The Permeability of Rock Salts

by Nelson Cole

At the University of Texas they found Rock Salts to be more permeable than originally expected. It was known that salt generally blocks fluid at a shallow depth. This feature of salt allows reservoirs to form. However, scientist had contemplated that salt may be permeable at a greater depth. When setting out to conduct experiments University of Texas, professors originally thought that Rock Salt would be used as a hydrocarbon seal for the oil industry. Since salt generally blocks fluid at a shallow depth and allows it to flow at a greater depth. It was quickly confirmed that salt becomes permeable at a greater depth. The real surprise came in that the fluids were sometimes able to flow through the salt at a shallow depth. The findings could have important implications for nuclear waste storage. Previous work on the permeability of salts has focused on the cracks formed by the nuclear waste itself. The findings from the study show that undisturbed rock salt can be permeable as well and it is permeable because of deformation. Continue reading

Geologic Nuclear Waste Storage

by Zoe Dilles

Nuclear energy has enormous potential to alleviate the energy demands of the future, but poses a challenge in its production of nuclear waste. More than 10% of the world’s electricity is generated in nuclear power reactors creating some 10,000 metric tons of radioactive heavy metal waste annually. A sought-after, safe approach to storage is within deep geological repositories but the evolution of these systems over time mechanically, thermally, and hydraulically must be carefully considered. These myriad factors make it quite the engineering feat to accommodate high-level nuclear waste. Not only must the waste be placed in a body of relatively inert rock at depth, particular consideration must be made towards the process of excavation itself. The bore-holes that function as the access points to deep strata with reservoir potential subject the surrounding rock to increased stress which can result in mechanical failure in the form of microcracks, called the excavation damage zone (EDZ). This fracturing can be pinpointed using acoustic emissions that are transmitted through the adjacent intact rock. Continue reading