Site characterization includes borings, surface excavations, excavation of exploratory shafts, limited subsurface lateral excavations and borings, and in situ testing at depth needed to determine the suitability of the site for a geologic repository, but does not include preliminary borings and geophysical testing needed to decide whether site characterization should be undertaken. Unanticipated processes and events means those processes and events affecting the geologic setting that are judged not to be reasonably likely to occur during the period the intended performance objective must be achieved, but which are nevertheless sufficiently credible to warrant consideration. Unanticipated processes and events may be either natural processes or events or processes and events initiated by human activities other than those activities licensed under this part. Underground facility means the underground structure, including openings and backfill materials, but excluding shafts, boreholes, and their seals. Unrestricted area means an area, access to which is neither limited nor controlled by the licensee.
Unsaturated zone means the zone between the land surface and the regional water table.
Generally, fluid pressure in this zone is less than atmospheric pressure, and some of the voids may contain air or other gases at atmospheric pressure. Beneath flooded areas or in perched water bodies the fluid pressure locally may be greater than atmospheric. Waste form means the radioactive waste materials and any encapsulating or stabilizing matrix. Waste package means the waste form and any containers, shielding, packing and other absorbent materials immediately surrounding an individual waste container. Water table means that surface in a groundwater body at which the water pressure is atmospheric.