The effect of stratigraphic uncertainty on repository performance

One source of uncertainty in calculating radionuclide releases from a potential radioactive-waste at Yucca Mountain, Nevada, is uncertainty in the unsaturated-zone stratigraphy. Uncertainty stratigraphy results from sparse drillhole data; possible variations in stratigraphy are modeled using the geostatistical method of indicator simulation. One-dimensional stratigraphic columns are generated and used for calculations of groundwater flow and radionuclide transport. There are indications of a dependence of release on hydrogeologic-unit thicknesses, but the resulting variation in release is smaller than variations produced by other sources of uncertainty.