Sensitivity Analyses of Underground Drift Temperature, Stresses, and Safety Factors to Variation in the Rock Mass Properties of Tuff for a Nuclear Waste Repository Located at Yucca Mountain, Nevada

摘要

Preliminary two-dimensional thermal and thermal/mechanical sensitivity analyses of the design of the horizontal emplacement drift were performed for times out to 100 years after waste emplacement. The purpose of the analyses is to provide insight into the relative importance of the thermal and thermal/mechanical properties that impact the stability of the emplacement drift-specifically, heat capacity, conductivity, thermal expansion, insitu thermal gradient, insitu stress, joint cohesion and friction angle, elastic modulus, Poisson's ratio, rock friction angle, rock compressive and tensile strength. This will help prioritize future characterization and analysis activities prior to development. The model input properties were varied over the expected range of their values and the corresponding effect on the temperature, stresses, and safety factors of the rock mass surrounding the drift were recorded. First, the properties were varied individually to determine the independent effects on drift performance. Second, select properties were varied simultaneously to assess joint effects and estimate the probability of undesired drift performance. The results represent a first attempt to estimate the variability of the properties and their effects on the drift. Other sources of variability that can affect drift design are not considered, hence the results are considered preliminary. As site characterization proceeds, the enhanced understanding of property variability will lead to updating the results and conclusions of this report. 15 refs., 2 figs., 8 tabs. (ERA citation 12:030175)