Repository drilled hole methods study. Final report
Two methods of canister emplacement, vertical and horizontal, are being considered for possible use in underground nuclear waste repositories. One emplacement method involves drilling 30-ft-deep vertical holes in the floor of a tunnel, and the other involves drilling 600-ft-long horizontal holes in the rib of the tunnel. This report analyzes the technology available, various drilling methods and equipment, and establishes cost data for both methods. The method recommended for vertical, blind holes is a two-step process - a pilot drill followed by a blind reaming bit. The pilot hole permits the shaft to be drilled by hydraulic thrust, rather than by using weights, and thus enhances mobility. Cuttings from the reaming step are removed by vacuum. This is mobile, efficient, and avoids contamination of the repository by drilling fluids. The horizontal holes are drilled with a modified blind boxhole drill, featuring an in-hole drive and a nonrotating drill string. Close drilling tolerances can be maintained because the unit is continuously steered. A laser guidance system monitors true position. Cuttings removal by vacuum is recommended. Drilling costs per canister emplaced in the horizontal mode are only one-fourth as much as drillig costs per canister in the vertical mode. 14 figures.
- Research Organization:
- Robbins Co., Kent, WA (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 59536
- Report Number(s):
- SAND-83-7085; ON: DE84016393
- Resource Relation:
- Other Information: PBD: Jul 1984
- Country of Publication:
- United States
- Language:
- English
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