Abstract: The fuel-coolant interaction analysis code COSMETRIC was developed based on MCBA-SIMPLE algorithm. The code was validated against the representative test cases of KROTOS facility. Comparison between the simulation and KROTOS37 experiment results shows that the code is competent to simulate the corium melt fragmentation and drastic evaporation of coolant during the premixing phase. The code also proves to be reliable to predict the amplitude of peak pressure and propagation speed of pressure shock in explosion phase through comparison with the KROTOS21 test results. Sensitivity analysis was carried out to further evaluate the influence of the initial void fraction, the dimensionless time scale in the hydrodynamic fragmentation model and the initial fragment size on the magnitude of pressure shock. It is found that lager initial void fraction leads to lower pressure shock and slower propagation speed, while the increased initial fragment size and dimensionless time scale can reduce pressure magnitude but increase the propagation speed.