<p>Severe accident conditions in nuclear reactors involve extensive degradation of fuel rods and partial/complete core melting occurring due to multiple failures of safety systems. Such severe accident progression in VVER-1000 reactors is generally categorized into two phases: the in-vessel phase and the ex-vessel phase. As part of the development of analysis tools for severe accident analysis, the computer code ‘CORVES 2.0’ has been developed to model the degradation of the reactor core and other internal components during the in-vessel phase of VVER-1000 reactors. CORVES 2.0 code simulates various physicochemical phenomena during severe accident progression and provides analytical support for the development of severe accident management guidelines (SAMG). During the early phase of accident progression, the code calculates the heat-up of fuel under core-uncovered conditions and captures phenomena such as the formation of a U-Zr-O mixture due to chemical interaction between the clad and the fuel, oxidation of the fuel rods and control rods, and candling observed during metallic meltdown during a severe accident. The developed code models an elliptically-shaped reactor pressure vessel (RPV) lower head (specific feature of VVER) and calculates heat transfer in a stratified corium configuration. CORVES 2.0 code predicts RPV failure and captures the composition of corium outflow, which will be used as input for the core catcher phenomena calculations. These studies are useful for determining severe accident management strategies and are considered for the development of SAMG. CORVES 2.0 code has been thoroughly validated using the results of international severe accident analysis codes. In the present study, the representative scenario of large break loss of coolant accident (LB-LOCA) along with extended station blackout (ESBO) for VVER-1000 reactor has been analyzed using CORVES 2.0 code.</p>