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close to values of the undisturbed host rock may be attained although, locally, the porosity may remain
greater than in the undisturbed rock. In the very long-term, a reconsolidation may occur along
fissures and/or micro-fissured zones.
Investigations concerning gas transfer along the EDZ
Work in the framework of NF-PRO on gas transfer along the EDZ focussed on the characterisation
of gas transfer properties, in particular gas permeability, gas threshold pressure, capillary curves of
the EDZ before, during and after hydro-mechanical self-sealing. Also, studies were performed to
investigate the consequences of impairments due to an excessive gas pressure. These investigations
focussed on gas transfer processes in plastic and indurated clay and rock salt. Results obtained have
demonstrated that fast self-sealing of the EDZ occurs in plastic clays. At the microstructural level,
preferential pathways for gas migration may exist. However, effective hydro-mechanical selfsealing
is expected to occur relatively rapidly during resaturation, in particular before significant
gas pressure build-up occurs.
4.5 Advances in research related to process couplings and integration in Performance Assessment
NF-PRO has carried out integrated analyses of the near-field evolution. These analyses have been
performed for different reference disposal concepts and host rocks and have confirmed that the
near-field displays a high degree of robustness and redundancy. Results from these evaluations are
summarised in [5] and have allowed identifying remaining key uncertainties and priority areas in
future research for these systems.
5. Conclusion
Experimental studies and modelling work by NF-PRO have provided new insights in and information
on key process affecting the overall performance of the near-field system. NF-PRO has a major
strategic impact on European disposal-related research since the Integrated Project has effectively
contributed to strengthening the scientific-technical basis for geological disposal.
References
[1] Grambow et al. 2008: RTDC-1 Final Synthesis Report, Dissolution and release from the
waste matrix. EU NF-PRO Project FI6W-CT-2003-02389.
[2] Arcos, D., Hernán, P., De La Cruz, B., Herbert, H.-J., Savage, D., Smart, N.R., Villar, M.V.,
Van Loon, L.R. 2008: NF-PRO RTDC-2 Synthesis Report, Deliverable (D-N°:D2.6.4) EU
NF-PRO Project FI6W-CT-2003-02389.
[3] Villar et al. 2008: RTDC-3 Synthesis Report. EU NF-PRO Project FI6W-CT-2003-02389.
[4] Aranyossy J-F., Mayor, J.C., Marschall, & Plas, F. 2008: EDZ development and evolution.
RTDC-4 Synthesis Report. EU NF-PRO Project FI6W-CT-2003-02389.
[5] Johnson, L. et al. 2008: RTDC-5 Synthesis Report, Deliverable (D-N°:5.2.3), EU NF-PRO
Project FI6W-CT-2003-02389.
[6] Poinssot, C. et al. Final report of the European Project Spent Fuel Stability under Repository
Conditions. CEA-R-6093. ISSN 0429-3460, 2005, pp. 103.
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