Short overview of flow-accelerated corrosion in CSP systems using molten nitrate salts: Mechanisms, challenges and outlook

Flow-Accelerated Corrosion (FAC) is an emerging concern in high-temperature thermal systems employing molten solar salts (60 wt% NaNO₃, 40 wt% KNO₃). Despite their extensive use in Concentrated Solar Power (CSP) plants, the behaviour of FAC in these media remains largely unexplored. This review provides the first integrated synthesis of hydrodynamic-driven corrosion in molten nitrate salts, linking flow conditions, electrochemical pathways, and welded material behaviour—an aspect absent from prior studies focused soley on static general corrosion. Emphasis is given to welded stainless steels (AISI 304 and AISI 347), where FeCr₂O₄ spinel formation governs corrosion resistance. The role of hydrodynamics and mass transfer, expressed through Sherwood, Reynolds, and Schmidt numbers, is highlighted as a key factor accelerating FAC in CSP systems.