Defining the potential repository siting block Yucca Mountain, Nevada

Siting activities for the potential high-level nuclear waste repository at Yucca Mountain focused on locating a suitable host geologic horizon above the water table. The Topopah Spring Tuff of the Paintbrush Group was identified as the most suitable geologic unit. Sandia National Laboratories (Sandia) identified six areas as potential repository sites. Area known as the Primary Area, is the site of the present characterization and design activities. To support current repository Advanced Conceptual Design, a reevaluation of the Primary Area was conducted by the Yucca Mountain Project's Management and Operating Contractor (M ampersand O). The purpose of the study was to more precisely define the block volume that would be suitable for siting the repository. The Lynx Geoscience Modeling software (Lynx) was selected to be used in this work because of its three-dimensional modeling and visualization capability for geology and underground excavation design. The Lynx model YMP.MO2 was developed in the study. The model includes surfaces that were constructed to represent each of the following limiting criteria: faults, overburden, repository host horizon, and groundwater. The resulting potential repository siting block is the useable volume within these limiting criteria