Maintenance Considerations in the Design of the Direct-Cycle Nuclear Gas Turbine Power Plant

In the integrated gas turbine high temperature gas cooled reactor (GT-HTGR) plant, all of the helium turbine power conversion machinery operates on the reactor coolant helium and is installed inside the reactor vessel; therefore, it is important that maintenance aspects be considered during the plant conceptual design phase. The primary objective of the GT-HTGR plant maintenance and inspection plan is to provide facilities, equipment, and component designs of reasonable cost that will yield good plant availability. It is, therefore, a matter of policy to design the reactor and the power conversion system installation, as well as the related maintenance facilities, for practical operation for both planned and unplanned maintenance. All primary system equipment is designed for full plant lifetime, with no limited-life parts, and the influence of maintenance considerations on the design of the major components and the plant configuration is discussed. Turbomachinery change-out is regarded as a planned maintenance activity and the sequence of events, together with the necessary equipment items, for removal and re-installation of helium gas turbine is discussed. The maintenance and repair of components such as the heat exchangers, ducting, and valves, which are designed to last throughout the plant lifetime but could fail due to unforeseen circumstances, are also discussed.