Contribution to safety analyses of DEMO HCPB using AINA code

Abstract

The motivation of the current work, framed under the safety EUROfusion activities to develop DEMO, is to present the conclusions drawn from our contribution to the safety studies of the HCPB DEMO carried out by the team tasked with AINA code development. During 2016 and 2017 a new AINA version was built in order to evaluate plasma evolution and in-vessel components strains inside the European DEMO designs. As a result, AINA is able to foresee several accident scenarios as plasma disruptions or structural meltings due to LOPCs (Loss Of Plasma Control) and in-vessel melt either of FW, blanket structure and/or divertor modules because of thermal stresses due to LOCAs. After due analysis, it has concluded that it would be desirable to carry out a design review focused on ensuring a suitable operating temperature range with a bigger safety margin for all the materials which make up the HCPB BB, as well as the need to guarantee a quick detection and actuation by means of a proper system, depending on the affected equipment, when the most demanding transients take place which may drive the reactor to melting scenarios and very energetic plasma disruptions. These events include an increase of fueling above 50%, a permanent improvement in the confinement time and a punctual impurity increase above 300%. Other perturbations has been studied which provide information on non-dangerous cases, impossible situations or melting processes.