Electrolytic reduction behavior of U3O8 in a molten LiCl–Li2O salt

Park, B.H.; Lee, I.W.; Seo, Changwon

doi:10.1016/j.ces.2008.04.021

Cited by 33 publications

(14 citation statements)

References 23 publications

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“…13 The process finds application as an intermediate step to connect the oxide fuel cycle to metal fuel cycle, in which the spent nuclear oxide fuels are first electro-deoxidised to a metal alloy followed by its electrorefining and subsequent conversion to a metallic fuel. [14][15][16][17][18][19][20] Molten salt electrochemical reduction of U 3 O 8 [21][22][23][24][25][26][27] and UO 2 [28][29][30][31][32][33][34][35][36][37][38] to U was reported in this context by Korea Atomic Energy Research Institute (KAERI), Republic of Korea; Argonne National Laboratory (ANL), USA; Central Research Institute of Electric Power Industry (CRIEPI), Japan and Indira Gandhi Center for Atomic Research (IGCAR), India. LiCl melt containing small amounts of Li 2 O was used as the electrolyte and platinum as the anode in most of these studies, which were carried out at 923 K.…”

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confidence: 99%

Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt

Vishnu¹,

Sanil²,

Panneerselvam³

et al. 2013

J. Electrochem. Soc.

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Electrochemical reduction of high dense UO2 pellets (95% TD) was carried out in molten CaCl2-48mol% NaCl at 923 K by constant voltage and constant current modes of electrolysis using graphite as the anode with an aim to check the feasibility of reduction and to determine the reduction mechanism. Electro-reduction experiments were carried out at 3.3 V for different durations of time (6, 12, 19, 25, 35 and 44 h) in order to obtain partially reduced samples. The UO2 pellets electrolysed for 35 h and above were fully reduced whereas those samples electrolysed for lower durations of time showed only surface reduction. Low current galvanostatic electrolysis of UO2 pellet showed gradual polarization of the cathode to higher cathodic values with time within a band of +0.250 V and 0.000 V vs (Na-Ca)/(Na+,Ca2+). No ternary intermediate compounds of the type Ca-U-O or Na-U-O or sub-oxides were observed in the partially reduced samples. Unlike in pure CaCl2 melt at 1173 K, the consumption of graphite anode and the carbon contamination of the melt were found to be minimum in the present study. Based on the experimental data, a probable mechanism of electrochemical reduction of UO2 to U in molten CaCl2-48mol% NaCl has been proposed.

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confidence: 99%

Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt

Vishnu¹,

Sanil²,

Panneerselvam³

et al. 2013

J. Electrochem. Soc.

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“…The difference in the reduction potential between UO 2 and Li 2 O is small (70 mV) 48 . In practice, overvoltage is required to achieve high electrolysis performance.…”

Section: Recovery Of Fps and Their Influence On The Restoration Proce...mentioning

confidence: 99%

“…The difference in the reduction potential between UO 2 and Li 2 O is small (70 mV). 48 In practice, overvoltage is required to achieve high electrolysis performance. Increasing the voltage often leads to the cell potential exceeding the required electrochemical window.…”

Section: Highly Enhanced Reduction Of Rare Earth and Zirconium Oxidesmentioning

confidence: 99%

Recoveryof actinidesand fission products from spent nuclear fuel via electrolytic reduction: Thematic overview

Галашев

2021

Intl J of Energy Research

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Summary Spent nuclear fuel (SNF) from modern light water or thermal reactors containing uranium oxide with small concentrations of plutonium and other actinide oxides is converted into metal by the electrolytic reduction. The obtained metal must be subjected to further processing (electrorefining). This review reflects the achievements in development SNF electrolytic processing, concepts of the technological operations, and a model describing the electrochemical process. The technological scheme for the electrochemical reduction of SNF and MOX fuel is considered. The complexity of a carbon anode application in the process of UO2 electrolytic reduction is reflected. The reduction processes of alkali, alkaline earth (AE), and rare earth metal oxides as well as oxide compounds of zirconium are demonstrated. The reduction of lanthanum oxide and oxy‐chloride to the metallic form by adding metallic nickel to the molten salt is discussed. The solubility of Li2O in molten salts is interpreted depending on the amount of dissolved alkali and AE metal chlorides. The considered pyroprocessing technology enables a much greater release of the energy accumulated in uranium ore, and recycling all actinides allows reducing significantly the amount of nuclear waste and the time it must be isolated.

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“…The experimental approach is to investigate a LiCl salt contaminated with cesium chloride (CsCl). LiCl was selected for the oxide reduction electrolyte to simplify the system because only 1wt% (U.S.) [5] and 3wt% (South Korea) [7] of the LiCl-Li 2 O electrolyte is lithium oxide (Li 2 O). To further simplify the system non-radioactive CsCl was selected to represent Group I actinides because of its abundant accumulation in the oxide reduction electrolyte [5].…”

Section: Approachmentioning

confidence: 99%

Fission Product Separation from Pyrochemical Electrolyte by Cold Finger Melt Crystallization

Versey¹

2013

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This work contributes to the development of pyroprocessing technology as an economically viable means of separating used nuclear fuel from fission products and cladding materials. Electrolytic oxide reduction is used as a head-end step before electrorefining to reduce oxide fuel to metallic form. The electrolytic medium used in this technique is molten LiCl-Li 2 O. Groups I and II fission products, such as cesium (Cs) and strontium (Sr), have been shown to partition from the fuel into the molten LiCl-Li 2 O.Various approaches of separating these fission products from the salt have been investigated by different research groups. One promising approach is based on a layer crystallization method studied at the Korea Atomic Energy Research Institute (KAERI). Despite successful demonstration of this basic approach, there are questions that remain, especially concerning the development of economical and scalable operating parameters based on a comprehensive understanding of heat and mass transfer. This research explores these parameters through a series of experiments in which LiCl is purified, by concentrating CsCl in a liquid phase as purified LiCl is crystallized and removed via an argon-cooled cold finger. All experiments were conducted in an inert argon atmosphere. The experimental LiCl-CsCl operating temperature was 650˚C with a cold finger temperature held at the freezing temperature of LiCl (≈605˚C). Molten salt and cold finger exhaust temperatures were measured throughout experiments and argon cooling gas flow was controlled manually via a needle valve. The varied parameters of interest were initial contaminant concentration, cold finger cooling rate, and separation time. CsCl concentration was measured via Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) for purified LiCl crystals and concentrated LiCl-CsCl bulk.Preliminary results revealed that co-deposition of CsCl along with LiCl crystal formation due to slightly non-equilibrium mass transport is a problem that must be minimized. Analysis of experiments with initial 5 wt% CsCl concentration showed that for an experimental matrix of varying cold finger coolant flow rates (7.4, 9.8, 12.3, and 14.9 L/min) and separation times (5, 10, 15, and 30 min), the optimal cooling flow rate and separation time are 14.9 L/min and 15 min, respectively, producing a 0.33 wt% CsCl crystal purity at a production rate of 0.36 g/min. Experimental results for initial concentrations of 1, 3, and 7.5 wt% CsCl at the aforementioned coolant flow rates for separation times of 15 min were analyzed and showed iv that as initial bulk concentration increased from 1 to 7.5 wt% CsCl, the change in purified crystal concentration for experiments was less than 0.5 wt% CsCl for all but one data point.The optimal result of the initial 5 wt% CsCl experiments along with results of initial 1, 3, and 7.5 wt% CsCl bulk concentration experiments were used to predict a scale-up scenario that provided a potential separation rate and purity of 136 g/hr and 0.24 wt% CsCl, respectively, to provide in...

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Electrolytic reduction behavior of U3O8 in a molten LiCl–Li2O salt

Cited by 33 publications

References 23 publications

Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt

Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt

Recoveryof actinidesand fission products from spent nuclear fuel via electrolytic reduction: Thematic overview

Fission Product Separation from Pyrochemical Electrolyte by Cold Finger Melt Crystallization

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Electrolytic reduction behavior of U3O8 in a molten LiCl–Li2O salt

Cited by 33 publications

References 23 publications

Mechanism of Direct Electrochemical Reduction of Solid UO2to Uranium Metal in CaCl2-48mol% NaCl Melt

Mechanism of Direct Electrochemical Reduction of Solid UO2to Uranium Metal in CaCl2-48mol% NaCl Melt

Recoveryof actinidesand fission products from spent nuclear fuel via electrolytic reduction: Thematic overview

Fission Product Separation from Pyrochemical Electrolyte by Cold Finger Melt Crystallization

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Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt

Mechanism of Direct Electrochemical Reduction of Solid UO₂to Uranium Metal in CaCl₂-48mol% NaCl Melt