Study on the corrosion behavior of 316H stainless steel in molten NaCl–KCl–MgCl_(2) salts with and without purification

The corrosion behavior of 316H stainless steel(SS)in the impure and purified Na Cl–KCl–Mg Cl_(2) salt was investigated at700°C.Results indicate that the main deleterious impurity induced corrosion in the impure salt was the absorbed moisture,present in the form of Mg Cl_(2)·6H_(2)O.316H SS occurred severe intergranular corrosion with a corrosion depth of 130μm for1000 h in the impure Na Cl–KCl–Mg Cl_(2) salt.In contrast,the purification treatment of molten chloride salt by the dissolved Mg metal can remove the absorbed moisture,and the corresponding reactions were also discussed.As a result,the corrosiveness of Na Cl–KCl–Mg Cl_(2) salt is reduced significantly.316H SS occurred slight uniform corrosion with a depth of less than 5μm for 3000 h in the purified Na Cl–KCl–Mg Cl_(2) salt.

Synchrotron radiation-based materials characterization techniques shed light on molten salt reactor alloys

From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion,tellurium(Te) corrosion, and alloy design. The valence states and distribution of chromium(Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.

A potential candidate structural material for molten salt reactor:ODS nickel-based alloy

The commercialisation of molten salts reactors(MSRs)is hindered by the lack of structural materials capable of withstanding the corrosive environment therein.To address this problem,we herein prepared1 wt%Y_(2)O_(3)mdispersion-strengthened Ni Mo-based alloys using powder metallurgy and evaluated their potential as structural materials for MSRs based on their mechanical properties,He swelling behaviour,and molten salt corrosion resistance.In view of the strengthening provided by homogenously dispersed Y_(2)O_(3)particles,all NiMo-Y_(2)O_(3)samples exhibited ultimate tensile strengths and yield strengths exceeding those of the Hastelloy N alloy,a state-of-the-art structural material for MSRs.Moreover,the volume fraction of He bubbles in the NiMo-Y_(2)O_(3)samples(~0.3%)was lower than that in the Hastelloy N alloy(0.58%),which showed that the introduction of Y_(2)O_(3)nanoparticles effectively inhibited He swelling.All NiMo-Y_(2)O_(3)samples showed excellent resistance to molten salt corrosion(as reflected by the absence of obvious holes therein),thus holding great promise for the development of irradiation-and molten salt corrosion-resistant structural materials for high-temperature MSRs.