4 research outputs found
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Overview of raise boring and blind shaft drilling with practical applications and particular reference to design limits for accuracy
The current excavation technology of raise boring and blind shaft drilling operations is reviewed. Examples are presented of recent applications of both downhole boring machines and surface-mounted rotary shaft drilling equipment, with comparisons made of operational characteristics, shaft sizes, and accuracy limits of each system. Raise-boring and box-drilling machines are described and current operating practices of these systems are reviewed. The increased interest in slant hole or inclined shaft construction is noted, and techniques and equipment for these special shafts are presented. Practical accuracy limits are discussed for each shaft drilling technique and trade-offs between accuracy, drilling rates, and shaft utilization factors are noted. Finally, the current status of ongoing research and development efforts will be described, and some predictions made regarding worthwhile improvement trends in shaft construction methods
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Application of rock melting to construction of storage holes for nuclear waste
Rock melting technology can provide in-situ glass liners in nuclear waste package emplacement holes to reduce permeability and increase borehole stability. Reduction of permeability would reduce the time and probability of groundwater contacting the waste packages. Increasing the stability of the storage boreholes would enhance the retrievability of the nuclear waste packages. The rock melting hole forming technology has already been tested in volcanic tuff similar to the geology at the proposed nuclear waste repository at Yucca Mountain, Nevada. 6 refs., 5 figs., 2 tabs
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SUBSELENE: a nuclear powered melt tunneling concept for high-speed lunar subsurface transportation tunnels
High-speed lunar surface transportation between manned scientific, commercial, or logistical facilities will require subsurface tunnels because humans must be shielded from Galactic Cosmic Ray and Solar Proton Event irradiations. We present a concept called SUBSELENE in which heat from a nuclear reactor is used to melt rock and form a self-supporting, glass-lined tunnel suitable for Maglev or other high-speed transport modes. We argue that SUBSELENE is an optimal approach to forming transportation tunnels on the Moon because: (1) it uses a high-energy-density, high-efficiency, nuclear power supply; (2) it does not require water or other rare volatiles for upon system muck handling or cooling; (3) it can penetrate through a mechanically varied sequence of rock types without complicated configurational changes; (4) it forms its own support structure as it goes; and (5) it is highly amenable to unmanned, automated operation. We outline the R and D needed to develop a SUBSELENE device and give a cost estimate based on experience with small-scale, field-tested, rock-melting penetrators