Uncertainty and Sensitivity Analysis for the Environmental Tritium Code UFOTRI

Computer models are used for predicting the impact of tritium releases. Their reliability, when experimental data are limited, can be judged from benchmark tests and uncertainty analysis. First results of a parameter uncertainty and sensibility analysis are presented for the environmental tritium code UFOTRI. The uncertainty range is shown to be less than one order of magnitude. The bulk of the variance is contributed by leaf area index, minimum stomatal resistance, dry and wet yield and initial soil moisture. Improvements in model assumptions are suggested.