Corrosion Behavior of Austenitic Steels and an Iron–Nickel 06KhN28MDT Alloy in Uranium-Containing Fluoride Melts

The development of advanced generation IV technologies, such as a molten salt reactor-burner nuclear power plant (MSR-B NPP), requires progressive and innovative solutions. The implementation of the MSR-B NPP necessitates a final resolution to the problem of selecting structural materials capable of maintaining corrosion resistance under reactor operating conditions, namely, under the influence of high temperatures, aggressive media, and inherent neutron irradiation. Corrosion-resistant steels are considered as promising candidate structural materials. In this work, ampule-type corrosion tests of austenitic 12Kh18N10T and SS 316L steels and an iron-nickel-based 06KhN28MDT alloy are performed. The corrosion tests are carried out in a melt based on the LiF–KF–NaF (FLiNaK) eutectic mixture with a uranium tetrafluoride addition, FLiNaK + UF4 (5 wt % UF4), in the temperature range 650–750°C for 100 h under isothermal conditions (static mode, implying no melt movement in the working space). The aim of this study is to analyze and compare the corrosion properties of the chosen materials in the FLiNaK + UF4 (5 wt %) melt and to determine the mechanisms of the observed corrosion processes.