"The study of the toxicity of Ra and MsTh(Ra/sup 228/) in humans was continued. Several Thorotrast cases were also examined. Physical and clinical studies were made on 151 persons. In all cases possible gamma ray measurements were made of Ra and MsTh decay products retained in the body, alpha -ray measurements of Rn and Rn/sup 220/ in breath, a complete medical history was taken, a complete x-ray examination was made of the skeleton, and urinalysis, hematological, and blood chemistry studies were made."

Over the past 13 years a considerable body of data on explosive cratering has been developed for application to nuclear excavation projects. These data were obtained from some ten cratering programs using chemical explosives (TNT or nitromethane) and seven nuclear cratering detonations. The types of media studied have ranged from marine muck to hard, dry basalt, although most effort has been devoted to craters in NTS desert alluvium and basalt. Considerable effort has also been devoted to the study with chemical explosives of the use of linear explosives and rows of point charges. This paper is intended to be a summary of these data and a statement of the understanding which has been developed from them.

The effects of explosion-induced ground motion must be evaluated in planning and executing any nuclear excavation project. For some projects ground use intensity may dictate the use of less-than-optimum yields to minimize damaging effects. In remote areas, weighing the alternatives of outright purchase of some property or use of smaller yields may be required. The cost of indemnifying owners against damage must be considered in any case. Discussions of the effects of ground motion on three broad types of facilities - engineered structures, residential buildings, and equipment required for the support of nuclear excavation operations - are presented. A method of predicting the response of single- and multi-storied buildings, the response spectrum technique, is discussed, with emphasis on the application of explosion-induced spectra.