Quantification of the uncertainty of physical models integrated into system thermohydraulic codes

International audienceThis paper describes some Uncertainty Quantification (UQ) and propagation performed within the NURESAFE European collaborative project. It especially presents the CEA results in the PREMIUM benchmark, an international benchmark organized by the Committee on the Safety of Nuclear Installations (CSNI, 2013) of the OECD/NEA, devoted to the quantification of the uncertainty of the physical models. It contains a confirmation of the estimation with a propagation of the uncertainties to two experiments including one blindly to check the capacity of the uncertainties to be extrapolated. In addition to the PREMIUM benchmark, other studies are shown, that were carried out to determine the accuracy of different quantifications using different indicators.The difficulties faced during the project are presented and analyzed, and potential high-impact improvements to the method are detected. One of them would consist in developing and assessing an evaluation matrix from SETs and IETs with two parts, one designed for the quantification and the other for the validation. The paper also highlights the need of tools to evaluate the quality of the UQ