Twenty four site characterization Issues, most of which pertain to the natural system, are presently defined in the Office of Civilian Radioactive Waste Management (OCRWM) Program for the development of a mined geologic disposal system (MGDS) for spent nuclear fuel and other high-level radioactive waste (HLW) at the Yucca Mountain site. Notwithstanding their importance to the successful licensing and timely development of an MGDS, this paper suggests that the overriding natural system question in the OCRWM Program is the attainability of the levels of confidence in MGDS performance required by current licensing regulations. These confidence levels may not be attainable for a natural system unless it is fully integrated with an engineered-barriers system (EBS). Therefore, this paper discusses the potential attainability, or rather unattainability, of existing licensing regulations and outlines an alternative licensing strategy, the As Safe As Reasonably Achievable (ASARA) licensing strategy, that could be employed to optimize the EBS and be compatible with the uncertainties of the natural system.