“Preliminary Study Of The Nuclear Subterrene”, 1971 ():
[Not an underground rocket; background, and outcome] This report is the product of a series of reviews, analyses, and discussions among a small group of Los Alamos Scientific Laboratory (LASL) staff members during the spring, summer, and fall of 1970. The group consisted of individuals from several Laboratory Divisions, and included a broad range of backgrounds, viewpoints, interests, and professional specialties. As the work of this group continued, a consensus appeared concerning the feasibility of developing a Nuclear Subterrene as a rapid, versatile, economical method of deep earth excavation, tunneling, and shaft-sinking. The concept offered the challenge of a major scientific development and the prospect of an important technological breakthrough. The Nuclear Subterrene was seen to offer potential solutions to many of man’s urgent ecological problems, the means of exploiting many of the earth’s still untapped natural resources, and the exciting possibility of a practical solution to the emerging crisis in the world’s energy supply. Drilling and tunneling by melting the rock was found to be the most promising method of accomplishing these things. It was concluded that the capabilities of high-temperature heat pipes and of small nuclear reactors put the development of a practical rock-melting system—in the form of the Nuclear Subterrene—within the grasp of present technology.
This report presents the outline of a proposed program for development of the Nuclear Subterrene, a summary of the technical background of such a program, several specific program goals, and some speculations concerning applications of the programs products, Several appendixes provide greater detail on some of these subjects.
The rock-melting drill was invented at Los Alamos Scientific Laboratory in 1960. Electrically heated, laboratory-scale drills were subsequently shown to penetrate igneous rocks at usefully high rates, with moderate power consumption. The development of compact nuclear reactors and of heat pipes now makes possible the extension of this technology to much larger melting penetrators, potentially capable of producing holes up to several meters in diameter and several tens of kilometers long or deep.
Development of a rapid, versatile, economical method of boring large, long shafts and tunnels offers solutions to many of man’s most urgent ecological, scientific, raw-materials, and energy-supply problems. A melting method appears to be the most promising and flexible means of producing such holes. It is relatively insensitive to the composition, hardness, structure, and temperature of the rock, and offers the possibilities of producing self-supporting, glass-lined holes in almost any formation and (using a technique called lithofracturing) of eliminating the debris-removal problem by forcing molten rock into cracks created in the bore wall.
Large rock-melting penetrators, called Electric Subterrenes or Nuclear Subterrenes according to the energy source used, are discussed in this report, together with problems anticipated in their development. It is concluded that this development is within the grasp of present technology.
…At the Los Alamos Scientific Laboratory, a device has been developed that bores holes in rocks by progressively melting them instead of chipping, abrading, or spalling them away. The energy requirement for melting rock is relatively high, but it is not prohibitive. (Common igneous rocks melt at about 1200℃ and, in being heated from 20℃ to just above their melting ranges, they absorb about 4300 joules of energy per cubic centimeter. In comparison, the corresponding figures for metallic aluminum are about 660℃ and 2720 J/cm3, and for steel they are about 1500℃ and 8000 J/cm3. The energy requirement for rotary drilling in most igneous rocks is about 2000 to 3000 J/cm3.) Even for a penetrator of very large diameter advancing at a high rate, the melting energy can easily be provided by a compact, high-temperature, nuclear reactor, and LASL has pioneered in the development of such reactors. Energy transfer from the reactor to a melting tool at the rates and densities required would probably be impossible except by means of heat pipes, which have also been highly developed at LASL. Combining the 3 major components—a refractory rock-melting tool, a nuclear reactor, and a system of heat pipes—into a large, rock-melting penetrator called a Nuclear Subterrene would be a natural extension of existing LASL technologies, talents, and scientific interests