CHAPTER 2 THEORY AND BACKGROUND 2.1 THEORY The ultimate objective of studies in fallout phenomenology is the prediction of militery effects from the operational use of nuclear weapons under any given field conditions. The variables include: , 1, 2. Type and yield of weapon Envirorment a. Surface water b&b. Underwater e. Surface land d. Underground ' @ Soil type f. Weather In order to make these predictions it is necessary to have a general theory of the formation and subsequent history of fallout material. Snueh a theory mst encompase several features. First of all there must be a model of fireball dynamics, which determines the mechanism of formation of particles (or drops of water) and the distribution of the particles in the cloud. The mechanism of varticle formation for surface or subsurface detonations is more complicated than a simple vaporization and condensation of earth or water with the incorporation of fission products. There are 2 number of ways in which the activity may be asseciated with the particles. The activity may be deposited on the surfaces; it mey be dispersed uniformly through the perticle volume; or it may be dis- persed in several non-uniform ways through the particle volume. Evidently, the mode of association is dependent upon the mechanism of particle formation and unon the subsequent history of the particles, which may produce changes such as cogrlomeration and lecching by water. The condensation process 1s not thoroughly understood and probably varies with different detonation surfaces, The factors which determine the particle size distribution of the condensate have not been estzblished. In some cases, particularly underground shots, material may b« thrown through the fireball without veporization or even extensive fusion. 14 SECRET — RESTRICTED DATA