Multi-physics uncertainties propagation in a PWR rod ejection accident modeling - Analysis methodology and first results - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2018

Multi-physics uncertainties propagation in a PWR rod ejection accident modeling - Analysis methodology and first results

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Résumé

In this paper we present a multi-physics neutronics-fuel thermal- thermal hydraulics uncertainty analysis methodology for Rod Ejection Accident (REA) in an academic PWR core design (3x3 fuel assemblies). We define different coupling studies, from simplified separate disciplines cases until complete coupling. For each study the statistical analysis methodology is presented, including Monte Carlo uncertainty propagation, sensitivity analysis for dependent and independent input parameters and the use of surrogate models. Afterwards, preliminary results of a simplified neutronic two group diffusion exercise with adiabatic thermal feedback are presented for static and transient analyses. The calculations were carried out using APOLLO3 code developed by CEA and as input uncertain parameters the two group cross-sections were considered. Static analysis concerns the impact of the method used to render the core critical. Three different methods were studied in order to select one for the transient analysis fission source normalization, boron concentration adjustment and leakage adjustment through the reflector fast group diffusion coefficient. The methods applicability on larger scale cores was investigated together with their effect on uncertainty propagation and sensitivity analysis for quantities related to REA. The results show that the methods have an important influence on the sensitivity analysis. Boron concentration adjustment was selected. Transient analysis concerns two output of interest maximum during REA of the average and hot spot linear power evolution. Uncertainty propagation results show standard deviations of 6% and 7% respectively while sensitivity analysis results using Sobol and Shapley indices show that fast neutron group diffusion coefficient, total, nxfission, self scattering cross-sections, scattering from fast to thermal group and thermal nxfission cross-sections are the most influential. Finally, criticality methods sensitivity on the transient was estimated using Sobol indices and was found to be non negligible.
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Dates et versions

hal-02415310 , version 1 (17-12-2019)

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  • HAL Id : hal-02415310 , version 1

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G. Delipei, J. Garnier, Jc. Le Pallec, B. Normand. Multi-physics uncertainties propagation in a PWR rod ejection accident modeling - Analysis methodology and first results. Multi-physics uncertainties propagation in a PWR rod ejection accident modeling - Analysis methodology and first results, May 2018, Lucca, Italy. ⟨hal-02415310⟩
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