Document Type

Technical Report

Publication Date



The U.S. Nuclear Waste Technical Review Board [Cohon et al. 1998] evaluated the technical and scientific validity of activities undertaken by the Secretary of Energy to characterize Yucca Mountain, Nevada, for its suitability as an underground repository in which to store high-level radioactive waste and spent nuclear fuel. In the report, the Board pinpointed that the study on groundwater flow and radionuclide transport in the saturated and unsaturated zones below Yucca Mountain should, over the next several years, focus on reducing prediction uncertainty. In its 2002, the Board repeated this concern by stating, “… hydrogeologic processes that affect radionuclide transport below the proposed repository in the unsaturated and saturated zones remain poorly understood.” However, above the saturated zone, the unsaturated zone (UZ), the area in which the repository would be located, acts as a critical natural barrier by delaying the arrival of radionuclides at the saturated zone and by reducing radionuclide concentrations in groundwater through dispersion and dilution. Before any analysis of saturated zone behavior becomes relevant, quantitative prediction of radionuclide transport in the unsaturated zone becomes critical for performance assessment and design of the repository of the Yucca Mountain Project (YMP).


Groundwater; Hydrogeology; Nevada – Yucca Mountain; Radioactive waste repositories; Radioisotopes – Migration


Geology | Hydrology | Radiochemistry




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Report Document Identifier: SIP-DRI-038

Task ORD-FY04-016