Utilising DualEELS to probe the nanoscale mechanisms of the corrosion of Zircaloy-4 in 350 °C pressurised water

Annand, K. J., MacLaren, I. and Gass, M. (2015) Utilising DualEELS to probe the nanoscale mechanisms of the corrosion of Zircaloy-4 in 350 °C pressurised water. Journal of Nuclear Materials, 465, pp. 390-399. (doi:10.1016/j.jnucmat.2015.06.022)

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Abstract

Characterisation of materials utilised for fuel cladding in nuclear reactors prior to service is integral in order to understand corrosion mechanisms which would take place in reactor. Zircaloy-4 is one such material of choice for nuclear fuel containment in Pressurised Water Reactors (PWRs). In particular, the metal-oxide interface has been a predominant focus of previous research, however, due to the complex oxidation process of zirconium cladding, there is still no clear understanding of what is present at the interface. Using Scanning Transmission Electron Microscopy (STEM) and Dual Electron Energy Loss Spectroscopy (DualEELS), we have studied the corrosion of this material under conditions similar to those that could be encountered in service. It is shown that under all conditions, whether during faster oxidation in the early stages, slow growth just prior to the transition to a new growth regime, or in the faster growth that happens after this transition, the surface of the metal below the scale is loaded with oxygen up to around 33 at%. Approaching transition, in conditions of slow growth and slow oxygen supply, an additional metastable suboxide is apparent with a thickness of tens of nm. By studying changes in both chemical composition and dielectric function of the material at the oxide scale – metal interface with nanometre resolution, quantitative mapping could be achieved, clearly showing that this is a suboxide composition of ZrO and a Zr oxidation state close to +2.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:MacLaren, Dr Ian and Annand, Ms Kirsty
Authors: Annand, K. J., MacLaren, I., and Gass, M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Journal of Nuclear Materials
Publisher:Elsevier
ISSN:0022-3115
ISSN (Online):1873-4820
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in Journal of Nuclear Materials 465:390-399
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
642131Doctoral Training Grant 2013 - 2017Mary Beth KneafseyEngineering & Physical Sciences Research Council (EPSRC)EP/L50497X/1RSI - RESEARCH STRATEGY & INNOVATION