Traditional nuclear reactors rely on dense fuel rods submerged in water to manage the immense heat generated by fission reactions. Molten salt reactors, in contrast, use liquid fuel dissolved in a molten salt mixture, operating at temperatures exceeding 800 degrees Celsius. This design offers significant advantages, such as improved safety margins, continuous fuel processing, and enhanced thermal efficiency. However, the aggressive chemical environment posed by the molten salts accelerates corrosion in metals, threatening reactor integrity.

The Penn State team employed advanced reactive simulations on the ROAR supercomputer to model how different atomic structures within nichrome alloys respond when exposed to FLiNaK molten salt, a popular mixture used in these reactors. Crucially, they examined the impact of atomic ordering—the degree to which chromium and nickel atoms arrange themselves in short- or long-range patterns within the alloy.

Their simulations demonstrated that long-range atomic ordering forms interconnected “corrosion highways.” These pathways allow corrosive species to rapidly penetrate the metal from the surface inward, causing severe pitting and roughening of the alloy in mere nanoseconds. In contrast, alloys with short-range ordering or random atomic arrangements showed significantly better resistance to corrosion under identical conditions, maintaining smoother surfaces.

This breakthrough reveals that corrosion susceptibility is not merely a function of chemical composition but heavily influenced by microstructural atomic organization. “Understanding these percolation pathways gives us predictive power over corrosion behavior, enabling us to design alloys tailored to withstand molten salt environments,” explains Hamdy Arkoub, co-corresponding author and doctoral candidate in nuclear engineering.

The study addresses long-standing challenges in experimentally characterizing corrosion under extreme reactor conditions, such as intense radiation and high temperatures, by using high-fidelity computational modeling. This approach allows researchers to observe real-time atomic interactions during corrosion processes that unfold over billionths of a second, an impossible feat in laboratory settings.

This new atomic-level insight paves the way toward engineering more durable structural materials for molten salt reactors, advancing their commercialization potential. The work, to be published in Corrosion Science, represents a crucial step in overcoming one of the key hurdles in developing safer and more efficient nuclear power systems capable of meeting future energy demands.

Subject of Research: Materials corrosion in nuclear reactors
Article Title: Percolating corrosion pathways of chemically ordered NiCr alloys in molten salts
News Publication Date: May 22, 2026
Web References: https://doi.org/10.1016/j.corsci.2026.113960
References: https://doi.org/10.1016/j.apsusc.2024.159627; https://doi.org/10.1021/acsomega.6c03055; https://doi.org/10.1021/acsami.5c06557
Image Credits: Provided by Hamdy Arkoub

Keywords

Corrosion, Chemical processes, Nuclear engineering, Molten salt reactors, Nickel-chromium alloys, Atomic ordering, Nuclear power safety