The challenge of developing structural materials for fusion power systems

Abstract

Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Central in the goal of designing a safe, environmentally benign, and economically competitive fusion power system is the requirement for high performance, low activation materials. The general performance requirements for such materials have been de®ned and it is clear that materials developed for other applications (e.g. aerospace, nuclear ®ssion, fossil energy systems) will not fully meet the needs of fusion. Advanced materials, with composition and microstructure tailored to yield properties that will satisfy the speci®c requirements of fusion must be developed. The international fusion programs have made signi®cant progress towards this goal. Compositional requirements for low activation lead to a focus of development e orts on silicon carbide composites, vanadium alloys, and advanced martensitic steels as candidate structural material systems. Control of impurities will be critically important in actually achieving low activation but this appears possible. Neutron irradiation produces signi®cant changes in the mechanical and physical properties of each of these material systems raising feasibility questions and design limitations. A focus of the research and development e ort is to understand these e ects, and through the development of speci®c compositions and microstructures, produce materials with improved and adequate performance. Other areas of research that are synergistic with the development of radiation resistant materials include fabrication, joining technology, chemical compatibility with coolants and tritium breeders and speci®c questions relating to the unique characteristics of a given material (e.g. coatings to reduce gas permeation in SiC composites) or design concept (e.g. electrical insulator coatings for liquid metal concepts). Ó

A Review of Dangerous Dust in Fusion Reactors: from Its Creation to Its Resuspension in Case of LOCA and LOVA

“…These challenges are faced by the production of advanced material with unique performances [74][75][76][77][78], these material include ferritic/martensitic steels, V-Cr-Ti alloys and SiC/SiC ceramic composites.…”

Hydrogen release from irradiated vanadium alloy V–4Cr–4Ti

“…The interest in the vanadium based alloy V-4Cr-4Ti for fusion application is connected with its excellent resistance to radiation swelling, low induced radioactivity and good thermal conductivity [1]. If we consider possible future application of this alloy as a DEMO breeder blanket material, its behavior with respect to hydrogen isotope retention will be very important, particularly at temperatures typical of those in a breeding blanket, which could be up to 800 C [2].…”

The Mission and Technology of a Gas Dynamic Trap Neutron Source for Fusion Material and Component Testing and Qualification

“…The resulting microstructural and damage evolutions cause profound macroscopic property changes that severely degrade the performance and lifetime limits of first wall components [11][12][13][14][15] . As reviewed recently by Zinkle 14 , the observed property changes of irradiated materials depend on the irradiation temperature and other environmental variables and have been called the 'scourges of irradiation', and include irradiation hardening and embrittlement, phase and dimensional instability and He embrittlement.…”

“…The most important variables include the initial material microstructure, the thermal mechanical loads and irradiation history. Yet, radiation damage is the overarching concern for first wall and breeding blanket structures [11][12][13][14][15] .…”

“…Concurrently, high concentrations of insoluble helium and hydrogen gas are generated in (n,α) and (n,p) neutron capture reactions, which have threshold energies above several MeV, hence are not normally produced in high quantities in fission neutron irradiations [11][12][13][14][15] . The primary knock-on atoms, as well as recoiling transmutant nuclei quickly lose kinetic energy through a chain of atomic collision displacements, generating a displacement cascade of vacancy and self-interstitial defects, in addition to electronic excitations.…”