In sodium-cooled fast reactors, the wettability of sodium with materials is closely related to sodium-related operations and the detection accuracy of instruments and meters, so how to achieve the selection of materials with different wettability requirements is a key problem in engineering design. To meet these requirements, the wetting behaviors of liquid sodium with nine transition metals were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and molecular dynamics (MD) simulations. The results show that metals such as zinc and gold, which react with sodium to form intermetallic compounds at the interface, exhibit superior wettability. Followed by the metals that have strong interatomic interactions even though they do not react with sodium or dissolve each other, such as cobalt, nickel and copper, while the wettability of these systems tends to be poor at low temperatures. Systems that do not react with each other or have strong interatomic affinities proved to be the most difficult to wet. Notably, metals with the closest-packed crystal structures of fcc and hcp generally have better wettability than those with a bcc structure. They can be a valuable guide for experimental research and technical control.

Since F/M steel is one of the leading candidate materials for the lead-cooled fast reactor (LFR), its compatibility with the liquid LBE environment is an essential issue before application. One major way to improve LBE corrosion resistance is to control the oxygen concertation in liquid LBE for the growth of a stable, protective oxide layer on the surface of the structure material. However, the influence of the surface state on corrosion behavior is a more realistic issue when it comes to practical applications. In this study, the corrosion behavior of Si-reinforced 9Cr and 11Cr F/M steels with different surface states was investigated by a static liquid LBE corrosion test under solid-phase oxygen-controlled conditions. The result showed that at 550 °C, the coarse surface state caused dissolution behavior at the initial stage of corrosion, while the fine surface state formed the oxide layer. Moreover, at 610 °C, Si-reinforced 11Cr F/M steel shows better liquid LBE corrosion resistance due to its thinner oxide layer formation.

In this study, slow strain rate tensile tests (SSRT) were performed on T91 in lead-bismuth eutectic (LBE) with saturated oxygen to investigate the effects of temperature (350 °C, 450 °C, and 550 °C), strain rate (1 × 10⁻⁵/s and 2 × 10⁻⁶/s) and pre-exposure conditions (time, oxygen concentration) on the sensitivity to liquid metal embrittlement (LME). The results revealed that the embrittlement sensitivity of T91 in LBE is significantly influenced by temperature. LME was observed in T91 at 350 °C and disappeared when the temperature increased to 550 °C. Additionally, T91 exhibited increased sensitivity to LME at low strain rates, indicating that low strain rates promoted the occurrence of LME. Finally, through different pre-exposure conditions, it was found that the obvious LME phenomenon would only occur when the oxygen concentration was poor and the pre-exposure time was long (48 h), indicating that pre-exposure conditions have a crucial impact on the occurrence of LME.

The loading and unloading elevators are the primary equipment in the refueling system, used for transferring fuel assemblies in the sodium-cooled fast reactors. The guideway friction pairs are the critical components of these elevators in the refueling system. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a promising material for the guideway friction pairs. In order to assess the feasibility of using nitrided W18Cr4V steel, it is essential to understand the aging behavior of nitrided W18Cr4V steel in high-temperature sodium. Aging tests were conducted on nitrided W18Cr4V steel in sodium and in argon environments at various temperatures for different exposure times. The results showed that the nitrogen atoms in the nitrided layer exhibited bidirectional diffusion behavior in the sodium or argon environment at 540 °C. Compared to the argon environment, cracks formed within the nitrided layer and the diffusion of nitrogen into the sodium was accelerated in the nitrided layer. As a significant number of nitrogen atoms had diffused into the sodium, there was little difference in the hardness between nitrided W18Cr4V steel and non-nitrided W18Cr4V steel after long-term exposure to 540 °C sodium.