Reactor cavity cooling system (Rccs) experimental characterization

The development of a new concept for a high temperature gas cooled reactor is strictly correlated to the Reactor Cavity Cooling System (RCCS) design. This is the latest heat sink designed to ensure the cooling down of the vessel and other structural materials during an accident scenario. An experimental facility was built at Texas A&M to quantitatively analyze heat transfer phenomena and the air flow regime inside the reactor cavity. The thermal measurements were performed using 18 thermocouples mounted on the vessel surface, 8 on the external surface of one of the cooling pipes and 24 on a movable rack that captures the axial temperature profile inside the cavity. Flow regime measurements were performed with Particle Tracking Velocimetry techniques (PTV), using a high speed camera and spraying a special dust in the cavity for the tracking. The results demonstrate that the main heat transfer mode inside the cavity is the radiation (about 80%); also, they show the complexity of the flow regime inside the cavity due to natural circulation. The experimental conditions were a vessel surface temperature of about 300 °C heated at fixed power and different flow rates for the cooling pipes.