The influence of bypass flow size and thermal shielding on the overall performance of a small pool-type liquid-metal-cooled reactor are investigated through the use of 3D computational fluid dynamics. 1/4 of the reactor is modeled using a porous media approach for small-detail domains, such as the core and the heat exchangers, and a full conjugate heat transfer approach for all relevant walls. Through the introduction of thermal shielding on the internal wall and an optimal bypass flow based on the ratio of pressure drops over the core and heat exchangers, most of the critical design parameters are in good agreement. The results show that for a well-functioning design the pressure drops of the core and the heat exchanger should be close in value, which can be achieved by selecting the right bypass flow.