Simultaneous gas and water flow in a damage-susceptible bedded argillaceous rock

Abstract of the journal article published in Canadian Geotechnical Journal: April 2014

Author(s):
Son Nguyen

Abstract:

In many countries, including Canada, sedimentary rock formations are being considered as candidates for the long-term management of radioactive wastes. These formations possess desirable characteristics (such as very low permeability) that would limit the movement of radionuclides from the wastes. However, gases that could be generated inside the repository were identified as a subject requiring further investigations, since they could affect the host rock performance. Gases like hydrogen, hydrocarbons, or carbon dioxide could be generated and released as a result of corrosion of the metallic components of the waste or the containers, and by thermal or microbial degradation of organic components within the waste, the backfill or the surrounding clay. These gases may pressurize sealed areas, form micro- and/or macro-cracks, and become carriers for volatile radionuclides.

The authors use experimental data from the injection of gas in a test tunnel (inside an underground research laboratory in Switzerland) to develop a mathematical model. The model can predict the extent and characteristics of the damage zone in the rock, and successfully simulate the influence of that zone on the simultaneous flow of gas and water in the host rock. This work provides CNSC staff with a tool to independently assess future proposal for geological disposal repositories.