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Multi-scale gas transport modelling for the EC FORGE project

Published online by Cambridge University Press:  02 January 2018

A. E. Bond ,
K. E. Thatcher  and
S. Norris
A. E. Bond*
Affiliation:
Quintessa Limited, 633/635 Birchwood Boulevard, Birchwood, Warrington, Cheshire, WA3 7QU, UK
K. E. Thatcher
Affiliation:
Quintessa Limited, 633/635 Birchwood Boulevard, Birchwood, Warrington, Cheshire, WA3 7QU, UK
S. Norris
Affiliation:
Radioactive Waste Management Limited, Building 587, Curie Avenue, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0RH, UK
*
*E-mail: [email protected]
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Abstract

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The generation and migration of gas within and around proposed radioactive waste disposal facilities is potentially a safety critical process. A safety case for a facility that generates significant quantities of gas (e.g. through metal corrosion or radiolysis) will require demonstration that gas migration around and away from the waste is sufficiently understood and will not breach the safety case for the facility. Models can be used to understand the likely hydraulic evolution of such a disposal facility, but the models need to consider processes over a range of scales. A whole repository may extend over kilometres, with individual disposal cells at the scale of tens of metres and features which provide pathways for gas migration on a centimetre scale. All of these features may be significant from a safety perspective and capturing the impact of all of these features in a single model is a significant challenge.

This paper presents an approach to tackling this multi-scale problem, which allows the whole repository to be modelled in a computationally efficient manner. The approach involves identifying areas within the modelled domain that show very similar behaviour, and representing these areas with sub-models, so that small-scale features are retained, but computational overhead is decreased by using the results in more than one location in the model domain. The approach allowed a model of a whole repository to be run on a single processor core, whilst maintaining the small-scale features of the system. The model results were compared against more conventional upscaling techniques and show the advantage of a more detailed representation of small-scale features. The model results reflect the conceptual understanding of how gas would migrate in a repository.

Keywords

radioactive wastegasnumerical modellingmulti-scale
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 6 , November 2015 , pp. 1251 - 1263
Creative Commons
Creative Common License - CCCreative Common License - BY
Copyright © The Mineralogical Society of Great Britain and Ireland 2015. This is an open access article, distributed under the terms of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2015

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