0018933 rates are present, as is the case for surface or underground shots where the fireball contacts the ground, the local fallout will be large. Local fallout can be expected to decrease as the detonation height increases and become a negligible quantity for an air burst high above the ground. Numerous estimates of local fallout have been prepared at previous Operations, mainly from analyses of radiation intensity data obtained in aerial and surface monitoring surveys. However, the uncertainties in con- verting from dose rate measurements to fission products deposited per unit area are so great that the results cannot be regarded with a great deal of confidence. More reliable values are evidently needed and in planning for Operation HARDTACK, the AEC examined possible ways of obtainingsuch information (Reference 1). After consideration of the difficulties inherent in additional refinement of surface measurement techniques, this approach was abandoned. An alternative program based on further development of existing cloud sampling procedures was formulated (Reference 2) and this culminated in Project 2. 8, A knowledge of fallout partition and how it is influenced by shot environment may contribute to reduction in world-wide fallout at future tests and to a better understanding of the military implications of local fallout. It will also assist in extrapolation to previously untried shot con- SAX BRUNO FRC ditions and yields. 13