Since the mid-1990s, the Mining Engineering Department at the University of Nevada, Reno (UNR) has conducted scientific modeling studies to analyze the feasibility and potential benefit of long-term ventilation at the proposed high-level radioactive waste repository at Yucca Mountain (YM), Nevada. One major, overarching scientific interest in the use of ventilation is to reduce temperature and thereby increase predictability and confidence in the repository design. It is of scientific interest to study designs with above- and below-boiling temperatures for comparison, regarding vapor and moisture movement around the emplacement area.; A new, multi-scale, coupled in-rock and in-drift model is used in the dissertation. This model is configured using the MULTIFLUX software with new transport terms which have never been included in previous studies. The model describes heat and vapor or moisture flows along the emplacement drift. It is demonstrated that in an above-boiling repository the drift works as a water/moisture attractor. Sensitivity of the results to the axial transport properties is examined.; Numerical studies are included with a re-arranged waste package sequence to form cold traps over the less critical waste packages. The proposed solution shows fewer waste packages with condensation. As shown in the study, the proposed repository can be kept below boiling for its entire operation time period with long-term ventilation. It is believed that keeping repository temperatures below boiling temperature can reduce uncertainties in performance assessment models, improve safety, and ultimately benefit citizens living downgradient of YM.
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