. to dosage outside has never been determined accurately, Also, leeching by rain and other weathering effects tend te reduce the total dosage received by personnel. The isodose lines are kept in infinity doses as @ point of standard reference. For example, if the infinity dose is divided by five the dose rate at Hel hours is obtained, Also, the fission product concentration within a given isodose line can be deter= mined by a very simple relation as indicated in Paragraph V above, VIII. AN EMPIRICAL METHOD OF FORECASTING THE INTENSITY AND LOCATION OF RADIOACTIVE FALL-OUT ARRAS. + anerrariem sosocumndl 4, The General Method Exployed Intensity of radioactive fall-eut is a functien of bomb yield, fall-out area and the amount and efficiency of the scavenging agent (such as soil, water, snow, etc), Since the particle sise distribatien of the soil within the cloud is not know accurately the area covered by the fall-out cannot be determined quantitatively. Bovever, after analyzing the fall-out frem the TUMBLER/SNAPPER (R) and UPSHOT/KNOTHOLE (R) Test Operations, it is possible to predict just how far out the con= taminating fall-ont will extend frem a given shot. This gives the gensral length of the contaminating area, but imless the density and particle size spectrum within every layer of the cleud is knew accurately there is ne way of determining the width of the contaminating area. Hence an empirical method mst be empleyed based on a study of the fall-out plots show in Figures 1 through 9. ‘There is some indication that the Width of the fall-out area from the lower stem is more or less indepen- inbeel sin nip dent of meteorology, however it appears that the intensity of the fall-out 509,287 UNCLASSIFIED Cine tA