Environmental radiation safety: source term modification by soil aerosols. Interim report

The goal of this project is to provide information useful in estimating hazards related to the use of a pure refractory oxide of 238Pu as a power source in some of the space vehicles to be launched during the next few years. Although the sources are designed and built to withstand re-entry into the earth's atmosphere, and to impact with the earth's surface without releasing any plutonium, the possibility that such an event might produce aerosols composed of soil and 238PuO2 cannot be absolutely excluded. This report presents the results of our most recent efforts to measure the degree to which the plutonium aerosol source term might be modified in a terrestrial environment. The five experiments described represent our best effort to use the original experimental design to study the change in the size distribution and concentration of a 238PuO2 aerosol due to coagulation with an aerosol of clay or sandy loam soil