DEMO maintenance scenarios: Scheme for time estimations and preliminary estimates for blankets arranged in multi-module segments

The paper presents a comprehensive maintenance scheme for the multi-module segments (MMSs) blanket complete with machine concepts, logistics and flexible time estimations. The main features of this scenario are: two upper, vertically arranged maintenance ports have to be opened for blanket maintenance on opposite sides of the tokamak. The MMSs are removed and inserted through both ports which are handled in parallel and independently. Inside the vessel maximum four in-vessel machines are operating to transport the elements in toroidal direction and also to insert and attach the MMS to the shield. Outside the vessel the elements have to be transported between the tokamak and the hot cell (also with two ports) either in casks or through a corridor. For this scenario corresponding maintenance times were calculated utilizing the industrial experience of Areva NP. The paper presents preliminary time estimates for the cask scenario as well as the corridor concept, and the obtained results show good potential for a high availability reactor.