Conceptual design of pressure-tube super critical water reactor with inverted geometry

An innovative core design with inverted geometry configuration has been proposed for pressure-tube type supercritical water reactors. The relative positions of fuel and coolant have been inverted and U-Th-Zr-hydride fuel was used. Two-pass water flow scheme has been selected with the assemblies at the periphery of the core having downward flow. Fuel loading pattern and control rod loading pattern have also been proposed in order to achieve more uniform radial power distribution, high coolant outlet temperature and low cladding surface temperature. Three different axial enrichments were used for fuel to reduce the axial power peak which in turn resulted in lower cladding surface temperature. A coupled neutronics and thermal hydraulics analysis was performed for the proposed inverted pressure tube type (IPTT) SCWR and an equilibrium core was analyzed. The results show that, this concept has potential benefits in reducing the clad surface temperature and increasing the life cycle length.