Applicability of Uncertainty Quantification and Sensitivity Analysis for Validation of Fast Reactor Plant Dynamics Analysis Code

This study investigates the applicability of uncertainty quantification (UQ) and sensitivity analysis (SA) methods in the validation process of the analysis results obtained with Super-COPD, a plant dynamic analysis code developed for design study and safety analysis in sodium-cooled fast reactors (SFRs). While the UQ and SA methods have been formalized for light water reactors through OECD/NEA projects (BEMUSE, PREMIUM), their application to SFRs requires consideration of coolant-specific characteristics, particularly natural circulation (NC) for decay heat removal. This research applies forward UQ and the Sobol’ method-based global SA to validate the analysis results of Super-COPD using the FFTF Loss Of Flow WithOut Scram (LOFWOS) test No. 13. Forward UQ, through statistical evaluation, visualizes the uncertainty range of analysis results for net reactivity, outlet temperature of fuel assembly (FA), and hot leg temperature in the primary loop. The validity of analysis results is assessed by confirming that the test results fall within this visualized uncertainty range. SA, employing the Sobol’ method, identifies the dominant input parameters influencing the uncertainty range of the secondary peak outlet temperature of FA. These findings inform the applicability of the Forward UQ and SA employing the Sobol’ method in the validation process for Super-COPD.