This technical note deals with simulation-based design optimization for the ex-core Transformational Challenge Reactor (TCR). Three-dimensional geometry was created for the TCR ex-core. Computational fluid dynamics (CFD) simulations were performed to optimize forced circulation airflow. The CFD model includes thermofluidic phenomena such as convective, conductive, and radiative heat transfer. The simulation results are presented for three different inlet coolant mass flow rates (2, 4, and 8 kg/s). The observed optimized flow rate for the base configuration was 5 kg/s. The calculated peak temperatures were within the safety limits for all components including the bio-shield (433 K) and the shroud mechanism (473 K).