Comparison of the QUENCH-06 experiment between ASYST and RELAP/SCDAPSIM 3.4

•ASYST/SCDAPSIM 3.4 validation and comparison with RELAP/SCDAPSIM 3.4.•Accurate simulation of hydrogen generation according to QUENCH-06 experiment.•Thermalhydraulic simulation on the severe accident field in nuclear reactors. The behavior of nuclear reactors during a severe accident is significantly affected by hydrogen generation. The QUENCH experiments are crucial for understanding the behavior of nuclear reactors during severe accidents, particularly focusing on hydrogen generation and the thermal–hydraulic responses under extreme conditions. Since an accurate prediction of hydrogen generation is crucial for severe accidents simulation codes, especially in the early phase of an accident, this paper presents a comparative analysis of the QUENCH-06 experiment using two prominent simulation codes, ASYST and RELAP/SCDAPSIM 3.4. The paper evaluates the capabilities of both simulation codes to accurately predict the thermohydraulic behavior and hydrogen production during the early phases of a reactor accident. Initial results from both codes are analyzed and discrepancies in hydrogen generation estimations are highlighted. This study aims to validate the improved oxidation models in ASYST/SCDAPSIM code using QUENCH-06 experiment by selecting appropriate oxidation models in ASYST/SCDAPSIM code, given the strong dependency of the dynamics on the hydrogen production rates, and to compare these results with those from RELAP/SCDAPSIM MOD 3.4 code using the same input deck.