Analysis of the Limiting Safety System Settings of a Fluoride Salt–Cooled High-Temperature Test Reactor

The fluoride salt–cooled high-temperature reactor (FHR) is an advanced reactor concept, which uses high-temperature TRISO fuel with a low-pressure liquid salt coolant. The design of a fluoride salt–cooled high-temperature test reactor (FHTR) is a key step in the development of the FHR technology and is currently in progress in both China and the United States. An FHTR based on a pebble bed core design with coolant temperature 600°C to 700°C is being planned for construction by the Chinese Academy of Sciences’ Thorium Molten Salt Reactor Research Center, Shanghai Institute of Applied Physics (SINAP). This paper provides a preliminary thermal-hydraulic licensing analysis of an FHTR using SINAP’s pebble core design as a reference case. The operation limits based on criteria outlined in U.S. regulatory guidelines are evaluated. Limiting safety system settings (LSSSs) considering uncertainties for forced convection and natural convection are obtained. The LSSS power and coolant outlet temperature, respectively, are 24.83 MW and 720°C for forced convection and 1.19 MW and 720°C for natural convection. The maximum temperature for the structural materials of 730°C is the most limiting constraint of the FHTR design.