Towards reduced activation structural materials data for fusion DEMO reactors

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 SiC f /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.

Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part I: undamaged steels

“…These systems are desired to operate at relatively high temperatures up to 650 С. RAFM steels possess exceptional thermal conductivity and low thermal expansion among other steels while being strongly resistant to void swelling. The RAFM steels such as Eurofer97, F82H and Rusfer were developed in Europe [4,5], Japan [6], and Russia [7], respectively. Their composition lies in the following range: Fe-(7.5-12)Cr-(1.1-2)W-(0.15-0.25)V, in weight percent.…”

Mechanism of Radiation Damage Reduction in Equiatomic Multicomponent Single Phase Alloys

“…However, in the particular case of nuclear reactors, there is the additional complication of radiation damage. In particular, realization of new Generation IV fission reactor concepts [9,10], that will have many improved features (e.g., the capability to burn used nuclear fuel), as well as tokamaklike fusion power plants [10,11], will both subject materials in the reactors to very high neutron irradiation loads. Hence, to realize the great potential of equiatomic and high-entropy alloys in nuclear environments, it is crucial to consider also radiation damage and its buildup in these materials.…”

Materials selection for nuclear applications: Challenges and opportunities

“…A good example is selecting and designing fusion materials. The nuclear-fusion community has made significant effort to develop and characterize reduced-activation ferritic/martensitic steels (RAFM) [7,8]. The goal is to design ferritic/martensitic materials that have specific physical properties (high-temperature strength, radiation tolerance) and exhibit as little as possible activation and transmutation of alloying elements into radioactive isotopes because these effects make maintenance of a fusion plant difficult and increase the amount of radioactive waste that must be stored.…”