A Natural Circulation Waste Heat Recovery System for High Temperature Gas-Cooled Reactor Used and/or Spent Fuel Tanks: Part I — Design Considerations and Theoretical Simulation

This paper presents potential application of waste heat recovery (WHR) systems in high-temperature reactors technology. WHR systems have attracted the attention of many researchers over the past two decades, as using waste heat improves the system overall efficiency, notwithstanding the additional cost to upgrade the plant efficiency. WHR systems require specially designed heat recovery equipment, and as such the high-temperature gas-cooled reactor used and/or spent fuel tanks (SFTs) were considered by the way of example. An appropriately scaled system was designed and modelled to demonstrate the functioning of such a system, by the way of a cooling process of the used and/or SFT. Two separate and independent cooling lines, using a natural circulation flow in a particular form of heat pipes called thermosyphon loops were used to ensure that the fuel tank (FT) is cooled when the power conversion unit has to be switched off for maintenance, or if it fails. Assuming a one-dimensional flow model, a quasi-static and incompressible flow of both liquid and vapour, a theoretical model that simulates the heat transfer process in the as-designed WHR system is developed in this paper.