Atomic Scale Cryogenic Microscopy to Understand the Degradation of Vitrified Nuclear Waste

Session

Poster Session Three

Authors

Ms Siobhan Kingsley (1), Prof Baptiste Gault (2, 1), Prof Mary Ryan (1), Dr Shelly Conroy (1)

Affiliations

1. Department of Materials, London Centre for Nanotechnology, Imperial College London
2. Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str.1

Keywords

Abstract text

Corrosion is a cross-disciplinary and complex problem that in the context of nuclear waste glass, could pose a significant environmental and societal impact; contributing to the public perception of nuclear technology. Understanding the mechanisms of materials degradation in complex environments is critical to develop appropriate protection measures, for risk models for long-term safe storage of HLW. Historically, durability assessments have been extrapolated from short-term corrosion, dissolution and leaching laboratory experiments and benchmarked against long-term natural testing on glasses, referred to as analogues. Several analogue glasses have been identified over the last half century including volcanic, medieval and roman. In recent years, 1500-year-old Broborg hillfort glass has shown to be more representative of most nuclear waste glass, as a long-term alteration analogue for Low Activity Waste [1].  

 

This project seeks to use ancient synthetic and natural volcanic glasses to study the long-term degradation of glass. This will support the characterisation and understanding of the long-term chemical stability of glasses, with respect to the transport of glass components and ground water. Initial analysis will be performed via transmission electron microscopy (TEM) to characterise the alteration layers of any ancient synthetic and/or volcanic glasses; to gain insight into the mechanisms of glass alteration. TopoTEM and Py4DSTEMopen-source software will allow for the computation and visualise polarised imagery to directly map displacements and deformations at atomic resolution via Scanning Transmission Electron Microcopy (STEM)[2] [3]. Using cryogenic focused ion beam (FIB) and atom-probe tomography (APT) microscopy, and in collaboration with Dr Carolyn Pearce at iDREAM, Pacific Northwest National Laboratory, along with WSU, NIST and the Smithsonian; I will build on the efforts of Schreiber and Pereato refine the techniques and methodologies for atomic-scale comparison of ancient glass samples with pristine materials to elucidate corrosion mechanisms [4]. 

References

1. J. L. Weaver, C. I. Pearce, R. Sjöblom, J. S. McCloy, M. Miller, T. Varga, B. W. Arey, M. A. Conroy, D. K. Peeler, R. J. Koestler, P. T. DePriest, E. P. Vicenzi, E. järthner-Holdar, E. Ogenhall and A. A. Kruger, "Pre-viking Swedish hillfort glass: A prospective long-term alteration analogue for vitrified nuclear waste," International Journal of Applied Glass Science, vol. 9, no. 4, pp. 540-554, 2018. 
2. E. N. O'Connell, K. Moore, E. McFall, M. Hennessy, E. Moynihan, U. Bangert and M. Conroy, "TopoTEM: A Python Package for Quantifying and Visualizing Scanning Transmission Electron Microscopy Data of Polar Topologies," Microscipy and Microanalysis, vol. 28, no. 4, pp. 1444-1452, 2022. 
3. B. Savitzky, S. Zeltmann, L. Hughes, S. Z. ,. P. M. P. ,. T. P. H.G. Brown, E.S.Barnard, J. Donohue, L. DaCosta, E. Kennedy, Y. Xie, M. Janish, M. Schneider, P. Herring, C. Gopal, A. Anapolsky, R. Dhall, K. Bustillo and P. Ercius, "py4DSTEM: A Software Package for Four-Dimensional Scanning Transmission Electron Microscopy Data Analysis," MIcroscopy and Microanalysis, vol. 27, no. 4, pp. 712-743, 2021. 
4. D. Schreiber, D. Perea, J. Ryan, J. Evans and J. Vienna, "A method for site-specific and cryogenic specimen fabrication of liquid/solid interfaces for atom probe tomorgraphy," Ultramicroscopy, no. 194, pp. 89-99, 2018.