FEB i4 °94 FROM KAMAN SCIENCES CORP 14:14 TO 17822998154 PAGE. @03/825 which are the residue of bomb elements and surface materiais, soil and water, made radioactive by eaccampanying radiation fields. Debris is sucked high into the atmosphere by after winds of the explosion. Where 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 spread and 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 cloud and the more fission fragments are available. The relationship between yield and fali-out is known only qualitatively. 4. PRE~SHOT INFORMATION: The operational aspects of the BRAVO experience were Dianned and conceived in the light of experience gained from previous operations. considered: These factors were a. The basis for forecasting where fallout will go is experience gained from overseas test operations CROSSROADS, SANDSTONE, GREENHOUSE and IVY and to & certain extent from tests at the Nevada Proving Ground. Prior to the firing of BRAVO, only one megaton yield device (IVY-MIKE)-had been detomted. Although conscientious efforts were made to document the fale out from MIKE, only ebout 5% of the total debris could ever be accounted for. The technique used for forecasting fallout pat- terns is to consider the clond as 4 small area source (about a 15 mile radius); then add vestorially forecast winds from the surface to approximately 100,000 feet. The next step is to outline an area on the ground where fallout is expected. This ares is computed by taking into consideration particle size, diffusion into the atmosphere, wind pattern, yield and source radius. Such patterns have peen largely confirmed by experience in Nevada as well as by the meager date available hsre. be The most probable value of the yield from was predicted to be three to five megatons or one half the value of the IVY-LTKE yield. The upper linit of qRafyield Was considered to be of the order of eight megatons. co. The surface radex was plotted, with an insurance factor added, i.6., 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 at various distances was considered to be of the same order of magnitude as for IVY-KTKE. Radiation versus distance lines were transposed to Bikini Atoll,