In severe nuclear accidents, corium, a molten mixture of nuclear fuel and structural materials, may interact with the concrete of the reactor containment pit. Understanding the mechanisms involved in such an extreme situation, known as Molten Core-Concrete Interaction (MCCI), is a major challenge, as the concrete containment pit constitutes the last barrier preventing the release of radioactive materials into the environment. While existing integral computationnal approaches are well-predictive in many scenarios (Spindler2006, Sato2023), their macroscopic scale limits the understanding of the MCCI underlying physics. This study aims to address this challenge by developing a mesoscopic-scale model based on the three phase CFD code CIMAC (Boulin2018) in the frame of the ANR IMMOC project. The latter combines both numerical and experimental investigations aimed at helping the understanding of corium/concrete interaction at the mesoscopic level. CIMAC is based on a piece-wise linear interface construction volume of fluide (VOF-PLIC) method (Popinet2009) to track the interfaces between oxidic, metallic, and gas phases. To date, the heat flux at the corium/concrete interface is used to compute a melted mass of concrete which is dissolved into the oxidic phase. The physical properties of the resulting mixture are then computed to map its evolving composition. This approach is illustrated with some test cases that show the feasibility and the relevance of this approach. While the current work is based on a simplified model, future studies will investigate MCCI using an immersed boundary method coupled with the finite element code CAST3M. This integrated framework will employ Mazars’ damage model to simulate concrete degradation. This study represents a very first step towards improving the predictive capabilities of severe accident models, with the ultimate purpose of mitigating severe nuclear accidents.