UNCERTAINTY AND SENSITIVITY ANALYSIS OF A POST-EXPERIMENT CALCULATIONIN THERMAL-HYDRAULICS

This uncertainty and sensitivity analysis accounts for modeling and pa rameter uncertainties originating from the experiment, the mathematica l model, and the numerical solution algorithm. Quantitative uncertaint y statements are derived for code results that are either single-value quantities, like the peak cladding temperature, or continuous-value q uantities, like the cladding temperature at a given position within th e rod bundle. They do not resort to simplifications, like fitted respo nse surfaces, etc., nor to approximations, like fitted distributions, but are obtained directly from the original code results, employing we ll-established concepts and tools from probability calculus and statis tics. These statements account for the combined influence of modeling and parameter uncertainties as well as for the possible impact of the sampling error that is due to the limited number of code runs performe d. Sensitivity measures to single- and continuous-value code results a re presented and the benefit from consulting so-called correlation rat ios, in addition to the more conventional regression-based measures, i s explained and demonstrated.