Identification of Design Drivers through Technology Feasibility Studies of First Wall Protection Systems
The Limiter (LIM) System of a port-based tokamak like the EU-DEMO in [1] encompasses different kind of limiters for first wall protection purposes. Among them, four outboard lower limiters (OLL) are foreseen for protecting the first wall against heat loads arising from downward Vertical Displacement Events. Although the poloidal surface extension is identified under plasma physics inputs and verified under charged particle heat loads by means of field line tracing, no dedicated Vacuum Vessel openings are foreseen in the lower outboard first wall, precisely behind the OLL. On one hand, limiters should be designed to protect the first wall against energy depositions following plasma disruptive events; on the other side, though, it is important ensuring that the protection system is designed under realistic constraints to be easily handled and realistically maintained. Therefore, integration and remote maintenance requirements and needs become an important factor affecting the integrated engineering design of the OLL, for which a dedicated handling strategy becomes one of the main drivers, together with physics needs.
The paper presents the rationale driving the design of the OLL, and the remote maintenance strategy supporting its design concept. The definition of the handling strategy will help identify robust design drivers that apply to the entire lifecycle of the OLL and improve the feasibility of achieving a practicable design solution compatible with its remote maintenance at every stage.
[1] M.L. Richiusa et al., The Integrated Engineering Design of the Upper Limiter within the LIM System. Fusion Engineering and Design, 2024.