Gus NAVAJO) Project 2.65 = Analy of Fall~Out and of Base Surge — M. Morgenthau Oojectives To obtain fallout samples on land and to perform radiophysical and radiochemical measurements on the samples, To prepare dose rate contours of the atoll area from information gathered by this project, other projects, and Rad-safe,. To evaluate the role of the base surge in transport of radioactive material, Description and Experimental Procedures ~ Intermittent fallout collectors (IFC) and gross fallout collectors (GFC) were installed on islands in the Bikini Atoll and on the YAG's and LST in the expected fallout zone. The IFC timing intervals were 1 minute, 5 minutes, or 30 minutes, depending on location of the collector, The equipment was installed prior to the shot and was activated by E.G.&G. Blue Boxes. Samples to be used for early decay measurements were recovered on D-day and the balance of the samples were recovered on Dfl. recovery was made by helicopter. All of the Wire signals were used to activate the base surge detectors as a warm—up period was required before shot time. Some of the stations also incorporated a tape fallout monitor (IFM). On Deday, D1 an aerial survey of residual radiation was made over the respective atolls by helicopter, The measurements were taken by means of a probe on a long cable suspended below the hovering helicopter. The pos=- itions of the probe were determined by comparison with maps and aerial ~ 29 GUA. aX ET. “ S =~ 2 27 !