Towards reduced activation structural materials data for fusion DEMO reactors

TLDR

Developing long‑lived first‑wall, blanket, and divertor materials that can withstand high neutron and heat fluxes is a critical path to fusion power, and a timely, comprehensive materials database is essential for international fusion road maps and for understanding radiation damage across dpa ranges up to 75 dpa. The study aims to supply ITER TBM and DEMO fusion reactor design data by characterizing EUROFER and oxide‑dispersion‑strengthened steels at 250–650 °C, and to develop high‑temperature SiCf/SiC channel inserts for liquid‑metal coolant tubes to boost blanket thermal efficiency. The approach involves irradiating EUROFER and oxide‑dispersion‑strengthened steels up to 15 dpa in the HFR and 75 dpa in BOR60, producing industrial EUROFER batches of 3.5 and 7.5 t in semi‑finished forms, developing high‑temperature SiCf/SiC channel inserts for liquid‑metal coolant tubes, and establishing a materials database for pure W and alloys at 650–1000 °C.

Abstract

The development of first wall, blanket and divertor materials that are capable of withstanding for many years high neutron and heat fluxes, is a critical path to fusion power. Therefore, the timely availability of a sound materials database has become an indispensable element in international fusion road maps. In order to provide materials design data for the short-term needs of ITER test blanket modules (TBMs) and for a DEMOnstration fusion reactor, a wealth of R&D results on the European reduced activation ferritic–martensitic steel EUROFER, and on oxide dispersion strengthened variants are being characterized, mainly in the temperature window 250–650°C. The characterization includes irradiations up to 15 dpa in the mixed spectrum reactor HFR and up to 75 dpa in the fast breeder reactor BOR60. Industrial EUROFER-batches of 3.5 and 7.5 tons have been produced with a variety of semi-finished, quality-assured product forms. To increase the thermal efficiency of blankets, high temperature resistant SiCf/SiC channel inserts for liquid metal coolant tubes are also developed. Regarding radiation damage resistance, broad based reactor irradiation programmes deal with several ranges from ≤ 5 dpa (ITER TBMs) up to 75 dpa (DEMO). For the European divertor designers, a materials database is currently being set up for pure W and its alloys, and related reactor irradiations are foreseen with temperatures from 650°C to 1000°C.