CHAPTER 6 SUMMARY 6.1 GENERAL Characterization of cloud and fallout samples from CASTLE has furnished information useful for (1) deducing the mechanism of the formation and subsequent reactions of the debris from nuclear detona-~ tions, (2) assessing the radiological situation in the areas of fallout, (3) synthesizing simulants for use in decontamination tests and (4) in- terpreting data obtained in proof testing atomic warfare countermeasures for ships. 6.2 MECHANISM OF FORMATION AND SUBSSQUENT REACTIONS OF NUCLEAR DETONATION DEBRIS The composition of the debris varied with the weapon type and the location of the shot point. For surface land shots the fallout consisted of irregular solid particles derived from coral with associated bomb products which were usually concentrated at or near the particle surface. The outer layer of the particle was chiefly calcium carbonate; the inner part a mixture of calcium oxide and hydroxide. Apparently the coral grains were taken into the fireball as discrete particles and calcined to the oxide in the high temperature environment. The bomb products collected on the surface of these particles and as they fell through the humid atmosphere they were slaked to the hydroxide and the surface layers reconverted to carbonate. Surface water shots produced fallout with relatively little solid matter. Small particles less than 10 yz in diameter appear to have arri at the earth's surface in the solid or semi-solid state, Liquid drops having a range of size up to several millimeters in diameter were also detected, The mode of formation and subsequent reactions of these fall- out particles is not so well understood as that from the surface land shots. It is apparent that the bomb debris mixed to some extent witb the large amount of sea water and the relatively small quantity of coral that were taken into the fireball, Swaporation of the water probably led to the formation of condensation nuclei derived from the sea water constituents. These small particles then collected the condensed bomb 132 ys. 900131 Detefted