Development and uncertainty analysis of the dynamic simulation for HFETR with BMUS framework

In this work, a new approach for uncertainty quantification and sensitivity analysis of research reactor safety is developed, named the BMUS (the Bootstrap and Morris methods for Uncertainty quantification and Sensitivity analysis) framework. The BMUS framework has significant advantages in dealing with small sample sizes, unknown distribution functions, and different dimensions of the input parameters. To verify that the BMUS framework is operational, the uncertainty analysis of High Flux Engineering Test Reactor (HFETR) is conducted under a reactivity insertion hypothetical accident (50 pcm step reactivity perturbation). A Dynamic Analysis of Research Reactor (DARR) simulation tool is established and its accuracy is verified under three hypothetical accidents. During the transient process, the uncertainty quantification results show that the input parameters cause uncertainties in the output parameters, which may lead to power oscillations and sudden temperature changes in the research reactor. The sensitivity analysis results indicate that the strongest correlation is between the core heat transfer coefficient and the secondary outlet temperature. HFETR is moderate sensitive to most of the input parameters, and the highest sensitivity to the heat exchanger heat transfer coefficient.