NAGRA Opalinus Clay (…002 - Version 1
FEP 13.2.1 Seal performance (during and after swelling)

The performance of seals is influenced by i) poor or incomplete emplacement of sealing material, ii) insufficient or heterogeneous swelling, iii) chemical degradation, iv) insufficient sealing of EDZ, v) damages induced by hydraulic overpressures (gas production, tunnel convergence) and geological events (neo-tectonic activity). Optionally, seals may be designed to be gas-permeable, in which case the effects of excessive pressure build-up due to gas generation would be mitigated.