Brown, LD;
Abdulaziz, R;
Tjaden, B;
Inman, D;
Brett, DJL;
Shearing, PR;
(2016)
Investigating microstructural evolution during the electroreduction of UO2 to U in LiCl-KCl eutectic using focused ion beam tomography.
Journal of Nuclear Materials
, 480
pp. 355-361.
10.1016/j.jnucmat.2016.07.036.
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Abstract
Reprocessing of spent nuclear fuels using molten salt media is an attractive alternative to liquid-liquid extraction techniques. Pyroelectrochemical processing utilizes direct, selective, electrochemical reduction of uranium dioxide, followed by selective electroplating of a uranium metal. Thermodynamic prediction of the electrochemical reduction of UO2 to U in LiCl-KCl eutectic has shown to be a function of the oxide ion activity. The pO2− of the salt may be affected by the microstructure of the UO2 electrode. A uranium dioxide filled “micro-bucket” electrode has been partially electroreduced to uranium metal in molten lithium chloride-potassium chloride eutectic. This partial electroreduction resulted in two distinct microstructures: a dense UO2 and a porous U metal structure were characterised by energy dispersive X-ray spectroscopy. Focused ion beam tomography was performed on five regions of this electrode which revealed an overall porosity ranging from 17.36% at the outer edge to 3.91% towards the centre, commensurate with the expected extent of reaction in each location. The pore connectivity was also seen to reduce from 88.32% to 17.86% in the same regions and the tortuosity through the sample was modelled along the axis of propagation of the electroreduction, which was seen to increase from a value of 4.42 to a value of infinity (disconnected pores). These microstructural characteristics could impede the transport of O2− ions resulting in a change in the local pO2− which could result in the inability to perform the electroreduction.
| Type: | Article |
|---|---|
| Title: | Investigating microstructural evolution during the electroreduction of UO2 to U in LiCl-KCl eutectic using focused ion beam tomography |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jnucmat.2016.07.036 |
| Publisher version: | http://doi.org/10.1016/j.jnucmat.2016.07.036 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1545545 |
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