A Core Design Study of CANDU-SCWR by Three-dimensional Neutronics/Thermal-Hydraulics Coupling

Abstract

A CANDU-SCWR core is designed by using a 3D neutronics/thermal-hydraulic coupling method. In the fuel channel design, a typical 43-element fuel bundle is used, the coolant is supercritical light water, and the moderator is heavy water, the thickness of which is optimized to ensure the negative coolant coefficient during operation. The core has a power of 1220 MWe with a diameter of 4.8m and length of 4.95m, and there are totally 300 fuel channels, each of which consists of 10 fuel bundles. The coolant inlet temperature is set to be 350 degrees C and the operation pressure is 25 MPa. In order to flatten the radial power distribution, the loading pattern of the equilibrium cycle is optimized, and an improved in-out fuel management scheme is used with three batches refueling, burnable poison Dy2O3 is used to flatten the power peaking. The numerical results show that the average power density is 42.75 W/cm3, while the maximum linear element rate(LER) is 575W/cm. The average discharged burnup of the equilibrium is 48.3GWD/tU, and a high average coolant outlet temperature of 625 degrees C is achieved with a maximum cladding surface temperature less than 850 degrees C. Besides, the coolant temperature coefficient is negative throughout the cycle.