http://www.koreascience.or.kr:80/article/JAKO201127250029099.pdf

Pyroprocessing technology development at kaeri

Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution–electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

The electrochemical reduction processes of solid compounds in high temperature molten salts

1. Introduction 28632. Theoretical Considerations 28643. Electro-deoxidation under Controlled Voltage orPotential 28663.1. Earlier Attempts to Describe the ReductionMechanism 28663.2. Three-Phase Interline (3PI) PropagationModels 28673.3. Alkali Ternary Oxides Intermediates 28673.3.1. Niobium Oxide 28673.3.2. Tantalum Oxide 28683.3.3. Chromium Oxide 28683.3.4. Titanium Oxide 28683.3.5. Zirconium Oxide 28703.3.6. Tungsten Oxide 28703.3.7. Aluminum Oxide 28703.4. Electro-deoxidation of Mixed Oxides andOxide Solid Solutions 28713.5. Attempts to Use Inert Anode 28734. Cyclic Voltammetry 28744.1. Understanding the Cathodic ReductionReactions 28744.2. Determining the Optimum Operation Po-tential 28764.3. Exploring the Surface Phenomenon 28774.4. Studying the Complex Side Processes andDetecting the High Temperature Intermedi-ate Phases 28774.5. Providing Direct Insights into the Kinetics ofElectrode Reactions 28785. Electro-deoxidation under Constant CurrentChronopotentiometry 28796. Summary and Future Direction 2882Author Information 2883Corresponding Author 2883Notes 2883Biographies 2883References 2884

DC Voltammetry of Electro-deoxidation of Solid Oxides

http://koreascience.or.kr:80/article/JAKO201021452661426.pdf

Status of pyroprocessing technology development in KOREA

Electrochemical processing of spent nuclear fuels: An overview of oxide reduction in pyroprocessing technology

Pyroprocessing technology has been actively developed at Korea Atomic Energy Research Institute (KAERI) to meet the necessity of addressing spent fuel management issue. This technology has advantages over aqueous process such as less proliferation risk, treatment of spent fuel with relatively high heat and radioactivity, and compact equipments. This paper describes the pyroprocessing technology development at KAERI from head-end process to waste treatment. The unit process with various scales has been tested to produce the design data associated with scale-up. Pyroprocess integrated inactive demonstration facility (PRIDE) was constructed at KAERI and it began test operation in 2012. The purpose of PRIDE is to test the process regarding unit process performance, remote operation of equipments, integration of unit processes, scale-up of process, process monitoring, argon environment system operation, and safeguards-related activities. The test of PRIDE will be promising for further pyroprocessing technology development.

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Current Status of Pyroprocessing Development at KAERI

Electrochemical reduction behavior of U3O8 powder in a LiCl molten salt

The concept of a novel electrochemical reduction process for the treatment of spent nuclear fuels in Li2O-LiCl molten salt was proposed and fresh tests using U3O8 powder were carried out to elucidate the reaction mechanism and verify the feasibility of the process. Electrolysis of Li2O and reduction of U3O8 powder took place simultaneously at the cathode part of the electrolysis cell via a catalytic EC mechanism and the conversion of U3O8 to U metal was more than 99%.

Jin-Mok Hur

Papers

Current Status of Pyroprocessing Development at KAERI

Electrochemical reduction behavior of U3O8 powder in a LiCl molten salt

Metallization of U3O8 via catalytic electrochemical reduction with Li2O in LiCl molten salt

Electrochemical reduction behavior of a highly porous SIMFUEL particle in a LiCl molten salt

Hot corrosion behavior of Ni-base alloys in a molten salt under an oxidizing atmosphere