The challenge of developing structural materials for fusion power systems

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 f usion power system is the requirement for high performance, low activation materials. The general performance requirements for such materials have bee n defined and it is clear that materials developed for other applications ( e.g. aerospace, nuclear fission, fossil energy systems) will not fully meet the needs of fusion. Advanced materials, with composition and microstructu re tailored to yield properties that will satisfy the specific requirements of fusion must be developed. The international fusion programs have made s ignificant progress towards this goal. Compositional requirements for low a ctivation lead to a focus of development efforts on silicon carbide composi tes, vanadium alloys, and advanced martensitic steels as candidate structur al material systems. Control of impurities will be critically important in actually achieving low activation but this appears possible. Neutron irradi ation produces significant changes in the mechanical and physical propertie s of each of these material systems raising feasibility questions and desig n limitations. A focus of the research and development effort is to underst and these effects, and through the development of specific compositions and microstructures, produce materials with improved and adequate performance. Other areas of research that are synergistic with the development of radia tion resistant materials include fabrication, Joining technology, chemical compatibility with coolants and tritium breeders and specific questions rel ating to the unique characteristics of a given material (e.g. coatings to r educe gas permeation in SiC composites) or design concept (e.g. electrical insulator coatings for liquid metal concepts). (C) 1998 Elsevier Science B. V. All rights reserved.