Comparison of observed and predicted air concentrations for 18.6 micron fluorescein particles

From 1967 to 1973, numerous atmospheric dispersion experiments were conducted at Hanford, Washington, by the staff of Battelle Pacific Northwest Laboratories. We compared published data from those experiments to predictions made by the Gaussian plume atmospheric dispersion model for conditions similar to the field releases. The express purpose of the study was to consider the effects of non-zero dry deposition parameters on the accuracy of the model predictions of ground-level normalized air concentrations by comparing these predictions to the published Hanford field observations. Predictions were made consistent with existing dose assessment practices. We conclude that for the conditions tested, the predictive capability of the model was most improved when the deposition velocity parameters (vd) and the gravitational fall velocity (vg) were both set equal to 1.8 cm/s.