UNCLASSIFIED ABSTRACT The properties of individual fallout particles produced by nuclear detonations at zero height over shallow sea water are analytically described for the first time. The particles produced during Operation REDWING were slurry masses composed of water, dissolved and crystalline sea salts, and seawater-insoluble solids from the weapon, barge, and ocean floor. Special techniques were used to measure the chloride, water, and insoluble-solids content of individual slurry particles, Autoradiography showed that the activity is primarily associated with the solids. A table of experimental data presents particle size versus time of arrival after detonation as well as measurements of particle density and relative specific activity. Estimates of mass and relative activity of fallout per unit area for certain locations about the shot point are shown. ii UNCLASSIFIED =k EB E£€ KK F 8B FE © L 2 ff ED eh kU UU re <> eee ee ee cm ee ewes a a