Natural Convection Heat Transfer Analysis With Different DHX Operation Conditions of Sodium‐Cooled Fast Reactor Using ATHLET Code

Sodium‐cooled fast reactor (SFR) is one of the fourth‐generation nuclear reactor types, which has inherent safety features such as low corrosion and no severe interaction between molten fuel and sodium. However, the severe accident of core melting in SFR needs to be considered. This study uses Analysis of THermal–hydraulics of LEaks and Transients (ATHLET) code to calculate the severe accident of SFR, aiming to promote the development of the system safety analysis code for SFR. This ATHLET code contains the physical parameters of sodium, which can effectively simulate the fluid dynamics and heat transfer performance of sodium. After conducting a sensitivity analysis of the form resistance, it was found that the form resistance coefficient of the primary circuit components could adopt that of steady state in SFR under a severe accident. The impact of three operating conditions of decay heat exchangers (DHXs) in SFR on thermal–hydraulic parameters was discussed. After calculation, it was found that the DHX operation conditions in the cold and hot pools will have an impact on the flow rate and temperature inside the reactor, and the condition of DHX closed in the cold pool is more dangerous.