Research and development status on fusion DEMO reactor design under the Broader Approach

•Latest status of the DEMO design activity under the Broader Approach.•Start points of DEMO parameter scoping study.•DEMO divertor study aiming at detached plasma with impurity injection and magnetic flux tube expansion by advanced divertor configurations.•Assessment of possible remote maintenance schemes for DEMO.

The main objective of DEMO design activity under the Broader Approach is to develop pre-conceptual design of DEMO options by addressing key design issues on physics, technology and system engineering. This paper describes the latest results of the design activity, including DEMO parameter study, divertor and remote maintenance. DEMO parameter study has recently started with “pulsed” DEMO having a major radius (Rp) of 9 m, and “steady state” DEMO of Rp = 8.2 m or more. Divertor design study has focused on a computer simulation of fully detached plasma under DEMO divertor conditions and the assessment of advanced divertor configuration such as super-X. Comparative study of various maintenance schemes for DEMO and narrowing down the schemes is in progress.