Numerical study on thermo-hydrodynamics in the reactor internals of SMART

[Display omitted] ► We investigate characteristics on thermo-hydrodynamics in SMART developed by KAERI. ► We calculate velocity, pressure, and temperature under nominal operation. ► We also predict non-uniform temperature when steam generator is broken-down. ► The pressure drop is the highest in the steam generators in the SMART system. ► When SGs connected to 4th floor of FMH are broken, non-uniform temperature appears. The present study investigates distributions of pressure and temperature in the SMART, which is one of the nuclear reactors developed by KAERI. The pressure, the velocity, and the temperature are calculated under nominal operation and non-uniform temperature distributions are predicted in the inlet of core generated by the cases of broken-down steam generator. 3D-numerical simulations using a FVM commercial code is performed to calculate the distributions. Under nominal operation, the pressure drop is the highest in the steam generators as well as the temperature decrement is the highest. Broken-down steam generator yields the unmixed flow. When the steam generator related to the fourth floor in the flow mixing header assembly is broken down, the unmixed flow generates the narrowest hot flow region and the widest temperature range at the inlet of the reactor core.