The United States Army Corps of Engineers Nuclear Cratering Group (NCG) was an organization within the U.S. Army Corps of Engineers (USACE), located at the Lawrence Radiation Laboratory, which was involved in research on the potential uses and effects of nuclear devices for large-scale excavation and quarrying. The group's activities were focused on research for practical applications of nuclear devices, some of which were proposed for the Atomic Energy Commission's (AEC) Project Plowshare program for peaceful nuclear explosions. In particular, the NCG was directed to study excavation techniques for a sea-level canal across the Isthmus of Panama.
The Nuclear Cratering Group was established in 1962. It was reorganized as the Explosive Excavation Research Laboratory under the Waterways Experiment Station in 1971.
The joint USACE/AEC program was established in May 1962 by Presidential directive, with the stated purpose of studying the use of nuclear explosive devices to aid in the construction of harbors, canals, roads, dams, and quarries. In particular, the program was proposed to support research on a new sea-level canal across the Isthmus of Panama or Nicaragua. [1] While the AEC was chiefly responsible for nuclear explosive devices, predictive cratering methods, and execution of actual nuclear explosive tests, the NCG focused on high-explosive testing, nuclear excavation project planning, data compilation on cratering experiments, and engineering studies for the application of nuclear explosives in civil engineering projects. [2] The project's first director was Lieutenant Colonel Ernest Graves Jr. [3]
The NCG's initial role was to conduct experiments with non-nuclear explosives, compiling engineering data that could be extrapolated to the design of projects that would employ nuclear explosives, within the framework of Project Plowshare. [4] [5] The NCG was to plan and execute cratering experiments using conventional high explosives as calibration experiments that would lead to means of extrapolating the performance of nuclear explosives, the development of projects that might employ nuclear explosives, and in conjunction with the AEC, to plan and execute experiments using nuclear explosives. The study group was also tasked with a role in the development of military applications for nuclear excavation. [6]
Studies examined issues surrounding drilling large-diameter boreholes that could accommodate nuclear devices, and methods of creating a series of craters to form linear excavations. Other work focused on radiological studies to establish safe times for re-entry to new nuclear craters. [7]
The Nuclear Cratering Group was reorganized in August 1971 and renamed. The program spent about $175 million, and conducted 22 explosives tests. [8] The U.S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory was its successor activity. [9] [10] Between August 1, 1971 and April 21, 1972, the activity was called the Explosive Excavation Research Office. [11]
There were a number of smaller projects, mainly involving detonations of small explosive charges in various geological conditions.
In support of the NCG's assignment to study potential conventional excavation and nuclear explosive applications for new or expanded canals in the Isthmus of Panama, several projects were examined. [53] [54]
The NCG's final recommendation proposed the use of devices ranging from 100 kt to 3 Mt for a new canal in Panama. Projected costs in 1970 were $2.88 billion using this technique. The report noted that additional testing using nuclear explosives would be necessary before the project could proceed, and that the largest detonations could not be tested at the Nevada Test Site. [55]