Scientists in the UK have forged 5.5 tonnes of a new kind of steel capable of withstanding the searing heat and intense neutron radiation of nuclear fusion, the same reaction that powers the Sun and stars. The breakthrough is another boost to Europe’s growing flock of fusion energy startups. A UK Atomic Energy Authority (UKAEA) working group called NEURONE produced the reduced-activation ferritic-martensitic steel, or “RAFM” for short.