Chlorides

Masset

Apostolidis

Malmbeck

et al. 2008

Zeitschrift Für Naturforschung A

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“…Serrano et al reported that this couple was derived from uranium sub-halide complex species 18 while Shirai et al regarded it as underpotential deposition (UPD). 19 However, because it is well known that the UPD reaction does not occur on a carbon surface, 20 the peaks A2/C2 observed on the graphene surface are likely attributable to the sub-halide complex rather than the UPD reaction.…”

Section: Resultsmentioning

confidence: 99%

“…21,22 There is a redox couple (A3/C3) near ¹0.25 V that is attributed to U 3+/4+ redox reactions. 19,21,23 For comparison, the CV was obtained using the GC electrode [ Fig. 3(b)] under nearly the same condition that was applied for the graphene electrode [ Fig.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reactions of Uranium Trichloride on a Graphene Surface in LiCl-KCl Molten Salt

et al. 2014

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The electrochemcal reactions of uranium trichloride on the surfaces of dimensionally very dissimilar carbon-based materials such as glassy carbon (GC) and graphene in LiCl-KCl eutectic melt were investigated using cyclic voltammetry (CV) and scanning electron microscopy (SEM). The cathodic scanning of CV displayed that the Li intercalation reaction into the GC electrode governs at the potential of approximately −1.45 V vs. Ag|Ag + where the electrodeposition reaction of uranium may occur. On the other hand, the graphene electrode presented electrodeposition current of the uranium without interference at −1.45 V vs. Ag|Ag + because the Li intercalation reaction was extensively diminished on the very thin graphene film. In addition, it was successful to measure the electrodeposition current of gadolinium at more positive than −2.1 V without the interference of the Li intercalation into the graphene substrate. Consequently, the significant reduction of the Li intercalation reaction on the nanometer thick carbon electrode extensively expands the electrochemical potential window of the carbon-based electrode with respect to the bulk carbon electrode in LiCl-KCl melt, emphasizing that the graphene has a great potential as a cathode electrode in high temperature molten salt electrolytes.

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“…Plutonium trichloride was prepared by the chlorination of PuPt3 with CdCl2 (> 99.99%; Anderson Physics Laboratory) in LiCl-KCl/Cd system at 773 K, which produced light green salts containing about 20 wt% PuCl3. 12 PuPt3 was synthesized by heating the mixture of PuN prepared by carbothermic reduction of PuO2 and Pt powders (>99.95%; Rare Metallic Co., Ltd.) in an Ar gas (>99.999%) stream at 1073 K. 13 The salt obtained in the above-mentioned procedure was diluted by the addition of the LiCl-KCl eutectic melt in order to obtain the adequate concentration of PuCl3 for the electrochemical measurements. The concentration of PuCl3 in the LiCl-KCl eutectic melts was determined by ICP-AES.…”

Section: Methodsmentioning

confidence: 99%

Electrode Reaction of Pu3+/Pu Couple in LiCl-KCl Eutectic Melts: Comparison of the Electrode Reaction at the Surface of Liquid Bi with That at a Solid Mo Electrode

et al. 2001

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Pyrochemical reprocessing of nuclear fuels using molten salt as a solvent shows promise for advanced nuclear engineering because of its compactness, economy, radiation resistance and nonproliferation. 1 In the electrorefining process, which is a key step in pyrochemical reprocessing, spent fuels are anodically dissolved in LiCl-KCl eutectic melt, and U, Pu and minor actinides (MAs; Np, Am, Cm, etc.) are recovered together at the cathode. 2,3 It has been proposed that U could be selectively recovered at the solid cathode due to the difference in the formation energies of chlorides, and Pu and MAs at the liquid metal cathode due to their small activity coefficients in the liquid metals such as Cd or Bi. 4,5 During the dissolution of spent fuel, metals or nitrides of alkali, alkaline earths and rare earths are also dissolved into the salt phase at the same time, while metal fission products such as Ru, Tc and Mo are not dissolved. In order to recover actinides effectively from the salt phase, electrolysis using a liquid metal cathode or extraction separation between the salt and the liquid metal has been proposed.2,3 Therefore, several studies were conducted on the distribution behaviors of actinides, alkali, alkaline earths and rare earths between LiCl-KCl eutectic melt and liquid metal, and the activities and separation factors of these elements in liquid metal phase were estimated. [4][5][6][7][8] From the standpoint of separation of actinides and rare earths, Bi is more convenient than Cd as the liquid metal. 4 However, there is little information on the electrode reaction of Pu and MAs at the liquid Bi electrode, and the mechanism has not been completely elucidated. For the liquid Cd electrode, the deviation of the redox potential of metal deposition was interpreted in terms of a lowering of activity of the deposited metal in the Cd phase, and the relation between the activity and the formation energy of intermetallic compounds such as PuCd6 was evaluated in the previous work. 9 The change of the redox potential on metal deposition at Hg electrode or amalgam electrode in aqueous solution has been interpreted in terms of a lowering of activity of the deposited metal in the Hg or amalgam phase. 10,11 The relation between the activity and the formation energy of intermetallic compounds between Hg and deposited metal, however, has not been analyzed in detail.In the present paper, the electrode reaction of Pu 3+ /Pu couple at the interface between LiCl-KCl eutectic melt and liquid Bi was investigated in comparison with a solid electrode. The difference between the redox potentials of Pu 3+ /Pu at the solid electrode and at liquid Bi electrode was thermodynamically interpreted based on the formation energy of PuBi2. The Gibbs free energies of formation of the intermetallic compound, PuBi2, were evaluated by the analysis of cyclic voltammograms in the temperature range from 723 to 823 K. ExperimentalThe electrochemical cell used for the voltammetric studies is shown in Fig. 1. A liquid Bi electrode, which was used a...

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Electrochemical behavior of actinide ions in LiCl–KCl eutectic melts

Cited by 95 publications

References 13 publications

Assessment of the Thermochemical Properties of Actinides in Molten Chlorides

Assessment of the Thermochemical Properties of Actinides in Molten Chlorides

Electrochemical Reactions of Uranium Trichloride on a Graphene Surface in LiCl-KCl Molten Salt

Electrode Reaction of Pu3+/Pu Couple in LiCl-KCl Eutectic Melts: Comparison of the Electrode Reaction at the Surface of Liquid Bi with That at a Solid Mo Electrode

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