MC3D is a multi-component thermal-hydraulic 3D software developed by IRSN with collaboration of CEA. It is based on an Eulerian description of the mass, momentum and energy balances of multiphase compressible flows. The major application of MC3D has been the development of two models for Fuel-Coolant Interaction (FCI), one for each step of the interaction, namely premixing and explosion. We firstly present the general architecture of the code (solver), then some numerical specificities of the code. Then we describe some major challenges in FCI physical modeling, and conclude with foreseen improvements of both code general structure and physical modeling.