Analysis of the accuracy of residual heat removal in gen-IV reactors

Highlights: • Deduction of a reduced model of Navier-Stokes equations utilizing POD-Galerkin. • Uncertainty quantification studied considering inacuracy in dimensionless numbers. • Hundreds of solutions obtained with the surrogate fast model. • Uncertainty determined by mean solution and standard deviation. • Accuracy of standard deviation calculated as a function of the sample size. The assessment of the inaccuracy and sensitivity of simulations of natural convection in pools is of the highest importance for the nuclear industry and concretely for the design of the 4th generation reactors. Therefore, in this article we qualify the uncertainty on the calculation of three dimensional spatio-temporal evolution of Rayleigh-Bénard instability. This assessment is carried out through the creation of a surrogate–fast–model. The model is build utilizing Proper Orthogonal Decomposition and Galerkin projection. The most energetic modes are derived from a high fidelity CFD calculation. The governing equations are henceforth projected into the space generated. Once the model is available, we consider the uncertainties on the dimensionless numbers, Re, Pr, Ra. The expected result and its uncertainty are computed by Monte-Carlo method, calculating hundreds of solutions of the Initial Value Problem with the surrogate model. By this we have verified the applicability of the methodology to this kind of problems and the viability of the approach for uncertainty qualification.