Role of borehole plugging in the evaluation of the Waste Isolation Pilot Plant

Research on borehole plugging (BHP) is part of an integrated strategy to develop technology that can assure successful nuclear waste isolation. The application of this strategy to the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico has included an assessment of the role BHP plays in the development of a repository at that site. This paper presents a description of the WIPP site, repository design, and the current research and development program. The status of drill holes - those drilled for petroleum and potash exploration and those drilled for site characterization - within the proposed site boundaries is presented. Sixty-six holes are present on the 7700 hectare (19,000 acre) site, yet only 8 penetrate as deep as the proposed repository location. The assumptions made about shaft and borehole sealing in consequence assessment studies are presented. The results of these studies indicate that borehole seals with effective permeabilities greater than tens of darcies would result in doses to maximally exposed individuals of less than 0.01% of natural background