C) PEGRETORESERECTEDDA TA O 0018938 ABSTRACT The primary objective of the project was to estimate the partition of Sr?9 and C5137 between the local and long-range fallout formed by megaton- range nuclear detonations over land and water surfaces. A secondary objective was to determine the spatial distribution of radioactivity (and particles) in the nuclear clouds a few minutes after stabilization. It was planned to achieve these objectives by radiochemical analyses and particle size measurements on the following types of samples: 1. Samples of the particles and radioactive gases present in the upper portions of the clouds to be collected by high flying aircraft. 2. Samples of the particulate matter in the clouds to be collected along nearly vertical flight paths, at several different distances from the cloud axis, by rocket-propelled sampling devices, 3. Samples of the fallout to be collected at an altitude of 1,000 feet by low-flying aircraft, The project participated in a megéton shot (Koa) fired over a coral island, afsepeTryshot (Walnut) fired from a barge in deep water,and a 9-MT shot (Oak) fired over a coral reef in shallow water. The aircraft sampling program was generally successful, and fairly complete sets of both cloud and fallout samples were collected on each shot. The rocket program was unsuccessful due to a variety of equipment malfunctions,