Heat-Transfer Analysis of Supercritical-Water- and Superheated-Steam-Cooled Channels of SCWR

Abstract

SuperCritical-Water-cooled Reactors (SCWRs) are being developed as one of the Generation-IV nuclear-reactor concepts. Main objectives of the development are to increase thermal efficiency of a Nuclear Power Plant (NPP) and to decrease capital and operational costs. The first objective can be achieved by introducing nuclear steamreheat inside a reactor and utilizing regenerative feedwater heaters. The second objective can be achieved by designing a steam cycle that closely matches that of the mature supercritical fossil-fuelled power plants.  A detailed steam-cycle layout of a 1200-MW_el SCWR, which was scaled from a singlereheat 660-MW_el modern thermal-power plant is presented in the paper. Heat transfer calculations were made for SuperCritical-Water (SCW) and SuperHeated-Steam (SHS) channels of the proposed reactor concept. In the calculations a uniform and three nonuniform Axial Heat Flux Profiles (AHFPs) were considered for two different fuels (UO₂ and MOX). Bulk-fluid, sheath, and fuel centerline temperatures as well as Heat Transfer Coefficient (HTC) profiles were obtained along fuel channels. The HTC values are within a range of 4.7 – 20 kW/(m² ·K) and 9.7 – 10 kW/(m² ·K) for the SCW and SHS channels respectively.