Radioactive particulates can be found in trace quantities in our environment from a number of sources. These sources include dust aggregation of radon progeny, pollution from the nuclear industry, and contamination from nuclear weapons testing. A uranium mine is a source of aerosols containing uranium decay products which gradually rise through the constant vibrations applied to the earth. The wind also kicks up loose particles from the surface, and even rain droplets can thrust particles upward above vegetation cover to later be airborne.
It is necessary to quantify the fraction resuspended over time to accurately calculate doses of ionizing radiation to individuals from a contamination due to their inhalation in proximity. The method used the Federal Radiological Monitoring and Assessment Center (FRMAC) involves determining a site-specific resuspension factor. The FRMAC manual provides a semi-empirical generic version when one cannot be constructed which fits well with historic data but lacks a physical basis. Further, there is ambiguity over the heteroscedastic trend of sampling over time and the non-zero initial resuspension factor value. I am to address these gaps by gathering evidence to demonstrate valid catenary kinetic transfer models which support an alternative dynamic behavior to resuspension.
I have developed and carried out air sampling experiments to capture resuspended Eu2O3 powder on filters at regular intervals. I then analyzed these samples using neutron activation analysis to quantify the trace amounts of this dispersed powder with high precision. A DD110 neutron generator (Adelphi Technology, Inc.; Fig. 2) to produce Eu-152, whose yield of 841 keV gammas were detected by a High Purity Ge spectroscopic detector. A gold foil was used during each 4-8 hours irradiation to calibrate average neutron flux per run.
The results of the neutron activation analysis were used to evaluate parameters for kinetic transport models for resuspension under still conditions. I have presented the findings of my work to through poster sessions and talks at the Health Physics Society and New England Chapter of the Health Physics Society meetings. I am actively pursuing opportunities to continue and expand on this research. I am interested in developing auxiliary kinetic models of resuspension which consider the enhancement or degradation by individual and combined mechanisms, such as wind, rain, humidity, temperature and (if any) specific radioactivity.