Primary System Design Studies for Advanced Direct Cycle Nuclear Gas Turbine Plant

Continuing studies of the Gas Turbine High Temperature Gas Cooled Reactor (GT-HTGR) power plant have been directed toward identification of a plant configuration with improved economic incentives over competing electric power plants. This paper outlines the studies which led to the selection of the primary system for a plant with optimized parameters from the standpoint of minimum power generating cost. As in previously reported designs, an integrated type of plant embodying multiple helium gas turbine loops was selected. The layout of the power conversion loop (PCL) components in the prestressed concrete reactor vessel (PCRV) and the development of the primary system helium gas flow paths are discussed. The studies reported in this paper led to changes in the PCRV geometry which had a significant impact by reduction in the size of the PCRV and attendant cost savings. With orientation and configuration of the major PCL components forming the basis of these studies, some of the preliminary design considerations for the turbomachinery, heat exchangers, thermal barrier and control valves together with maintenance considerations are discussed. The reference plant preliminary design presented is based on a 3000 MW(t) core thermal rating with a reactor outlet (turbine inlet) temperature of 850 C: the overall plant efficiency of the dry-cooled direct cycle nuclear gas turbine is 40 percent.