The development of structural materials for fusion reactors

Abstract

Structural materials for first-wall and breeding-blanket components will be exposed to 14 MeV neutrons, plasma particles and electromagnetic radiation. In magnetically confined systems, the operation mode will be quasi-continuous. Typical operation conditions for next-step devices and demonstration plants will be described. The selection of suitable structural materials is based on conventional properties, their resistance to radiation-induced damage phenomena and the additional requirement of low neutron-induced radioactivity. Presently, low-activating ferritic-martensitic steels, vanadium alloys and ceramic composites are investigated as promising candidates. In the paper the present status of knowledge is reviewed and the critical issues for the different alternatives are elaborated. The necessity of an appropriate neutron source for the testing and qualification of the materials under fusion-specific conditions is also stressed.

Materials for the plasma-facing components of fusion reactors

“…Fusion specific grades like F82H and the European EUROFER grade show only a moderate shift of the ductile to brittle transition temperature DBTT. 10,11 In a recent irradiation experiment to a high dose of 32 dpa at 300°C irradiation temperature EUROFER showed an increase of the DBTT by 200 degrees from -100°C to +100°C. 12 However, this shift will be enhanced by irradiation with high energy neutrons typical for the fusion neutron energy spectrum.…”

“…The loading conditions of the materials for the plasma-facing components in ITER and in a first generation (DEMO-like) fusion reactor are listed in Table 1. In order to meet these requirements, three lines of development are being pursued: 10,11 Reduced activation ferritic-martensitic steels are currently the furthest developed technology. Vanadium alloys based on the V-Cr-Ti system have a great potential for high-temperature operation in combination with a liquid lithium breeder system.…”

HRTEM study of oxide nanoparticles in K3-ODS ferritic steel developed for radiation tolerance

“…In particular, the allowable power plant operating temperature, the choice of coolant, and the power conversion system are critically dependent on the structural materials. The selection of suitable structural materials is based on conventional properties (such as thermophysical, mechanical, and corrosion and compatibility), low neutron-induced radioactivity, and resistance to radiation-induced damage phenomena like material hardening/embrittlement and/or dimensional instability caused by void-and helium-driven swelling [1,2]. Reduced activation ferritic/martensitic (F/M) steels, which possess modified compositions of commercial ferritic/martensitic steels by exchanging Mo, Nb, and Ni with W, V, and Ta for low long-term radioactivity, have been selected as one of the primary candidate structural materials for fusion reactor applications because of their high thermal conductivity, good resistance to radiation-induced swelling and helium-induced embrittlement in experimental tests.…”

Segregation of voids in a spatially heterogeneous dislocation microstructure

“…[1][2][3] Given a broad range of challenging issues associated with the empirical testing of candidate materials in a simulated fusion environment, 1,4 modeling the microstructural evolution of materials has become a significant part of the international fusion development program. 5,6 The kinetics of phase transformations in materials driven far from equilibrium by irradiation is characterized by the dynamic balance between the creation of lattice defects and their annihilation at dislocations, grain boundaries, or other elements of the microstructure, and through clustering.…”