Extension and Validation of ATHLET Code for Thermal Energy Storage Simulation with Solar Salt

This article introduces the workflow of extending the ATHLET code to use solar salt as a thermal energy storage (TES) medium and its validation with the model of a natural circulation loop test facility. Thanks to ATHLET's modular structure, a plug-in was developed to implement the thermophysical properties of molten salts. The binary nitrate mixture solar salt was widely used in concentrated solar power (CSP) storage, considering its high cost-performance ratio, thermal stability, and broad operational window. To validate the code extension and implementation of salt properties, a simulation model was developed on the basis of Molten Salt Natural Circulation Loop (MSNCL) Testing. Both steady states and flow initiation transients were performed with a series of initial power levels in A THLET. Through comparison of the results and analysis of the thermal-hydraulic phenomena, the extension of ATHLET and the implementation of the salt's thermophysical properties were validated. The thermal dynamic behaviors of the MSNCL model can also reflect the characteristics of a scaled-up CSP system. This study represents the possibility of extending and utilizing a nuclear code in the field of renewable energy and further for broader applications across various energy systems.