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A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

Abstract

This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elasto-plastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because of decreasing thermal stress.

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Acknowledgments

Funding for the work performed by the LBNL research team and the first author was provided to LBNL by the US Department of Energy under Contract No. DE-AC02-05CH11231. The publisher, by accepting the article for publication, acknowledges that the US Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. Funding for modeling work by other research teams was provided by Japanese Atomic Energy Agency (JAEA), the Finnish Research Programme on Nuclear Waste Management (KYT) and Posiva, the Swedish Nuclear Power Inspectorate (SKI), and the National Nature Science Foundation of China under grant No. 50709036 and 40520130315. It is emphasized that the views expressed in this paper are solely those of the authors and cannot necessarily be taken to represent the views of any of the organizations listed above.

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Correspondence to Jonny Rutqvist.

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Rutqvist, J., Bäckström, A., Chijimatsu, M. et al. A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories. Environ Geol 57, 1313–1324 (2009). https://doi.org/10.1007/s00254-008-1536-1

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  • DOI: https://doi.org/10.1007/s00254-008-1536-1

Keywords

  • Coupled THM
  • Nuclear waste repository
  • Excavation disturbed zone
  • Damage
  • Permeability