Investigation of Thermal-Hydraulic Behavior of Supercritical Water Reactor Using Thorium-Uranium Oxide Fuel (ThO₂-UO₂)

A Super Critical Water-cooled Nuclear Reactor (SCWR) is a Generation IV concept currently being developed worldwide. Unique to this reactor type is the use of light-water coolant above its critical point. The number of SCWR components is reduced since steam separators and dryers are not required. This advantage drives down capital and maintenance costs. Safety is also increased, because a dry out phenomenon does not occur in SCW conditions; SCW remains in a single phase. A computer program by Engineering Equation Solver, (EES) has been produced for inquiry of the fuel, clad and coolant temperatures under supercritical conditions for supercritical water reactor powered by ThO₂-UO₂ mixture as a fuel. In the calculation, uniform axial heat flux and average channel were considered. The bulk fluid, clad and fuel temperatures along fuel length were obtained for supercritical pressures 26, 30 and 40 MPa. Also, the UO₂ percentage added to ThO₂ was varied as, 4% and 10%. It was found that the maximum fuel temperature reached 1917 degree C for a pressure of 26 MPa and 1896 degree C for a pressure of 30 MPa in case of 4% UO₂. However, the maximum temperature of the fuel was 1915 degree C for a pressure of 26 MPa and 1894 degree C for a pressure of 30 MPa in case of 10% UO₂, which is surpasses the industry limit of 1850 degree C. Keywords - (Th, U) O₂ pellets, Thermal conductivity, Thermal hydraulic, Supercritical water reactor