NEWCAS: an interactive computer program for particle size analysis.

NEWCAS, a FORTRAN program executable on PDP 11/70, was used to calculate the respirable fraction of aerosols from cascade impactor data. This report describes how NEWCAS works and how to use it. Included is a complete program listing. A novel feature of the program is the method used to display a log-normal probability plot on an ordinary (non-graphics) computer terminal. Calculations are independent of how the stage activity is measured. NEWCAS always assumes a log-normal distribution. 8 figures. (RWR

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 /sup 238/Pu 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 /sup 238/PuO/sub 2/ 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 /sup 238/PuO/sub 2/ aerosol due to coagulation with an aerosol of clay or sandy loam soil

Environmental radiation safety: plutonium/soil interactions for plutonium particles in soil

The goal of this project is to provide information useful in estimating hazards related to resuspension characteristics and subsequent aerodynamic behavior of aerosols from a mixing of soil and /sup 238/PuO/sub 2/. Experiments were carried out to determine whether simple models, used to predict the total activity concentration of resuspended particles, need to be modified to account for changes in the /sup 238/PuO/sub 2/ activity distribution on resuspended particles due to aging of the soil mixture under humid or dry conditions. A literature search revealed that one model, based on the suspension factors, S/sub f/, may be a useful predictor of hazard reduction irrespective of site. Our experiments demonstrated little or no change in the activity of resuspended particles following humid or dry aging of the soil-/sup 238/PuO/sub 2/ mixture. Additional terms for activity distribution changes should not be needed for the simple resuspension hazard model

Environmental radiation safety source term evaluation program

Plutonium-238 is currently used in the form of a pure refractory oxide as a power source on a number of space vehicles that have already been or will be launched during the next few years. Although the sources are designed and built to withstand re-entry into the earth's atmosphere and impact with the earth's surface without releasing any plutonium, the possibility of such an event can never be absolutely excluded. Three separate tasks were undertaken in this study. The interactions between soils and /sup 238/PuO/sub 2/ aerosols which might be created in a space launch about environment were examined. Aging of the plutonium-soil mixture under a humid atmosphere showed a trend toward the slow coagulation of two dilute aerosols. Studies on marine animals were conducted to assess the response of /sup 238/PuO/sub 2/ pellets to conditions found 60 feet below the ocean surface. Ultrafilterability studies measured the solubility of /sup 238/PuO/sub 2/ as a function of time, temperature, suspension concentration and molality of solvent. (ACR