Reoxidation of uranium metal immersed in a Li 2 O-LiCl molten salt after electrolytic reduction of uranium oxide

Abstract We present our findings that uranium (U) metal prepared by using the electrolytic reduction process for U oxide (UO 2 ) in a Li 2 O–LiCl salt can be reoxidized into UO 2 through the reaction between the U metal and Li 2 O in LiCl. Two salt types were used for immersion of the U metal: one was the salt used for electrolytic reduction, and the other was applied to the unused LiCl salts with various concentrations of Li 2 O and Li metal. Our results revealed that the degree of reoxidation increases with the increasing Li 2 O concentration in LiCl and that the presence of the Li metal in LiCl suppresses the reoxidation of the U metal.

[1]  K. M. Goff,et al.  ELECTROCHEMICAL PROCESSING OF USED NUCLEAR FUEL , 2011 .

[2]  Han-Soo Lee,et al.  Electrochemical reduction behavior of U3O8 powder in a LiCl molten salt , 2010 .

[3]  Jin-Mok Hur,et al.  Electrochemical reduction behavior of a highly porous SIMFUEL particle in a LiCl molten salt , 2012 .

[4]  Tadashi Inoue,et al.  Electrochemical Reduction of UO2 in Molten CaCl2 or LiCl , 2006 .

[5]  S. P. Henslee,et al.  EBR-II spent fuel treatment demonstration project status , 1998 .

[6]  Derek J. Fray,et al.  Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride , 2000, Nature.

[7]  Tadashi Inoue,et al.  State of the Art of Pyroprocessing Technology in Japan , 2011 .

[8]  Shelly X. Li,et al.  Separation and Recovery of Uranium Metal from Spent Light Water Reactor Fuel Via Electrolytic Reduction and Electrorefining , 2010 .

[9]  G. Chen,et al.  Solid state reactions: an electrochemical approach in molten salts , 2008 .

[10]  Jin-Mok Hur,et al.  A conductive oxide as an O2 evolution anode for the electrolytic reduction of metal oxides , 2015 .

[11]  E. Choi,et al.  Electrochemical reduction of porous 17 kg uranium oxide pellets by selection of an optimal cathode/anode surface area ratio , 2011 .

[12]  Jin-Mok Hur,et al.  Effect of the UO2 form on the electrochemical reduction rate in a LiCl–Li2O molten salt , 2013 .

[13]  K. Mohandas.  Direct electrochemical conversion of metal oxides to metal by molten salt electrolysis: a review , 2013 .

[14]  G. Panneerselvam,et al.  Factors Influencing the Direct Electrochemical Reduction of UO2 Pellets to Uranium Metal in CaCl2-48 mol% NaCl Melt , 2013 .

[15]  B. Raj,et al.  Development of Pyrochemical Reprocessing for Spent Metal Fuels , 2011 .

[16]  Lothar Koch,et al.  DEVELOPMENT OF PYROPROCESSING AND ITS FUTURE DIRECTION , 2008 .

[17]  Han-Soo Lee,et al.  STATUS OF PYROPROCESSING TECHNOLOGY DEVELOPMENT IN KOREA , 2010 .

[18]  Han-Soo Lee,et al.  Underpotential deposition of Li in a molten LiCl–Li2O electrolyte for the electrochemical reduction of U from uranium oxides , 2010 .

[19]  D. Fray,et al.  DC voltammetry of electro-deoxidation of solid oxides. , 2013, Chemical reviews.

[20]  E. Choi,et al.  Electrochemical processing of spent nuclear fuels: An overview of oxide reduction in pyroprocessing technology , 2015 .

[21]  Wei Xiao,et al.  The electrochemical reduction processes of solid compounds in high temperature molten salts. , 2014, Chemical Society reviews.

[22]  Han-Soo Lee,et al.  Korean Pyrochemical Process R&D activities , 2011 .

[23]  E. Choi,et al.  Production of uranium metal via electrolytic reduction of uranium oxide in molten LiCl and salt distillation , 2015, Journal of Radioanalytical and Nuclear Chemistry.

[24]  Jin-Mok Hur,et al.  Electrochemical behavior of a platinum anode for reduction of uranium oxide in a LiCl molten salt , 2009 .

[25]  Shelly X. Li,et al.  Electrolytic Reduction of Spent Nuclear Oxide Fuel as Part of an Integral Process to Separate and Recover Actinides from Fission Products , 2006 .

[26]  J. J. Laidler,et al.  Development of pyroprocessing technology , 1997 .

[27]  Y. Sakamura,et al.  Development of Pyro-processing Fuel Cycle Technology for Closing Actinide Cycle , 2012 .

[28]  J. Poignet,et al.  Measurement of the activity of lithium in dilute solutions in molten lithium chloride between 650°C and 800°C , 1990 .

[29]  R. Sudha,et al.  Mechanism of Direct Electrochemical Reduction of Solid UO2 to Uranium Metal in CaCl2-48mol% NaCl Melt , 2013 .

[30]  E. Choi,et al.  Use of a single fuel containment material during pyroprocessing tests , 2015 .

[31]  J. P. Ackerman,et al.  Treatment of wastes in the IFR fuel cycle , 1997 .