Project 1: Microbial Consumption of GDF Gases and Implications for Long-Term GDF Performance
Gases will be produced during container corrosion and may overpressurize the GDF, but the ultimate fate of GDF gases remains uncertain. This project will investigate the role of microbiological activity in consuming produced gases and its impacts on GDF components to ensure Engineered Barrier System (EBS) performance over the planned lifespan. Experiments will re-create GDF conditions predicted to be dominant over the one million year safety assessment timeframe, assess how microbial processes are consuming gases, and identify by-products and geochemical reactions from gas consumption. An emphasis of the work will be testing how these by-products and geochemical reactions impact the performance of each GDF component. Computer modelling will be used to predict the implications of experimental results for long-term GDF performance.
Project 2: LHGW GDFs in the Circular Economy: Utilising waste rocks as Engineered Barrier System material
The Engineered Barrier System (EBS) is a key component for GDF safety. The EBS slows the flow of water to limit corrosion, protects the structural integrity of the container, and prevents radionuclides from being released into the environment. The EBS is intended to manage gases produced during container corrosion and waste degradation, through providing pore-space to passively control gas release by storage and to limit pressures. This project explores use of waste rocks from quarries, excavated GDF rocks and re-use of other materials (e.g. concrete waste from NDA sites) for the EBS. Their use as an EBS material would lower the environmental footprint and prevent these materials from filling landfills. We will assess whether waste rock/bentonite mixtures meet criteria for EBS usage, including mechanical strength, fluid/gas permeability, microbial activity for gas consumption and the long-term performance of these re-used materials.