Preliminary thermal-hydraulic analysis of the EU-DEMO Helium-Cooled Pebble Bed fusion reactor by using the RELAP5-3D system code

In the frame of activities promoted and encouraged by EUROfusion Consortium aimed at developing EU-DEMO fusion reactor, great emphasis has been placed a very early stage design to incorporate provisions needed improve overall plant safety reliability performances as well analyse possible mitigation actions. this framework, research activity focused on representative relevant cooling loop Helium Cooled Pebble Bed (HCPB) Breeding Blanket (BB) Primary Heat Transfer System (PHTS), purposely selected team, in order assess its thermal-hydraulic behaviour during normal operational conditions (ramp up/down steady state) preliminarily investigate consequences an ex-vessel LOCA accidental scenario ensuing Double-Ended Guillotine (DEG) break hot leg. The carried out following theoretical-computational approach based finite volume method adopting RELAP5−3D system code along with ANSYS CFX computational fluid dynamic code, which were implicitly integrated achieve more detailed realistic simulation reactor thermal-hydraulics. Models, assumptions outcomes preliminary study are herein presented critically discussed.