A tightly coupled multi-physics model for MSR system involving the reactor core and the rest of the primary loop has been developed and employed in an in-house developed computer code TANG-MSR.In this paper,the computer code is used to simulate the behavior of the redesigned TMSR for depletion,steady state and transient operation.The presented simulation results demonstrate that the models employed in TANG-MSR can capture major physics phenomena in MSR and the redesigned TMSR has excellent performance of safety and sustainability.