Design space exploration for salt-cooled reactor system: Part I – Thermal hydraulic design

•Feasibility study of utilisation of AGR technology towards the development of FHR system is carried out.•Design space exploration using thermal-hydraulic and economic analysis of the new system.•The optimisation space is analysed to find the best candidate for a hybrid AGR-FHR system.•The best performing configurations, with the most favourable optimisation parameters, were those with the minimum amount of graphite. Fluoride-salt-cooled High-temperature Reactors (FHRs) are a variant of nuclear reactor offering high power densities and operating temperatures. This paper proposes a new design stream of FHR, leveraging developments and experience from the British Advanced Gas-cooled Reactor (AGR) fleet, the only commercial fleet of high-temperature reactors to-date. The design space for the proposed AGR-like FHR is explored using a thermal-hydraulic simulation and optimisation package, seeking to maximise the reactor’s economic performance. Starting from a salt-cooled AGR assembly and applying reasonable thermal-hydraulic constraints, this exploration includes varying the assembly fuel type and geometry, coolant salt, as well as design of the pumps and heat exchangers. Some of the resulting designs promise substantially higher power densities than AGRs and improved economics.