In pursuit of promoting the diversified development of energy cooperation demands among countries participating in the Belt and Road Initiative and address the demand for secure and efficient energy supply along the Belt and Road Economic Belt, Xi'an Jiaotong University has actively innovated and proposed a small modular fluoride-salt-cooled high-temperature advanced reactor FuSTAR.

This study aims to evaluate the load following capability and safety of the FuSTAR reactor.

The thermal-hydraulic modeling of the reactor body and the residual heat removal system of a small modular fluoride-salt-cooled high-temperature advanced reactor FuSTAR was conducted using conservation equations in macro form and point kinetics equations. Then, the one dimensional thermal fluid simulation program was used for modeling calculation and a constant coolant outlet temperature scheme was employed in the design of the control system for FuSTAR reactor by coupling simulation program with Simulink. Finally, the disturbance rejection characteristics and load following capability of the FuSTAR reactor were analyzed by inserting reactive disturbances and varying thermal load conditions.

Calculation results show that FuSTAR demonstrates load following capability without relying on an external control system, mainly due to its inherent safety features, which allow the reactor to self-stabilize and regulate under load variations. With the adoption of a constant coolant outlet temperature control scheme, the load following capability of FuSTAR has been further enhanced. In the tests of 10% FP (Full Power) load step change and 5% FP·min^-1 rate linear load rise and fall, the overshoot of nuclear reactor power is strictly controlled within 5%.

Results of this study indicate that FuSTAR has a good load following capability because of the negative temperature reactivity feedback and the existence of control system, which fully meets the requirements of safety operation of the reactor.