SENSITIVITY AND UNCERTAINTY ANALYSES OF THE ATMOSPHERIC DISPERSION MODEL NPK-PUFF

INTRODUCTION In the early repression phase of a large-scale nuclear accident real-time air dispersion modelling is an integral part of the quantitative risk estimate on which a countermeasure strategy is based. Due to the stochastic and chaotic nature of the atmosphere the calculation of air dispersion is complicated and the accuracy of the spatial and temporal distributions is limited due to uncertainties in the algorithms, model parameters, and atmospheric input. A lack of knowledge of the magnitude and composition of the radioactive release into the environment will further add significantly to the uncertainty in the overall result of the calculation. A clear understanding of uncertainties in the model and the model parameters is of key importance in the decision process. This paper presents a preliminary analysis of uncertainties in the Dutch atmospheric dispersion model, NPK-PUFF. Uncertainties due to the meteorological fields are not all taken into account in this study.