The UK government’s ambition to establish a domestic fusion industry depends on a prototype power plant on the site of a former coal-fired power station in Nottinghamshire – a project delivered by UK Fusion Energy with the UK Atomic Energy Authority (UKAEA). Simulation capability lead Tom Deighan explains why advanced simulation and modelling technologies are bridging the gap between theoretical fusion and this first-of-a-kind tech demonstrator. Fusion is at an inflection point. Is that changing what work is being done? As a first-of-a-kind project, the biggest challenge is the absence of a previous fusion plant to refer to and understand how everything will perform. We have a number of experimental facilities, such as CHIMERA (Combined Heating and Magnetic Research Apparatus), under construction at UKAEA South Yorkshire, which will enable testing in a combined thermal and electromagnetic environment, and the LIBRTI (Lithium Breeding Tritium Innovation) programme, aiming to study and validate tritium breeding technologies. But these are looking at subsets of physics rather than the whole system. The challenge for engineers is how we deploy simulation effectively, along with the knowledge from these experiments, to build enough confidence in a full power plant design. How is your use of simulation technologies changing? Within fusion engineering, much of the work focuses on the impact of plasma on surrounding systems. That involves thermal-structural analysis and understanding how neutrons move through materials and structures. Traditionally, those analyses have been discrete, helping to answer specific questions or explain an experiment’s outcome. When you move to designing a full power plant, those questions need to be considered together. The focus now is on bringing those different simulation activities into combined workflows so we can understand system behaviour as a whole. A key part of that is improving how simulation links back to design. We need to