CHAPTER 7 SUMMARY Jel GENERAL OBSERVATIONS The study of thermonuclear explosions at CASTLE has shown tne fallout problem to be of considerably greater magnitude than predicted. This demonstration of the radiolcgical capabilities of superweapons makes it imperative that scaling relationships for fallout be derived which will acply 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 runge (high yield fission—-low yield thernonuclear). Such a basis may be found in the changes in cloud geometry which are ‘kmown to occur with cnang?s in yield. The increased coverage by fallout appears to be due to the flattening of the source cloud at high yields in contrast to the more nearly spherical cloud shape of the nuclear motel used for tue 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 signif- icance is increased beyond that directly attributable to the increase in yleld over the nuclear rane. (ob) This increese in the area of 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 surerveapons disperse radioactive meterials is to some extert 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 TURTHE? WORK Further study of the interaction of these three factors and com~ paricons 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