Using Atmosphere-Forest Measurements to Examine the Potential for Plume Depletion and Reduction of Radiological Dose by Forests

The potential for radiological releases from nuclear processing facilities such as those at the Savannah River Site pose a risk for exposed downwind individuals. Of particular interest are releases of tritium oxide which behaves much like water in the atmosphere and can be absorbed into local vegetation. While the characteristics of the forest at the Savannah River Site are considered in Gaussian plume modeling, the potential for uptake of tritium oxide and trapping of a portion of an airborne plume by the forest and the subsequent reduction in radiological dose to downwind individuals is not well understood. The current practice of modeling uses the conservative practice of assuming no uptake of tritium oxide which is unrealistic. We have used a combination of a Gaussian Plume Model and a 2-D Advection-Diffusion model to assess the atmospheric concentrations above and within the forest environment resulting from a hypothetical plume release over a forest under a range of stability and atmospheric conditions. Results will be presented assessing the potential for a plume to become temporarily trapped in the forest environment and how this affects downwind predictions of radiological dose.