4 ‘ Be. Conversion of counting rates to microcuries, Although © the prirery interest of this project was in relative activities, advantage was taxen of these standards to calculate absolute activities. Since the neutron flux, weight of 3235, and fisston . yields 17/ were known, it was possible to obtain for each fission product of interest a ratig2 ef pe to c/m for each counter, fission cross section of U°39 was taken as 575 barns. The Except in the case of very long lived nuclides, counting rates were read from smoothed decay curves, These values were corrected to sero time, 100 per cent, chemical yield, zero added . absorber, and standard tube and shelf, The corrections to zero added absorber were based absorption curves measured in these Lahoratories. Data for "Be Mo77 were corrected for self-absorption and self-scattersng. The seiko: introduced by neglecting these corrections for S 0, can Ce: are discussed in Section 5,1, . 9, Zr? The aluminum cards on which the samples were mounted provided infinite back~-scattering, For. the gross activity measurements small aliquots of the dissolved samples were evaporated in glass counting cups, The counting technique was sinilar to that for the individual nuclides except that the various corrections were not attempted, . Gross decay measurements from 110 to 200 days were performed on aliquots of the dissolved size fractions evaporated in small glass planchets, The counting was done with thin mica end window GM counters, The physical geometry of the system was defined by a hole in a 3/8 inch brass plate which minimized the contribution of side scattering, The total absorption between the sample and the sensitive volume of the counter corresponded to about 6 mg/cm®, The counting rates were corrected only for coincidence loss, Since absdrption and scattering effecta are more or less sigificant depending uponthe beta energies, the slopes of the gross decay curves cannot be directly correlated with the radiochemical composition unless these pertinent corrections aa ma a have been made, 3.4.5 Quantitative Analysis As a result of the tremendous heat generated by the detonations, large volumes of sea water were evaporated and sodium chloride was incorporated inte the fireball, Bunney and Ballou 13/ concluded from a thermodynamic study that chloride ion would be the predominant form of chlorine in the fallout, They reasoned that the strong electronegativity of chlorine would cause it te react at high temperature with alkali and some other metals to form chlorides, They do not consider chlorates and perchlorates possible at high tenperature, For further information with regard to formation of the particles in the fireball and their subsequent history, the chloride ion concentra tion was determined by the Volhard method 14/ in each size-fraction of the fallout, The calcium ton concentration for each size-fraction of the fallout was also cetermined by the method described by Treadwell and Hall is/ . This procedrre involves the quantitative precipitation of 26 SECRET —- RESTRICTED DATA i € 4