Service Joining Strategy for the EU DEMO

As part of the European Research Roadmap to the Realisation of Fusion Energy, the DEMO reactor aims to show the feasibility of a fusion power plant. Due to the loss of revenue created by downtime and the potential for a breakdown to render a reactor inoperable, maintenance is “mission critical” for a power plant. The harsh environment of a fusion reactor dictates that maintenance must be carried out remotely, which requires the development of new strategies and technologies. There are many challenges to be solved, one of which is how to manage service connections. Within DEMO, the plasma-facing, first-wall components will be the most challenging to connect services to, due to the number of connections and operational environment. High speed, highly reliable cutting and welding tools are required to minimise downtime and mitigate the danger of rendering the reactor inoperable. Uniquely, these tools are required to operate wholly in-bore to allow the current pipe density in the DEMO architecture, something that is not available from industry. Here, the development of a Service Joining System to meet the DEMO scenario is presented. The joining strategy is discussed along with the substantiation of the design solution. The results of proof-of-principle trials to date are discussed and their implications for the strategy considered. Having discussed feasibility for DEMO, a roadmap is presented for the development of the Service Joining System to an appropriate Technology Readiness Level.