Studies related to delineating the influence of thermal-buoyancy forces on the thermal-hydraulics of Liquid Metal Fast Breeder Reactor plant components under low-flow thermal transient and steady state conditions have generated unique information which will aid design of these components. Various buoyancy force induced phenomena such as thermal stratification, flow recirculation, stagnation, and channeling are described and the importance to component performance are discussed. The water based studies have been conducted in the Mixing Components Test Facility, a large multi program facility capable of performing generic studies of fluid flow and heat transfer in reactor components under programmed transient and steady state conditions