Recent In-Vessel Integration Concepts for a European DEMO Reactor

A part of the recent scoping studies for a European DEMO reactor deals with the design of the in-vessel components and their integration inside the reactor. The main in-vessel components are the Breeding Blankets (Helium Cooled Lithium Lead and Helium Cooled Pebble Bed), the helium supply units called Manifolds (MF) and the Neutron Shields. Alternative concepts for the integration of these components have been developed in parallel by different Europe an associations (FZK, CEA, and EFET). Nevertheless these concepts are all based on the vertical segmentation concept called "Multi Module Segment" (MMS). The big advantage of the MMS concept dwells in the fact that blankets and MF constitute a vertical non-permanent segment to be installed and dismantled by Remote Handling (RH) tools through the upper ports of the reactor. The dimensions, geometry and materials are strictly dependent on the harsh conditions of the in-vessel environment: high temperatures, high neutron fluxes, and high thermo-mechanical loads during normal operations and disruptive events. In addition, suitable systems of attachment able to withstand thermal expansion and the expected loads have been developed to provide reliability and easy in-vessel maintenance. The general aspects of the MMS system and the common RH procedures foreseen are presented and the different specific options for solving attachment and in-vessel assembly issues are discussed.