Session: 11-02 Severe accident mitigation phenomena

Paper Number: 136230

136230 - Uncertainty and Sensitivity Analysis of Phebus Fpt-1 Experiment Based on Severe Accident Analysis Code Isaa 

Abstract: 

Since the Three Mile Island nuclear accident in 1979, international research into severe accidents has advanced through a combination of experimental studies and numerical simulations. The intricate physical processes and chemical phenomena involved in severe reactor accidents have led to a heavy reliance on empirical parameters in existing severe accident analysis programs, consequently generating significant uncertainties. As a result, there is a growing interest in applying systematic analysis programs combined with uncertainty quantification methods to evaluate the potential consequences of severe accidents, a method that has garnered considerable attention among researchers in the field of severe accident analysis. In 2019, the Europe initiated the MUSA project, an international collaboration focusing on severe accident management and uncertainty. The project centers on a series of severe accident uncertainty analysis studies based on the Phebus FPT1 experiment, which serves as a valuable tool for assessing the effectiveness of severe accident analysis codes in simulating the progression of severe reactor accidents and offers an opportunity to analyze and enhance the physical models within these codes. Previous numerical analysis studies using the integrated severe accident analysis program ISAA for the FPT experiment revealed the necessity for significant estimations, particularly in areas such as core degradation and source term release. This finding underscores the essential nature of conducting uncertainty and sensitivity studies on various parameters that may affect numerical simulation results, utilizing advanced uncertainty analysis methods. In this study, we employed self-developed uncertainty analysis code SAUP to conduct random sampling analysis based on Latin hypercube sampling for various uncertainty parameters, including experimental modeling data and code model parameters. Utilizing the Wilks theory, the study conducted comprehensive uncertainty quantification studies on the thermal-hydraulic results and hydrogen production in the FPT1 experiment, providing a deeper understanding of the uncertainty surrounding numerical simulation results. Furthermore, local sensitivity analysis was carried out using Spearman and Pearson correlation coefficients for hydrogen production, further quantifying the degree of impact of uncertainty parameters on numerical simulations. The research outlined in this paper is crucial in advancing our comprehension of severe reactor accidents. It not only contributes to refining and improving the numerical models within the analysis codes but also plays a significant role in reducing the uncertainty associated with numerical simulations. This work is essential in enhancing safety protocols and emergency response strategies in the event of severe reactor accidents.

Key words:

Severe Accident; ISAA; Phebus FPT1; Wilks' formula; Uncertainty analysis; Sensitivity analysis

Presenting Author: Hao Yang Xi'an jiaotong university

Presenting Author Biography: Yang Hao, a doctoral student, is studying at Xi'an Jiaotong University. Research direction is severe accident analysis

Authors:

Hao Yang Xi'an jiaotong university
Bin Zhang Xi’an Jiaotong University
Jishen Li Xi'an jiaotong university
Pengcheng Gao Xi’an Jiaotong University
Zhiran Zhang Xi'an jiaotong university
Fan Miao School of Nuclear Science and Technology