As countries race to build the first working nuclear fusion power plants, engineers at the University of Surrey have made an important discovery that could help future reactors last longer and operate more safely.
By studying how welded parts behave under extreme heat—like that inside a fusion reactor—the team has developed a better way to understand and fix weaknesses in the materials used to build these powerful machines.
The researchers worked with the UK Atomic Energy Authority, the National Physical Laboratory, and scientific equipment company TESCAN.
Together, they created and used a powerful imaging technique to look deep inside welded steel at the microscopic level.
This new method, called PFIB-DIC (plasma-focused ion beam and digital image correlation), allows them to see stress in very narrow weld zones that were previously too small to study.
They focused on a special metal called P91 steel, which is strong and resistant to heat, making it a top candidate for use in fusion reactors.
What they found was that the internal stress caused by welding can change how strong the metal is.
Some stress actually strengthens the steel, while other stress makes it weaker and more likely to crack. At the high temperatures expected in a fusion plant—around 550°C—the steel became much more brittle and lost over 30% of its strength.
Dr. Tan Sui, who led the research, explained that fusion power has the potential to provide clean, reliable energy and reduce carbon emissions.
But to make it a reality, fusion reactors must be safe and long-lasting.
Past studies didn’t test materials at high enough temperatures, so the team wanted to see how welded joints really perform in conditions closer to those in future fusion plants.
Fusion energy works by fusing small atoms together, just like in the sun, to release a lot of energy. It produces less harmful waste than traditional nuclear power and uses more abundant materials. To help fusion energy move from lab to power grid, scientists need accurate ways to predict how materials will behave.
The findings from this study will help improve computer models and machine learning tools used in reactor design. These tools can now be trained with real-world data, helping to speed up the development of commercial fusion power plants like the UK’s STEP program and Europe’s DEMO project.
This research offers a new way to check how safe and strong metal joints are, not only for fusion but for any environment with extreme heat. It brings us one step closer to making fusion energy a practical and sustainable power source for the future.
