Influences of Fluorine on Corrosion Behavior of FeCrAl Alloy in Lithiated/borated Water at 360 °C/18.5 MPa

As an accident-tolerant fuel cladding material, Iron-Chromium-Aluminium (FeCrAl) alloy shows a big potential in replacing zirconium alloy as the cladding tube for pressurized water reactors. The presence of fluorine impurity in the primary coolant of pressurized water reactors will accelerate the corrosion of fuel cladding tubes. However, studies on the influences of fluorine impurity on the service performance of FeCrAl alloy are relatively limited. In this work, corrosion behavior of FeCrAl alloy in fluorine-containing lithiated/borated water at 360 °C and 18.5 MPa was characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), X-ray diffractometer (XRD), and Raman spectroscopy. The results indicate that FeCrAl alloy exhibited relatively good resistance to fluorine attack. Fluorine ions changed the diffusion behavior of alloying element Cr, so facilitating the formation and dissolution of FeCr₂O₄. Deposition of Ni and B was observed on the alloy surface. The maximum content of B reached 24.20 at.% after fluorine-containing lithiated/borated water exposure while that was 12.50 at.% in the absence of fluorine ions.