Nuclear excavation is the name given to the concept of using large scale nuclear explosion craters for useful projects, such as harbors, canals, and roadway cuts. It is one of the principal applications of the Plowshare Program for industrial, or peaceful, uses of nuclear explosives. Plowshare is sponsored by the U.S. Atomic Energy Commission and is under the technical direction of the Lawrence Radiation Laboratory at Livermore, California. The purpose of this paper is to describe cratering concepts and the present state of nuclear excavation technology. The general nature of the safety hazards associated with nuclear excavation are also discussed.

Under the stimulus of electronic materials development - particularly thin-film studies - and the need for space environmental simulation chambers, a very rapid increase in the availability of industrial-sized vacuum components and systems operable in the ultrahigh vacuum range has taken place in the last three years. It is the purpose of this paper to explore the design considerations of ultrahigh vacuum systems for metallurgical applications.