Actinides recovery from molten salt/liquid metal system by electrochemical methods

Iizuka, Masatoshi; Koyama, Tadafumi; Kondo, Naruhito; Fujita, Reiko; Tanaka, Hiroshi

doi:10.1016/s0022-3115(97)00096-2

Cited by 63 publications

(44 citation statements)

References 3 publications

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“…3), and the absence of the other expected signals might be caused by the relatively slower formation kinetics of these intermetallic compounds. Specifically, different from LnM 11 (M = Bi or Cd) inter- metallic compounds, 19,20,24 the formation potential of intermetallic compound CeZn 11 (plateau 11) is close to that of pure Zn metal, which suggests that intermetallic compound CeZn 11 should be more thermodynamically stable than intermetallic compound CeCd 11 .…”

Section: Resultsmentioning

confidence: 92%

“…During this process, potential plateaus corresponding to the two intermetallic phases coexisting at the Zn-coated electrode would be observed. 11 , respectively. However, only six signals corresponding to these plateaus can be observed in CVs (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…6a, the presence of both Zn and CeZn 11 phases is identified. It reveals that the deposited Ce exists in the form of the most thermodynamically stable intermetallic compound CeZn 11 42 at the liquid Zn electrode. Fig.…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical Extraction of Cerium by Forming Ce-Zn Alloys in LiCl-KCl Eutectic on W and Liquid Zn Electrodes

Wang

Liu

Tang

et al. 2015

J. Electrochem. Soc.

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The electrochemical formation of Ce-Zn alloys in LiCl-KCl eutectic was systematically investigated by cyclic voltammetry (CV), square wave voltammetry (SWV) and open circuit chronopotentiometry (OCP). Due to the decrease of Ce activity in the metal phase of formed Ce-Zn alloys, the deposition potential of Ce(III) at a liquid Zn electrode was found to be 0.64 V more positive than that on an inert W electrode. The co-reduction behaviors of Ce(III) and Zn(II) ions were also studied in LiCl-KCl eutectic. Signals associated with six and nine Ce x Zn y intermetallic compounds were detected by CV and OCP techniques, respectively. In addition, potentiostatic electrolyses were carried out to extract Ce at a liquid Zn electrode in LiCl-KCl-CeCl 3 melt and on a W electrode in LiCl-KCl-CeCl 3 -ZnCl 2 melt, respectively. Deposited samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that intermetallic compound CeZn 11 was prepared on both the inert W electrode and liquid Zn electrode. Pyrochemical reprocessing of spent nuclear fuels is now considered to be one of the most promising options in nuclear fuel cycles due to their outstanding properties such as high thermal and radiation stability which allows a shorter cooling time of fuels before reprocessing, compactness, high actinide content and inherent proliferation resistance.1-4 The aim of the traditional pyrochemical processing technology is to achieve a group-selective separation of all actinides (Ans) for recycling or transmutation, generating the minimum of ultimate waste flows with an acceptable decontamination of fission products. A typical process in pyrochemical reprocessing is the electrorefining, [5][6][7][8][9][10] in which lanthanides (Lns) and Ans in spent fuels are dissolved into molten chloride salt by anodic dissolution. Subsequently, Ans (e.g. U) are selectively deposited on the stainless steel cathode or liquid cadmium cathode with respect to their different redox potentials in melt. In contrast, most fission products (FPs) still remain in the electrolyte.8 Actually, Lns are the major and most awkward FPs and are difficult to be separated from Ans due to their similar chemical properties. On the other hand, Lns are well known to possess large neutron capture cross sections, which can spoil the neutron economy of reactor cores in the transmutation operation. Therefore, though quite challenging, it is still imperative to efficiently separate Ans from Lns.In recent years, liquid-liquid reductive extraction has attracted considerable interest as a promising technique for the separation of minor actinides (MAs) from Lns.11-15 During a typical separation process, the solute cations in molten salt are recovered into the liquid metal phase via direct electrolysis or reductive extraction, due to the low activity coefficients of their corresponding metal phases in liquid metals. Since the operation of liquid metals plays an important role in the pyrochem...

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 97%

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Electrochemical Extraction of Cerium by Forming Ce-Zn Alloys in LiCl-KCl Eutectic on W and Liquid Zn Electrodes

Wang

Liu

Tang

et al. 2015

J. Electrochem. Soc.

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“…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.…”

mentioning

confidence: 99%

“…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.…”

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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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Quantitative Analysis of Lanthanides in Molten Chloride by Absorption Spectrophotometry

Uda

Fujii

Fukasawa

et al. 2014

Molten Salts Chemistry and Technology

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Actinides recovery from molten salt/liquid metal system by electrochemical methods

Cited by 63 publications

References 3 publications

Electrochemical Extraction of Cerium by Forming Ce-Zn Alloys in LiCl-KCl Eutectic on W and Liquid Zn Electrodes

Electrochemical Extraction of Cerium by Forming Ce-Zn Alloys in LiCl-KCl Eutectic on W and Liquid Zn Electrodes

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

Quantitative Analysis of Lanthanides in Molten Chloride by Absorption Spectrophotometry

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