Keywords: Hanford Purex scenario, model evaluation, accidental releases, radioactive pollutants, atmospheric dispersion modelling, air pollution, air quality
Dispersion modelling of radioactive pollutants: application of the 'Demokritos' Transport code system for Complex Terrain (DETRACT) to the Hanford Purex scenario
The DETRACT computational system, consisting of a meteorological processor and a Lagrangian particles atmospheric dispersion model, is applied to the 'Hanford Purex Scenario' – an accidental 3 1/2 days of lasting release of radioactive 131I from the stack of the Hanford (USA) Purex Chemical Separations Plant (2–5 September 1963) – for evaluation purposes. During the release, the source intensity and the wind direction varied. The variables used for the model evaluation were daily-averaged and time-integrated concentrations in air, according to the available observations. Graphical and statistical means (factor-of-2, of-5 and of-10) were applied for the evaluation. The obtained results (18%, 45%, and 53% for the daily concentrations and 38%, 63%, and 81% for the time-integrated concentrations, respectively) are discussed in view of the computational system suitability for use in complex situations of accidental atmospheric releases of hazardous contaminants, including radioactive pollutants, and its sensitivity to the spatial density of the meteorological observations.