Dynamic Simulation of a Small Modular Sodium-Cooled Fast Reactor Coupled With Molten Salt Energy Storage System

Abstract The small modular sodium-cooled fast reactor plays a vital role in Generation-IV reactors, requiring the capability of load-follow operation to address the challenges posed by rapidly fluctuating electric loads on the power grid. Nevertheless, the thermal and mechanical stresses associated with load-follow operation can be undesirable for fuel and other reactor components. To address this, an alternative approach is proposed, focusing on operating the reactor at or near steady state and storing excess energy in a thermal heat storage system. The stored thermal energy can be efficiently utilized during periods of peak electric demand, effectively mitigating grid variability resulting from daily load demand changes and intermittent renewable energy sources. The sodium-cooled fast reactor is the most promising candidate for coupling with the molten salt thermal heat storage systems because the reactor coolant inlet and outlet temperatures of sodium-cooled fast reactors are in the margin of the molten salt working temperature. This study focuses on the integration of a molten salt energy storage system between the intermediate sodium loop and secondary loop of the modular sodium-cooled fast reactor. By employing this configuration, the coupled system enables the reactor to operate at nominal full power effectively, even during periods of variable electric demand. The research emphasizes the dynamic responses and control strategy of the coupled system. Initially, mathematical models for the small modular sodium-cooled fast reactor and molten salt energy storage system are proposed and implemented using MATLAB/SIMULINK. Subsequently, according to the operation strategies and control logics, the conventional PID control systems are designed for both the small modular sodium-cooled fast reactor and molten salt energy storage system. The dynamic simulations of load-follow scenarios are conducted to assess the performance of the small modular sodium-cooled fast reactor coupled with molten salt energy storage system. The simulation results demonstrate the feasibility of utilizing a molten salt energy storage system coupled with a small modular sodium-cooled fast reactor to efficiently minimize power swings during periods of variable electric load. Consequently, the coupled system significantly enhances the operational flexibility, safety, and cost-effectiveness of the sodium-cooled fast reactor, making it a promising and sustainable solution for ensuring grid stability and meeting the increasing energy demands of the future. Overall, this research contributes to advancing the state-of-the-art in small modular reactor technology, providing valuable insights into the integration of energy storage systems with sodium-cooled fast reactors, and showcasing the potential benefits in terms of enhanced operational performance, grid stability, and sustainability.