Hydrodynamic numerical simulations of a prototypical oxide-metal corium melt representative of fukushima 1-F1 severe accident conditions
Résumé
In the frame of Severe Accident studies, the VULCANO-facility at PLINIUS-platform (CEA - Cadarache) is devoted to the understanding of the interaction of corium with a concrete containment pit (Molten Corium Concrete Interaction-MCCI) [1]. The VULCANO VF-U1 experiment was designed to be closer as possible of the MCCI conditions possibly occurring in the Fukushima F1 reactor considering the coexistence of two dispersed phases (metallic liquid droplets and gaseous bubbles) in a continuous phase (oxide melt liquid).A MCCI industrial code was used to perform predictive calculation of the VF-U1 experiment, being closer as possible of Fukushima 1-F1 MCCI conditions. The results shown that the axial ablation is 8 times higher than the radial one. Then, a multiplicative factor of 8 for the axial heat exchange coefficient must be applied to find the final cavity shape. VULCANO VF-U1 Post-Test Analyses have shown that the metallic phase is preferably close to the vertical concrete walls and at the bottom of the test section whereas a stratification due to density difference between the oxide and the metallic phase is expected (as modeling by the MCCI code). Regarding to the real coupling physical effects in the integral the VULCANO-ICB test and the difficulties for the MCCI code to reproduce experimental behaviors, numerical simulations were conducted. For this purpose, a multiphase Volume Of Fluid (VOF) code at AMU (MADIREL) has been developed . In these calculations, the corium has been modelled numerically under isothermal conditions as a two-dimensional dispersed medium with multiple metal drops and gas bubbles. The results showed a possible hydrodynamic re-localization matching to experimental results.
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