A 3D Geological Fault Model for Characterisation of Geological Faults at the Proposed Site for the Wylfa Newydd Nuclear Power Plant, Wales

  • Matthew FreeEmail author
  • Ben GilsonEmail author
  • Jason Manning
  • Richard HoskerEmail author
  • David Schofield
  • Martin Walsh
  • Mark Doherty
Conference paper


Nuclear energy is an important part of a sustainable, economic and secure energy balance for the United Kingdom (UK). Horizon Nuclear Power commissioned Arup to provide seismic hazard assessment (SHA) consultancy services for the proposed Wylfa Newydd Nuclear Power Station in Anglesey, Wales, UK. Advanced Boiling Water Reactors are proposed to provide at least 5400 MW, enough to power around 10 million homes. The SHA comprises a probabilistic seismic hazard assessment of ground motion, a tsunami hazard assessment and a capable faulting assessment. The capable faulting assessment included thoroughly identifying and investigating geological faults at the site, with due consideration of the geological, seismological and tectonic setting. The objective of the capable faulting assessment was to demonstrate that faults are not capable of surface rupture within the current tectonic setting. Should evidence suggest that faults with the potential to affect the safety of the nuclear installation are capable, IAEA guidance dictates that an alternative site shall be considered. A project 3D Geological Fault Model was developed to characterise geological faulting at the site for the capable faulting assessment. A systematic methodology that incorporates expert judgment was developed and applied to the investigation and correlation of geological faults between site investigation data points. A total of 36 geological faults were mapped across the site and three fault sets were identified. Absolute age dating of the fault gouge on a representative selection of samples was subsequently undertaken to demonstrate that faults at the site are not capable in accordance with IAEA guidelines.


Capable faulting Nuclear industry Geological modelling Anglesey Surface rupture 



A project of this scale is truly a team effort. The authors wish to acknowledge the contribution to the overall success of the project the following: team members from the ground investigation contractors Structural Soils Ltd. and Fugro Seacore, and Horizon’s geotechnical specialist Atkins Ltd. The BGS’s logging geologists Graham Leslie, Rachael Ellen, Martin Gillespie and Katie Whitbread. David Schofield publishes with the permission of the Executive Director, British Geological Survey. Arup’s project team including Adrian Collings, Robin Lee, Crispin Oakman and Ziggy Lubkowski. Members of Horizon project team, and their Independent Peer Review team for their supportive and constructive comments.


  1. Bradley, S., Milne, G., Teferle, F.N., Bingley, R., Orliac, E.: Glacial isostatic adjustments of the British Isles: new constraints from GPS measurements of crustal motion. Geophys. J. Int. 178, 14–22 (2009)CrossRefGoogle Scholar
  2. Cooper, M.R., Anderson, H., Walsh, J.J., Van Dam, C.L., Young, M.E., Earls, G., Walker, A.: Paleogene Alpine tectonics and Icelandic plume-related magmatism and deformation in Northern Ireland. J. Geol. Soc. 169, 29–36 (2012)CrossRefGoogle Scholar
  3. Greenly, E.: Memoirs of the Geological Survey—Anglesey (1919)Google Scholar
  4. Gillespie, M.R., Barnes, R.P., Milodowski, A.E.: British Geological Survey Scheme for Classifying Discontinuities and Fillings. British Geological Survey Research Report, RR/10/05. 56 pp (2011)Google Scholar
  5. Harris, C.: Glacially deformed bedrock at Wylfa head, Anglesey. Geol. Soc. Eng. Geol. Spec. Pub. 7, 135–142 (1991)Google Scholar
  6. HM Government: Long-Term Nuclear Energy Strategy. BIS/13/630 (2013)Google Scholar
  7. Hunter, A., Easterbrook, G.: The Geological History of the British Isles. The Open University, Milton Keynes (2004)Google Scholar
  8. International Atomic Energy Agency (IAEA): Seismic Hazards in Site Evaluation for Nuclear Installations. IAEA Specific Safety Guide Series No. SSG-9, IAEA, Vienna (2010)Google Scholar
  9. International Atomic Energy Agency (IAEA): Site Evaluation for Nuclear Installations. IAEA Specific Safety Standard Series No. NS-R-3 (Rev. 1), IAEA, Vienna (2016)Google Scholar
  10. Institute of Geological Sciences: Anglesey 1:50,000 Scale Solid and Drift Geology Map. Prepared by Dunham, K, Geological Survey of Great Britain (1974a)Google Scholar
  11. Institute of Geological Sciences: Anglesey 1:50,000 Scale Solid Geology Map. Prepared by Dunham, K, Geological Survey of Great Britain (1974b)Google Scholar
  12. Mallard, D.J., Higginbottom, I.E., Wood, R.M., Skipp, B.O.: Recent developments in the methodology of seismic hazard assessment. In: Dexter-Smith, R. (ed.) Civil Engineering in the Nuclear Industry. Thomas Telford, London (1991)Google Scholar
  13. ONR: Safety Assessment Principles for Nuclear Facilities. Revision 0 (2014a)Google Scholar
  14. ONR: ONR Guide, External Hazards, Nuclear Safety Technical Assessment Guide, NS-TAST-GD-013 Revision 5 (2014b)Google Scholar
  15. Phillips, E.: The Geology of Anglesey, North Wales: Project Scoping Study. British Geological Survey Internal Report, IR/09/05 (2010)Google Scholar
  16. Virtalis: Geovisionary. Version used: 3.0.15 (2016)Google Scholar
  17. Woodcock, N.H., Strachan, R.A.: Geological History of Britain and Ireland, 2nd edn. London, Blackwell (2012)CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.ArupLondonUK
  2. 2.ArupNottinghamUK
  3. 3.British Geological SurveyEdinburghUK
  4. 4.Horizon Nuclear PowerGloucesterUK

Personalised recommendations