Thermal Efficiency Optimization of a Modular High Temperature Gas-Cooled Reactor Plant by Extraction Steam Distribution

Modular high temperature gas-cooled reactor (MHTGR) is a small modular reactor (SMR) with inherent safety, which is suitable for load following to improve economic competitiveness. The heat regenerative system for MHTGR nuclear power plant, is crucial for the improvement of thermal efficiency. Traditionally, the enthalpy drop distribution method (EDM) is used to study the relationships between thermal efficiency and distribution of extraction steam. However, this strategy is mainly used for off-line design of steam turbine under rated conditions. For load following operation, it is hard to guarantee the extraction steam distribution of EDM due to the highly nonlinear “flowrate-pressure-temperature” coupling of the fluid network. Thus, in this paper, the thermal efficiency is derived analytically based on the steady state model of fluid network. Then the thermal efficiency optimization is cast into a nonlinear programming problem, in which physical constraints can be considered explicitly. The proposed method for extraction steam distribution is of significance for improving the thermal efficiency of normal operation of nuclear power plant.