A Natural Circulation Waste Heat Recovery System for High Temperature Gas-Cooled Reactor Used and/or Spent Fuel Tanks: Part II — Theoretical and Experimental Validation

Since the beginning of the twenty-first century, energy conservation has become a major feature of interest in most industrialised countries. The economics of saving energy versus wasting it has driven industrial activists to pay more attention to energy conservation. The implementation of energy conservation requires that all the possibilities of counteracting any potential loss of energy must be considered. This includes reducing heat losses from furnaces, thermal insulation, repair of steam leaks in power plants, heat loss from nuclear reactors, and all other practices that may be implemented rapidly and, preferably at low cost. Once this is achieved, further strategies have to be developed to stabilise short-term energy conservation in systems by implementing permanent solutions. Permanent energy conservation solutions are more expensive, but result in energy benefits over many years. These permanent solutions are referred to as Waste heat recovery systems (WHRSs). This paper presents potential application of WHRSs in high-temperature reactors technology. WHRSs have attracted the attention of many researchers over the past two decades, as using waste heat improves the system overall efficiency, notwithstanding the cost of extra plant. WHRSs require specially designed heat recovery equipment, and as such the used and/or spent HTR fuel tanks were considered by the way of example. An appropriately scaled system was designed, constructed and tested to demonstrate the functioning of such a cooling system first and validated the theoretical model that simulates the heat transfer process in the as-designed WHRS. It is a one-dimensional flow model assuming quasi-static and incompressible liquid and vapour flow its mathematical simulations as developed in Part I (Senda and Dobson, 2013). Two separate and independent cooling lines, using 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.