GAM investigates the behaviour of gas in the far field (geosphere) surrounding a radioactive waste repository. Gases, such as hydrogen (H2), methane (CH4) and carbon dioxide (CO2) can be generated by anaerobic corrosion and microbial degradation of metallic materials and organic wastes disposed in geological repositories.

The Gas Migration Test (GMT) investigates the movement of these gases in the near field (the engineered barrier system and the immediately surrounding rock), while GAM project examined the behaviour of gas in the far field.

The study of gas migration is important in assessing the overall behaviour of a repository because:

• pressure build-up due to gas production might cause failure of the EBS/natural barriers.
  
  
• radionuclides in the gaseous phase might migrate from the emplacement caverns via geological discontinuities (such as shear zones) to the biosphere.
  
  
• contaminated water in the caverns might be pressed into the geosphere due to the overpressure in the caverns.
  

The overall aim of the GAM project was to understand and analyse the transport of water and gas in a complex shear zone.

GAM Objectives

• Visualisation of channelling on the lab- and field scale (internal heterogeneity of shear zones).
  
  
• Up-scaling procedures and effective parameters for two-phase flow processes in fractured media.
  
  
• Developing consistent conceptual/numerical models for (single phase) solute and gas transport.

The research was split between tests carried out in a laboratory environment, in-situ field tests carried out at the GTS and modelling studies. This integrated research forms the basis of the GAM concept.

Lab studies

In-situ studies

Modelling