Development of a Qualified MELCOR Model for IR-360 NPP Using SNAP Software

Development of a qualified thermal-hydraulics and the severe accident model of nuclear power plants (NPPs) is of crucial importance in their design, optimization and safety evaluation. This is also the first step in the safety analysis of the IR-360 NPP for which its design is domestically in process. Without an approved and “qualified" model, deterministic safety analysis (DSA) results are not reliable. In fact, the quality of the developed model should be assessed to ensure the reliability of the analysis results. This study attempts to develop a qualified MELCOR model for the IR-360 nuclear power plant in the SNAP nuclear analysis software. By selecting the appropriate nodalization of the problem and their proper connections, the most important thermo-hydraulics parameters such as pressure and temperature of the fluid, mass flow rate, direction and magnitude of the flow in the primary loop, etc are calculated. A comparison is made between the design parameters and calculated values to obtain the deviation of the model values from the design data. The calculated deviations shown to be below the acceptable limits, specified by the DSA practice including the suggestions of the International Atomic Energy Agency (IAEA). This confirms the qualification of the developed model for the safety analysis of the plant in the next steps.