Comparison of an advanced analytical tool with the simmer code to support astrid severe accident mitigation studies

International audienceThe study presented in this paper deals with the assessment, against SIMMER results, of a physical-probabilistic tool dedicated to molten material core discharge. This 0D tool handles heat transfers from molten, possibly boiling, pools to mitigation tube walls, fuel crust evolution, segregation/mixing of fuel/steel pools, radial thermal erosion of mitigation tube wall, and discharge of molten material with axial thermal erosion of the transverse tube, coupled with neutronic evolution of the fuel power. This tool will be briefly described before presenting the comparison with SIMMER-III results, including a space-and energy-dependent neutron transport kinetics model, on several test cases. This tool, which is very low time consuming, will thus enable large sensitivity studies on different physical and design parameters