APPENDIX 13.-PROJECT BUGGY-ANNOUNCEMENTS U.S. ATOMIC ENERGY COMMISSION NEVADA OPERATIONS OFFICE The Atomic Energy Commission plans to conduct an experiment at its Nevada Test Site tomorrow as part of its Plowshare program in which excavation technology is being developed for peaceful purposes. The experiment-called Project Buggy-is part of a continuing program to develop nuclear excavation technology and will involve the simultaneous detonation of five low-yield (about one kiloton) nuclear explosives. The experiment is expected to produce a ditch-like crater about 70 feet deep, 200 feet wide, and 820 feet long through level terrain in dry rock. Previous experiments, using conventional explosives, have demonstrated that the simultaneous detonation of explosives appropriately spaced in a line and buried at carefully chosen depths will produce a ditch-like crater. If this effect can be duplicated with nuclear explosions, it will be a major step in developing, for the benefit of all nations, an economic and practical nuclear excavation technology for use in digging harbors, canals, and railroad and highway passes through mountains. Buggy will release only a small amount of radioactivity. Most of it will be trapped underground or in the earth and rock debris deposited near the crater. The experiment has been designed so that almost all of the little remaining radioactivity will be deposited within the controlled area. I. Introduction BACKGROUND INFORMATION ON PROJECT BUGGY The Atomic Energy Commission, in its Plowshare program, is studying and developing a technology for using nuclear explosives for peaceful purposes. With a tremendous amount of energy in a relatively small package, nuclear explosives may make feasible projects which otherwise would be uneconomic or technically impractical. Since the Plowshare program was established in 1957, AEC has conducted 20 nuclear field experiments and extensive laboratory research and development, and has derived data from numerous nuclear tests conducted for other purposes. From this work an understanding of the basic phenomena of underground nuclear explosions is evolving. When a nuclear explosion occurs very deep underground in hard rock it produces a large amount of broken rock, but does not break the surface of the ground. When the explosion occurs at a lesser depth, a crater is formed in the surface. The AEC in its Plowshare program is currently studying in more detail the basic effects of explosions in a variety of geologic media and under a variety of conditions, and how these effects can be put to use. The ability of an underground nuclear explosion, at the proper depth, to break and move-in one step-vast amounts of earth and rock offers potential for undertaking large earth-moving projects. Studies thus far indicate that nuclear explosives might be used for large-scale projects such as constructing harbors. water reservoirs, ship canals, and highway and railroad passes through mour tain ranges. One potential application the use of nuclear explosives to dig a sea-level canal, is being investigated in detail as part of a special study by the Atlantic-Pacific Interoceanic Canal Study Commission. Under Public Law 88-609, the Canal Study Commission will recommend the best route, method of construction, and estimated cost for a sea-level canal. Recognizing the potential of a safe and economic excavation technology using nuclear explosives, the AEC has been actively engaged for several years in developing such a technology. To date, in addition to several hundred cratering experiments with chemical explosives, several nuclear cratering experiments in a variety of media and with energies up to 100 kilotons have been conducted. However, considerable experimental data are still needed before the technology is fully developed. Buggy is the next step in this development program. 98-179 0-68- -22 II. Project Buggy The AEC plans to conduct Project Buggy at its Nevada Test Site near Las Vegas. The five simultaneous explosions are expected to release energy equivalent to about 5,000 tons (five kilotons) of TNT. The energy released by each explosion will be equivalent to about 1,000 tons of TNT (one kiloton). The five explosives will be placed and detonated at a depth of 135 feet underground and spaced 150 feet apart. Each explosive will be put in a 48-inch diameter, uncased hole. The holes will be stemmed, or sealed, with dense sand and concrete plugs set into the surrounding rock. This method of sealing emplacement holes has been successfully used in previous cratering experiments, both nuclear and chemical. Previous experiments, using conventional explosives, have demonstrated that the stimultaneous detonation of explosives appropriately spaced in a line and placed at the proper depth will produce a ditch-like crater. Buggy, using nuclear explosives, is designed to duplicate this effect. If it does, it will be a major step in developing, for the benefit of all nations, an economic and practical nuclear excavation technology for use in digging harbors, canals, and railroad and highway passes through mountains. Buggy, like previous underground cratering explosions, will release only a small amount of radioactivity. Most of it will be trapped underground or in the earth and rock debris deposited near the crater. The experiment has been so designed that almost all the little remaining radioactivity will be deposited within the controlled area. The plan for Buggy includes awaiting very precise weather conditions to assure public health and safety. These weather conditions dictate the exact date of the experiment. These and other precautions will assist the United States in meeting its obligations under the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water. III. Previous Experiments The first Plowshare ditching experiments were performed as part of Project Toboggan conducted at the Nevada Test Site in late 1959 and continued during the late spring of 1960. The series involved 122 detonations of chemical high explosives emplaced in playa (a combination of silt and clay). They were de signed to study ditching characteristics of conventional high explosives in preparation for nuclear row-charge experiments. A series of row-charge experiments, called Project Rowboat, took place at the Nevada Test Site in June 1961. The series consisted of eight separate experiments, each involving the detonation of four 278-pound chemical high explosive charges in desert alluvium. The purpose was to study the effects of depth of burial and explosive-charge separation on crater dimensions. Project Dugout, conducted at the Nevada Test Site in June 1964, involved the simultaneous detonation of five 20-ton charges of chemical high explosives in basalt. Dugout was designed to study fundamental processes involved in rowcharge cratering in dense, hard rock. In addition, the Nuclear Cratering Group of the U.S. Corps of Engineers has conducted several row-charge experiments using chemical explosives in support of the Plowshare excavation program. Pre-Buggy I, conducted at the Nevada Test Site in November 1962 and February 1963, consisted of six single-charge explosions and four multiple explosions of five charges each. Pre-Buggy II also was conducted at the Nevada Test Site during the summer of 1963. Five rows of five 1,000-pound chemical high explosive charges and one row of 13 1,000-pound explosives were detonated in alluvium. The purpose, both of Pre-Buggy I and Pre-Buggy II, was to study row-charge phenomenology and effects in preparation for nuclear row-charge experiments. The most recent chemical explosive row-charge experiment was called PreGondola II and took place adjacent to the Fort Peck Reservoir in Valley County, Montana on June 28, 1967. It was a joint experiment of the AEC and the Army Corps of Engineers to further develop the technology, costs, and other factors involved in nuclear excavation. It was designed to investigate row-charge cratering characteristics and engineering properties of a wet clay-shale medium and to test the ability to connect a row charge detonation to an existing single-charge crater. Two 40-ton and three 20-ton chemical high explosive charges were detonated simultaneously, resulting in a crater 280 feet wide and 640 feet long. The excavation connected successfully with the existing crater. In addition to ditching experiments utilizing chemical explosives, four nuclear and several hundred chemical point charge experiments have been conducted as part of the Plowshare program. Project Sedan, conducted in July 1962, was the first major nuclear excavation experiment. It released 100 kilotons of energy and was carried out in desert alluvium. Three other Plowshare nuclear excavation experiments have been conducted at the Nevada Test Site: Sulky in December 1964; Palanquin in April 1965; and Cabriolet in January 1968. U.S. ATOMIC ENERGY COMMISSION, WASHINGTON, D.C., MARCH 12, 1968 NOTE TO EDITORS AND CORRESPONDENTS The following announcement was dictated to the wire services at Las Vegas, Nevada, at 3 p.m. EST, Tuesday, March 12, 1968: "The Atomic Energy Commission conducted a low-yield nuclear row-charge experiment at its Nevada Test Site on March 12, 1968. The experiment was part of the Commission's Plowshare program to develop peaceful uses of nuclear explosions. "The experiment consisted of the simultaneous detonation of a row of five nuclear explosives each having a yield of about one kiloton (equivalent to 1000 tons of TNT). The explosives were buried at a depth of 135 feet and spaced 150 feet apart. The experiment produced a ditch about 80 feet deep, about 300 feet wide, and about 900 feet long. "The experiment, called Project Buggy, was part of the Commission's program to develop nuclear excavation technology. It will provide information about ditching effects in level terrain in hard rock." APPENDIX 14 Int. J. Rock Mech. Min. Sci. Vol. 4, pp. 1-22. Pergamon Press Ltd. 1967. Printed in Great Britain. COMPUTER CALCULATIONS OF EXPLOSION-PRODUCED CRATERS* J. T. CHERRY Lawrence Radiation Laboratory, University of California, Livermore, California (Received 12 September 1966) Abstract-This paper presents a technique that seems to calculate adequately, from first The technique features a standard, numerical approach to high-intensity, stress-wave A preshot testing programme is presented which obtains the necessary material properties from logging tests in the medium and from laboratory tests of selected rock samples. In situ properties to be determined by field logging are density and elastic velocity (compressional and shear velocity). Sample properties to be determined by laboratory tests are hydrostatic compressibility (to at least 40 kb), triaxial data, tensile strength, Hugoniot elastic limit, and high-pressure Hugoniot data for the rock near the point of detonation (nuclear only). Calculations are presented for Project Hardhat (5 kt, nuclear in granite), Project Scooter (0-45 kt, high-explosive in alluvium), Project Danny Boy (0-42 kt, nuclear in basalt), Project Sulky (0-09 kt, nuclear in basalt), and three parameter studies featuring rhyolite equationsof-state. The Danny Boy calculation confirmed spalling to be the predominant, nuclear cratering mechanism in hard, dry rock. This observation permitted the construction of a free-fall, throw-out model which gave a reasonable estimate of crater radius and ejecta boundary. The rhyolite parameter studies give some insight into the importance of medium properties in determining crater geometry. Further effort in this area is required; however, the agreement between the above calculations and the field experiments indicates that the technique is capable of resolving this issue. 1. INTRODUCTION A FUNDAMENTAL goal of the Plowshare Programme is to predict crater dimensions when an explosive of known yield is buried at a given depth in a given medium. This paper presents results from a numerical technique that attempts to calculate crater development from first principles. We hope eventually to develop this technique to a point where crater dimensions are easily obtained from the calculation of mound growth and cavity growth. We regard the cratering process as a wave propagation phenomenon, necessitating an understanding of material properties from a few megabars in pressure down to the elastic level. The first part of this paper describes a general, numerical approach to stress-wave propagation. In the second part, we discuss the material properties needed to define the stress field that occurs when a stress wave propagates through a brittle medium. The third part of the paper presents the numerical solutions for Project Hardhat (5 kt, nuclear in granite), Project Scooter (0-45 kt, high-explosive in alluvium) Project Danny Boy (0-42 kt, nuclear in basalt), Project Sulky (0-09 kt, nuclear in basalt), and three parameter studies featuring rhyolite equations-of-state. * Work performed under the auspices of the U.S. Atomic Energy Commission. 2. NUMERICAL SIMULATION OF STRESS-WAVE PROPAGATION SOC and TENSOR (MAENCHEN and SACK [1]; CHERRY and HURDLOW [2]) are Lagrangian finite-difference approximations to the momentum equations that describe the behaviour of a medium subjected to a stress tensor in one (soc) and two (TENSOR) space dimensions. These two codes give a numerical description of the propagation of a stress wave of arbitrary amplitude through a medium. A wave is a time-dependent process that transfers energy from point to point in a medium. A wave propagates through a medium due to a feedback loop that exists between the various physical properties of the medium that are changed due to the energy deposition. A schematic of stress-wave propagation is presented as Fig. 1. The equation of motion provides a functional relation between the applied stress field and the resulting acceleration of each point in the medium. Accelerations, when allowed to act over a small time increment A,, produce new velocities; velocities produce displacements, displacements produce strains, and strains produce a new stress field. Time is incremented by A, and the cycle is repeated. The time increment (A,) is determined by an independent stability condition which requires the increment to be smaller than the time necessary for a compressional wave to travel across the smallest zone. There are two areas that need further discussion in the above loop: (1) the manner in which the stress field produces accelerations, and (2) the manner in which the strain field is coupled to the stress field through the equation-of-state of the medium. We limit the discussion, here, to spherical symmetry, and we attempt to interpret the equation of motion and medium behaviour in a general way. If this is possible, then an extension to a less restrictive geometry should not be too difficult. The fundamental equations of continuum mechanics (conservation of mass, linear momentum, and angular momentum) combine to produce the following equation of motion for soc (spherical symmetry): |