Structural assessment of the HCPB breeding blanket segments in the EU DEMO reactor under normal operation and a central plasma disruption

The aim of the work reported in this paper is to evaluate the structural integrity of the Helium Cooled Pebble Bed (HCPB) breeding blanket segments in the EU DEMO reactor under the boundary conditions given by the current version of the attachment system, which connects the segments to the vacuum vessel. A 3D model of a DEMO sector has been developed using the FE software ANSYS and thermo-mechanical analyses are performed considering thermal and mechanical loads under normal operation as well as additional EM loads during a central plasma disruption. The results of the structural analysis are presented and the stresses on the back supporting structure of the breeding blanket segments are evaluated taking into account the RCC-MRx code. The design of back supporting structure fulfills the required criteria for the normal as well as the considered off-normal operation conditions. With respect to the iterative development process, these results represent an important input for the further optimization of the design of the attachment system.