(10) studied the dust at Frenchman's Flats, a dry lake at Nevada Proving Grounds, This dust was that generated by thermal radiation prior to the arrival of the shock wave fron Tumbler/Able shot. Bouton reports that the particle size distribution at NPG is similar to that reported for Dugway Proving Grounds. Vincent Salmon (4) predicted in November 1951 that the throw-out from Jangle underground would be 30,000 tons of which 2000 tons would be below 1 micron diameter based on a laboratory analysis. This indicates that 6.5 percent by weight of the throw-out would be 1 micron or less in diameter. It is assumed that if 1.7 X 1024 particles of approximately 2 micron diameter sre distributed in the atmosphere, the solar radiation will be reduced 10 to 20 per cent. If this is true, then from Rayleigh's relation it follows that only 1/330,000 of 1.7 X 1024 particles of 0.3 micron diameter are seared to reduce solar radiation by the same amount (See equations 1 and 2}, (3) Estimates of Particle Concentration in the Atomic Cloud from Superweapons Exploded on the Surface or Underground At the present time there is practically no information on the concentration of soil in the atomic cloud from surface and sub-surface shots. However, some information exists on this matter with respect to clouds produced by TNT explosiona at Dugway and NPG. This information is contained in Table II and is obtained from references 8 and Sa, According to Reference 8, if the cloud from 320,000 lbs. of TNT exploded 35 ft. underground at Dugway Proving Ground is assumed to be a cylinder which is 3000 ft. high and 2000 ft. in diameter, then total weight of particulate material in the cloud would be 46,000 lbs. provided the soil density is 3 gn/om3, This uses a particle concentration of 2300 particles/cam} sir, hence it applies to the stabilized cloud. If we assume that the true crater dimensions sre 252 ft. in diameter and 77 ft, in depth, then the true volume of the crater is 1.9 X 106 cubic feet if the crater is a paraboloid. The total contents of the crater would then weigh 3.6 X 108 jbs, Hence approximately 0.013% by wt. of the total crater materiel is present in the TNT cloud after it is stabilized. Further calculation shows that the particle size in the cloud is assumed to be from 0.6 micron to 0.7 micron if all particles are spherical, and the total] number of particles in the cloud comea out to be 6x 1018, On the basis of information contained in Tables I and II and using the cube root scaling law and the Jangle cloud data it is possible to obtain an estimate of the number of particles in clouds of superweapons, and the values obtained are given in Tables III and IV. Inspection of Tables III and IV shows that the atomic cloud from a 2 to 3 Megaton Superweapon contains approximately 4 X 1022 soil particles if exploded on the surface and 3 X 1023 particles if exploded underground for particles which are 0.3 gicron or less in diameter. However, it would be unrealistic to assume that all of the 0.3 micron particles in the stabilized atomic cloud would reach the iso- thermal region of the atmosphere. It will be assumed that only 10% of the 0.3 micron particles in the atomiceloud reach the necessary high altitudes, PRCTR EE - wy AMER § ae SS =F ‘e itt soe Fe . ~ C2=22190