Maintenance engineering in the DEMO concept design phase policy and strategy for the development of a fusion power plant maintenance plan

The European Roadmap identifies the need of the DEMO project aiming to demonstrate that an economically competitive Fusion Power Plant (FPP) is possible before the full commercial deployment of fusion at industrial level. To guarantee the long-term economic viability of nuclear fusion this implies, that the integration of physics and all technological systems must enable a reliable and safe DEMO FPP ensuring a challenging 30 % for the required availability. One of the main contributors to the operational availability is guaranteed by the maintenance function. The function of maintenance engineering is first, to make systems more reliable by reducing FPP failure rates and second, to contribute to the reduction of downtimes required for the three main maintainability indicators involved in the availability equation. For any industrial power plant, the operational availability is impacted by downtimes required for preventive maintenance (scheduled) or corrective maintenance (unscheduled failure), supported by the integrated logistics (spare parts, tooling, facility, engineering documentation…). What is the maintenance policy and strategy needed to yearly guarantee the generation of 2628 hours electricity? This paper sheds light on the basic engineering elements of a robust maintenance policy and strategy, considered in the DEMO Concept Design (CD) phase for a FPP that will enable nuclear safety issues to be managed in a way that is compatible with an optimized life cycle cost. On this basis, the role of maintenance engineering is to define the architecture & data required to draw up a preventive maintenance plan. The paper will also specify the limits of the data that can be collected in the CD Phase, such as a contextual maintenance inventory set for a given work maintenance environment area or the degree of system design development for DEMO remote maintenance tools, especially those designed for corrective maintenance scenarios.