UK tests first remountable nuclear fusion magnets for 'plug in' power

Engineers involved in the UK’s STEP (Spherical Tokamak for Energy Production) program have successfully tested a novel “plug-and-socket” magnet technology featuring Remountable Joints (RMJs). This innovation allows massive fusion magnets—traditionally built as permanent, solid structures—to be disassembled and reassembled for maintenance, addressing a major engineering challenge in tokamak fusion reactors. By enabling easier internal repairs and component replacements, the RMJs are expected to reduce downtime, lower operational complexity, and cut costs, thereby improving the commercial viability of fusion power plants. Complementing the RMJs, the team developed a unique bladder-based mechanical clamping system that uses a liquid-filled bladder expanding upon freezing to maintain even contact pressure at cryogenic temperatures. This ensures magnet stability and efficiency under the extreme mechanical forces generated during fusion. The clamping system is being prepared for patenting and is designed for scalable manufacturing using various industrial techniques, supporting a robust UK supply chain. STEP aims to demonstrate these technologies in realistic