Development of Dual Cooled Annular Fuel Temperature Analysis Program

To calculate the temperature distribution of dual cooled annular fuel, the DUOS program has been developed. Various thermal hydraulic models to determine the inner channel and outer channel flow distribution were established based on equal pressure drop condition at the top of fuel rod. The effect of gap width change was considered by employing thermal deformation model of pellet and claddings. Heat conduction model in the pellet was solved by finite difference method to consider burnup and power difference according to pellet radius. Pellet temperature model was validated by comparison with calculated temperature profile, which was determined by analytical solution of heat conduction equation under controlled input condition. Accuracy of thermal hydraulic models of DUOS were validated by core sub-channel analysis code MATRA-AF. Coolant bulk temperature of inner/outer channel and pressure drop prediction results of DUOS program show good agreement with that of MATRA-AF. Further models should be added in DUOS program to describe dual cooled annular fuel in-pile behavior, but basic thermal analysis structure has been established successfully