Fusion reactor safety boosted by breakthrough in weld analysis

Working in collaboration with the UK Atomic Energy Authority (UKAEA), the National Physical Laboratory, and TESCAN, the researchers from Surrey University have developed and used an advanced microscopic method to map weaknesses inside welded metals during manufacturing that can compromise reactor components and reduce their lifespan. 

The research, published in the Journal of Materials Research and Technology, details how they examined P91 steel, which is a candidate for future fusion plants.

The researchers applied an advanced imaging technique using a plasma focused ion beam and digital image correlation (PFIB-DIC) to map residual stress in ultra-narrow weld zones that were previously too small to study with conventional methods. 

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Results showed that internal stress has a big impact on how P91 steel performs with beneficial stress making some areas harder and detrimental stress making others softer, which affects how the metal bends and breaks. At 550°C the metal became more brittle and lost more than 30 per cent of its strength.