Towards a Comprehensive Interpretation of MCCI 2D tests

摘要

This work has been performed in the frame of the study of molten core concrete interaction (MCCI) during a severe accident of LWR. One of the main issues is the estimation of the time when the reactor cavity may fail due to the erosion of the basemat since it would lead to a bypass of the containment. The calculation of the basemat erosion velocity requires the knowledge of the heat transfer between the corium pool and the concrete. Several experimental programs aim at studying 2D MCCI with real (OECD/NEA-MCCI cooperative project, VULCANO) or simulant materials (ARTEMIS) and have provided fruitful information on this phenomenon. Real material experiments with siliceous concrete, as well as ARTEMIS simulant material tests show a large radial ablation in comparison to the axial ablation. Real material tests with LCS concrete show a more uniform ablation in both axial and radial directions. This difference is shown to be mainly related to the pool thermalhydraulics: a natural convection loop seems to be dominant with siliceous concrete and with simulant material at low superficial gas superficial velocities whereas a bubble agitated pool is dominant with LCS at high superficial gas velocity. The main purpose of this paper is to provide technical support to this interpretation.