0018933 reese ones repayseree Rage properties. It was planned to use the radiochemical data from these samples to corroborate the composition of local fallout as determined from the rocket experiments, to in- - vestigate fractionation with particle size, and to compare the composition of local fallout with world wide fallout. It can also be used for determination of device partition if the fallout is shown to be highly depleted in a particular fission product since the enrichment of the debris remaining aloft in this fission product will then be related to the fraction of the debris which has fallen out, in much the same way as has already been described for. interpretation of the enrichnent of a gaseous fission product in the cloud with respect to particulate debris. 1.3.5 Selection of Radionuclides. The radionuclides chosen for determina- ‘tion from the particle samples were those of greatest concern in world-wide fallout, namely sr?° and cst37 plus a sufficient number of others to provide basic data for further investigation of fractionation. sr°? ’ x74, Mo??, cs136, Cot Eu’?6 and U-?’, In the latter category were ‘The members of this group existed in a variety of forms, ranging from gaseous to relatively non-volatile species, during the period of condensation from the fireball. cats was Cetermined in con- junction with elemental analyses for Ca and Na to help in tracing the behavior of the enviromental material which forms the major part of the fallout particles. Analyses for pl, which were tentatively planned originally, were not carried out due to the limited analytical personnel available, the uncertainties of sample collection for this nuclide and the relatively lesser interest in its ultimate late.