Overview: Waste storages sites are designed to provide safe storage for hundreds if not thousands of years. Given the limited amount of data for system performance, it is important to develop an understanding, using modeling, of how a system's performance will be affected by natural environmental processes. Further, it is crucial to understand the extent of potential for harm to the surrounding population if the storage site's integrity is compromised.
The purpose of this study is to determine the effects, over time, on the environment and any surrounding populations from the performance-either continued site integrity or failure-of Uranium Mill Tailings (UMT) waste storage sites. A review of site performance to date shows that a majority of the storage sites have already experienced some form of failure since the site closure: the primary failures being plant intrusion and erosion. For the purposes of this research, the event of plant intrusion will be considered. Once vegetation has penetrated the cover, many potential failures arise including increased water infiltration, changes in water movement-both into and out of the cover, death of surrounding vegetation due to contamination, etc. Storage cell performance will be evaluated through modeling of various scenarios: repair, no action, and excavation. As limited amounts of data exist about the performance of waste storage sites, performance uncertainty assessment will be used in conjunction with the modeling to demonstrate the potential consequences from the scenarios.
Knowledge of uranium mill tailings waste storage site performance will enable an improved understanding of the relationships that exist between long-term stewardship needs and remediation objectives; and in turn will allow for better post-closure approaches. This information can then be used to assess the performance of other types of waste storage sites.