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U.S. Department of Energy
Office of Scientific and Technical Information

Cost comparison of horizontal and vertical waste emplacement methods for a repository in tuff

Technical Report ·
OSTI ID:60147
Two methods have been proposed for waste emplacement at the Yucca Mountain repository. The first, and reference, method uses vertical holes drilled into the floor of the emplacement drifts. These holes are 25 ft deep and 29 in. in diameter. The alternate method uses horizontal holes, drilled into the emplacement drift wall, that are up to 700 ft long and 33 in. in diameter. This document shows that (1) there are important cost savings resulting from the use of the horizontal emplacement method and (2) these cost advantages exist for horizontal hole lengths as short as 100 ft. The potential, significant savings through the use of horizontal emplacement are obvious from the results of this study. It should be noted that in this study the last waste package in the borehole is placed 32 ft in from the wall of the emplacement drift for all holes (this dimension is referred to as standoff). It is assumed that this 32-ft standoff is satisfactory and that access for maintenance or retrieval can be made possible by blast cooling of emplacement drifts. The major cost differential in horizontal drilling occurs in the transition from 100- to 200-ft holes. This change offers a cost reduction of 29.4%, or $4,285 per container. By comparison, the incremental difference between 200-ft and 700-ft holes is $3,364 per container. The costs shown in this report are the direct operating and capital recovery costs associated with drilling and lining the holes, as well as the appropriate mining costs. The costs of the container, waste transportation to the emplacement hole, and operating and depreciation costs for the surface facility are not included since these costs are fixed regardless of the emplacement method. 6 refs., 8 figs., 18 tabs.
Research Organization:
Sandia National Labs., Albuquerque, NM (United States); Los Alamos Technical Associates, Inc., NM (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
60147
Report Number(s):
SAND--85-1580; ON: DE87010521
Country of Publication:
United States
Language:
English