Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.746240
Title: Electrochemical reduction of metal oxides in molten salts for nuclear reprocessing
Author: Abdulaziz, R.
ISNI:       0000 0004 7230 6201
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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Abstract:
This thesis examines the electrochemical reduction of metal oxides in molten salts for nuclear reprocessing applications. The objective of this research is to characterise and understand the direct electrochemical reduction of UO2 to U metal in a LiCl-KCl molten salt eutectic, as part of the nuclear pyroprocessing scheme, following a similar approach to the FFC Cambridge for the reduction of TiO2 to Ti metal. The voltammetric behaviour of reduction processes of metal oxides were evaluated using electroanalytical techniques such as cyclic voltammetry and chronoamperometry on different precursor types, such as thermally grown thin oxide films, metallic cavity electrodes, and ‘a fluidised cathode’, a novel process that was developed within this work. Material was characterised before and after the electroanalytical experiments using scanning electron microscopy, X-ray energy dispersive spectroscopy and X-ray diffraction. Predominance phase diagrams, using recent thermodynamic data, for metal-molten salt systems, relating the potential to the negative logarithm of the activity of O2− ions (E-pO2−), were produced for the range of spent nuclear materials in both LiCl-KCl and NaCl-KCl. The bulk of this research was on investigating the electrochemical reduction of WO3 to W metal. Tungsten was selected as a chemical surrogate for uranium to investigate specific process parameters. Nonetheless, tungsten is an important and desirable refractory metal, and the electrochemical route for producing it of high purity might prove viable. The electrochemical reduction of UO2 to U metal using the fluidised cathode process was investigated. Voltammetry studies were conducted, and alongside a predominance diagram that was constructed, the reaction path-way was studied, and a Faradaic efficiency was established. The fluidised cathode is a robust, three-phase, high efficiency process. It was studied here for the electrochemical reduction of WO3 and UO2, however, it is likely applicable for other spent fuel oxides, and in the production of refractory metals.
Supervisor: Brett, D. ; Shearing, P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.746240  DOI: Not available
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