The Thermal Hydraulic Characteristics Analysis Of Supercritical Carbon Dioxide Pebble Bed Reactor Core

The advantage of supercritical carbon dioxide (S-CO2) is cheap and easy to obtain. As a coolant, S-CO2could improve cycle efficiency therefore it is an ideal option for a small reactor.In this paper, a modular reactor that is directly cooled by S-CO2 is designed.A simple concept design for fuel assembly is preceded by using CFD method. The thermal-hydraulic characteristics are analyzed for different pebble fuel arrangements and different fuel assembly shapes. Then order packed arrangement and cylinder assembly are selected for concept design in next chapter.A design rules is established according to the fuel physical property, then single-channel method is adopted for conceptual design of reactor core, the results obtained could satisfy design requirements. Furthermore the parameters sensitivities for height radial ratio of core and radius of fuel pebble are analyzed, the clad temperature increases with the pebble radial enlarges and the lower of height radial ratio, the position of highest temperature is closer to the outlet.Based on the parameters obtained from last chapter, the porous media non-thermal equilibrium in CFD is adopted to analyze the fuel and coolant thermal-hydraulic properties of individual fuel assembly, then different momentum source model is added to analyze the differences among the three calculation methods. The temperatures got from three models are close and pressure from KTA model is the lowest. Finally, the thermal-hydraulic characteristics under two conditions of the fuel assembly are calculated by CFD andconditions which exceed temperature limitation are obtained.