yt pas ape ao wie. R=: 96 - { le il © shen! . — GABRIEL PROJECT, REOPENED Nicholas M. Smith, Jr. Oak Ridge National Laborato Introduction HO aeot The Gabriel Project has been reopened on the request of Dr. Shields Warren, Director of Biology and Medicine Department of AEC 4 Specifically, the question was asked, “Does recent data on Ranger and i Greenhouse tests enable one to state more definitely the probability of large scale disaster from the dispersion of the debris of a large oe: ii number of atomic bombs?" i 14 a The new data has shown the following: in the first place the size distribution of the particles formed by the radio-active material has been shown to have a peak in the 3/10 micron region by the NRL group. This situation has been suspected by Tracerlab measurments and its investigators conclude that their technique has missed the particles of small size. The implication of this discovery is that the debris on the whole settles out much more slowly than assumed in previous calculations, and that turbulence and precipitation must play a major r@le in the distribution of the bomb debris. -Thus, any calculation based on Stokes Law fall out is of walue only as a frame of reference. The new collection data indicate that the particles are deposited over a much wider area than would result if Stokes Law settling and wind transport were the only means of dispersion. One of the major problems then is to deduce the expected dispersal from the published data. This is usually difficult since the experimenters were more often interested in relative than in absolute measures of activity. There is further evidence concerning the nature of the particles which will have a bearing on this project. The AFOAT-1 group reporting on the Tracerlab findings state that particles from ground burst shots are comprised of essentially glassy materials and are much more difficult to dissolve than particles from air burst shots which are presumably mostly oxides. ee There is some evidence presented by the NRDL investigators that the fe ¥ oh op -1hh *# uswADL 40-326 (KX) < TOE 5S ai a a a CAR SEEED bakeocpie © POE 7 ORGANIZATION & MANAGEMENT - : Df {| DOS ARCHIVES