Natural barriers, including geological formations — salt, argillite, sedimentary or crystalline settings — constitute the most important component of the complex multilayered system that isolates stored waste from the biosphere. Therefore, the design and performance assessment of waste repositories require a thorough knowledge and understanding of host rock behavior. Itasca has pioneered rock engineering research and development in underground nuclear waste isolation for decades worldwide for all rock types (hard rocks, salts, and clays) over geological time periods. For example, in crystalline media, the fracturing state of the rock mass (DFNs) is the main avenue of potential fluid circulation and transport of radionuclides. Modeling evolution of fracturing around the repository rooms (i.e., excavation damage zone) and its effect on rock mass permeability is an essential part of safety assessment. In clayey and saline formations creep behavior is one of the most important factors affecting the stability of the support structures and thus the medium- and long-term performance of the storage facility. Creep strain rates are affected not only by the stress state but also by temperature changes of the rock due to the waste power source slowly decaying with time.
Itasca has been involved in a wide range of activities for waste isolation, including:
Itasca’s work in this field has ranged from time scales of minutes to a million years and from length scales of rock grains and micro-damage to the tectonic, including the impact of water, thermal loading, glaciation, earthquakes, and volcanic dikes. With project work spanning decades, Itasca has been involved with both low-level nuclear waste isolation projects and high-level nuclear waste isolation research and design projects in Australia, Canada, Finland, France, Germany, Great Britain, Spain, Sweden, Switzerland, and several sites throughout the United States.
Waste isolation services include.