Design studies of the ASTRID nuclear island are conducted in accordance with GEN IV reactors criteria, in particularly for safety and operability improvement.

The latest configuration of ASTRID nuclear island (including primary and secondary circuits) has been produced by Framatome at the end of 2017 corresponding to the middle of the Basic Design phase.

This paper describes the main ASTRID safety and operational requirements and the up-to-date design options, focusing on innovative options. Items addressed in the paper include: vessels (main and safety vessels), core support structures, primary pumps and pumps-diagrid connecting pipes, Above Core Structure, Intermediate Heat eXchangers, internal vessel, upper closures (slab and rotating plugs), Decay Heat Removal systems and core catcher. The global architecture of the primary and secondary circuits, in connection with the Gas Power Conversion System, is also presented.

This paper reports on the progress of the studies concerning:

- thermal hydraulics and thermal mechanics,

- evaluations of the seismic resistance,

- in-service inspection,

- qualification needs.

Lastly, it indicates the open options for materials, components and general architecture, which will continue to be studied in the second half of the Basic Design phase.