Issues of the vertical blanket segment architecture in DEMO: Current progress and resolution strategies

Due to the limited irradiation lifetime of the structural material used for in-vessel components in DEMO, it will be necessary to replace all breeding blankets within the given planned maintenance window in order to meet DEMO availability targets (Romanelli, 2012; Ellis, 2017) [ 1 , 2 ]. It is assumed that failure of in-vessel components cannot be excluded, whilst in-situ repair is unrealistic. Hence the replacement of individual breeder blankets must be technically feasible. As such, remote maintenance replacement of the breeding blankets is a mission critical operation. The baseline concept utilises vertical segment architecture to aid in the removal of the blankets (Iglesias, 2013) [ 3 ]. This choice impacts on the tokamak and plant architecture and also affects operational maintenance strategy. Within the EUROfusion PPPT program efforts have been made to perform cross work package investigations on eight Key Integration Issues needed to show the feasibility of the DEMO pre-concept design (Bachmann, 2017) [ 4 ]. Key Design Issue 4 is an investigation into the feasibility of the Vertical Segment Architecture blanket feasibility The present work documents the approach, current progress and developments within this investigation. This includes the strategy, identified risks and proposed solutions.