CHAPTER 7 SUMMARY 7.1 GENERAL OBSERVATIONS The study of thermonuclear explosions at CASTLE has shown the fall- out problem to be of considerably greater magnitude than predicted. This demonstration of the radiolegical capabilities of superweapons makes it imperative that scaling relationships for fallout be derived which will apply over the antire range of possible weapon yields. A common basis of development is required if predictions are to be valid for the now undocumented medium yield‘range (high yield fission--low yield thermonuclear). Such a basis nay be found in the changes in cloud geometry which are known to occur with cnang2s in yield. The increased coverage by fallout appears to be due to the flatten- ing of the source cloud at high yields in contrast to the more nearly spherical cloud shape of the nuclear model used for tae predictions. The following general observations may be drawn concerning fallout fron the more diffuse source: (a) The extent of land gamma radiation fields of military significance is increased beyond that directly attributable to the increase in yield over the nuclear range. (b) This increase in the area cf lethality is the result of e more even distribution of fallout over a larger area. Stating it another way, reduction of the extra-lethal or over-kill factor extends the lethal range for fallout. (c) The increased efficiency with which superweapons disperse radioactive materials is to some extent counter-acted by the delay in errival of fallout from the high source cloud and the rapid rate of Gecay which occurs in the interim. 7.2 PLANS FOR TURTHER WORK Further study of the interaction of these three factors and com~ parisons with model data are expected to reveal the part -loud geometry plays in the distribution of fallout. Correlation of data from all GASTLE sources, including the results of water sampling under Project 2.7, will be made using the USNRDL experimental model, Idealized gamma 101