‘percent as high as these resulting from a simtlar land surface shot. . (3) Tre long-range areas of fall-cut were assumed to be reasonably represented by the method of vester summation of the winds (as used previously at the NPG and the PPO) augnented by an analysis of the forecast air particle trajecteries. This assumptias was modified following BRAVO ty the development of s formal technique cf fall-out pattern plotting taking inte account the passageccf the particles into different ind systens as the particles drifted avey fras Ground Zero (See pars bd (1) aB8uve and Inel 2 ef Tab D). (&) Since little was imow quantitatively about the long-range variationin radiation intensities wth distanee andarea, certain planning ssrumptions evolved from the mmercas dlecussions during the planning stage of the operation and used as indicated below. Aithough the asemptions were gmmeral and conservative approxisations, they were specifis encugh to be used as operational planmin: fastors with & fair mount of confidence. (a) CLSTLE clouds mere than twenty-four hours old were not asouned te be hasarvcus. Tweshp-Cour hours travel of « CASTLE cloud was assumed to be sppreximately 500 nautéeal sites. ' Teese assunptions proved valid on the oparetion,- amege thab there appeared to be relatively eigificant intensities in savishregions beyond this tine fromthe barge shots. Certainly, it could be assumed thet. the finely dtvided sercech-type clouds from the barge shote would resist fall-cat and therefore persist longer. It ie diffieult to assign. a number to the period of tins involved, although on the basis of cloud: tracking operatiéne for ths barge shots, am’ considering the natural processes of decay ard diffusion, 4t is not believed to be longer than thirty hours. 56