INTRODUCTION: STATEMENT OF THE PROBLEM This paper deals with a program currently under way at Sandia National Laboratories (SNL) to characterize source term aerosols from radioactive materia 1 s exposed to extraordinary environments and to produce improved estimates of environmental and human health consequences. The extreme environments of interest here have been divided into two categories-those related to sabotage (or intentional) acts and those related to extra severe accidents. Major efforts in this program to date have concentrated on the intentional act activity in which the objective is to develop an experimental data base characterizing the release of radioactive material resulti ng from the sabotage of a spent fuel transport. This experimental data base would be the primary input to an analysis of the human health and economic consequences for these types of environments. The origin of the program can be traced back to 1975 when the U. S. Department of Energy (DOE) sponsored a study at SNL to determine the ability of several generic high energy devices to disrupt a large truck spent fuel shipping container. The results of this study indicated that it was indeed possible for certain high energy devices to breach a large spent fuel cask.