Usage of Possibilistic Methods in Safety Assessment of VVER-1000 Concrete Containments

摘要

A serious problem in processing uncertainty which is often neglected is the different nature of aleatory (i.e., dependent on chance) and epistemic uncertainties. Epistemic uncertainties arise frequently in the tasks of NPP structures safety assessment due to lack of statistical data and possible errors in expert evaluations.Several uncertainty processing methods, including higher-order uncertainty models, are outlined. A possibilistic approach is described in order to allow more relevant processing of uncertainties. This approach is based on fuzzy sets theory and can be more efficient in obtaining uncertain structure responses while keeping computational effort within reasonable limits.A discussion follows how these methods can be compared and applied to assess the structural safety of WWER-1000 type reinforced concrete containment. The article also shows a comparison of example problems' structural response analysis results.