SECRET= nc APPENDIX D FALL-OUT FROM MIKE The experience of detonating devices on low towers and the of the earth in Nevada indicates that there is a sizeable fracti residual radiation deposited on the ground within a few hours aftpr the shot. The current speculaticn as to the cause of this fall-out sand and soil are drawn into the hot fireball if it intersects that earth, and either provides large condensation nuclei which are heavy eno fall, or picks up small radioactive particles as it falls back tojthe earth. It would be expected, as it is indeed observed, that theese f particles are transported by the wind. appropriate Thus, the downwind area to distance§ to the wind speed and time of fall of the particles are contaminafed by residual radioactivity. For the IVY Mike shot the major downwind areas vere large exganses of ocean in which no sampling was made of residual radiation. of fall-out from Mike is therefore wnknown. The There was only one 5 where downwind samples were made, and these were not complete. ectimate the fall-out from Mike, it will be necessary to make s scaling from the meager JANGLE surface shot data. This technique[is fraught with uncertainty because the JANGLE data are poor and there are theories which provide a scaling from 1 KT to 10 Mf. good Neverthelesd, it is considered worthwhile to attemt the extrapolation in order to prdvent a possible accidential contamination and to guide future test p adequate measurements. 1045331 = SECRET UNCLASSIFIED L ANIL