FEB 14 "94 FROM KAMAN SCIENCES CORP 14:14 TO 1722952154 COGE . 202/226 which are the residue of bamb elements and surface materials, soil and water, made radioactive by accompanying radiation fields. Debris is sucked high into the atmosphere by artter winds of the explosion. ‘here this radioactive debris will fall is a major pre-shot consideration and primarily influences the decision to detonate a nuclear explosion at a certain time. The area over which radioactive debris is spreac anc the intensity of fall-out on the ground are determined by the yield of the explosion as well as by wind pattern since the larger the yield, the more surface materials are sucked up into the ¢loud and the more fission fragments are available. The rela- tionship between yield and fall-out is known only qualitatively. 4. PRE-SHOT INFORMATION: The operational aspects of the BRAVO experience were planned and canceived in the liaht of experience gained from previos operations. considered: a. These factors were The basis for forecasting where fallout will go ig exDerience gained from overseas test operations CROSSROADS, SANDSTONE, GREENHOUSE and IVY and to a certain extent from tests at the Nevade Froving Ground. Prier to the firing of BRAVO, only one megaton yield device (IVY-MIKE) had been detam ted. Although conscientious efforts were made to document the fall- out from MIKE, only about 5% of the total debris could ever de accounted for. The technique used for forecasting fallout pat- terns is to consider the cloud as a small area source (about a 15 mile radius); then add vectorially forecast winds from the surface to approximately 100,000 feet. The next step is to outline an area on the ground where faliout is expected. This area is computed by taking into consideration particle aize, diffusion into the atmosphere, wind pattern, yield and source radius. Such patterns have seen largely confirmed by experience in Nevada as well es by the meager data available hare. b. The most probable value of the yield from QD was predicted to be three to five mogatons or one half tas value of the IVY-LIKE yield. The upper limit of qQyyig@fyiela was considered to be of the order of aight megatons. co. Tha surface radex was plotted, with an insurance factor added, i.a., smaller particles than previous experience indicated necessary were considered. This doubled distances from ground zero where fallout was predicted to occur. ad. The upwind intensity of radiation levels et vari- ous distances was considered to be of the same order of magritude as for IVY-MTKE. Radiation versus distance lines were transposed to Sikini Atoll.