The US program to develop structural materials for near- and long-term fusion systems

The U.S. structural materials program is pursuing a near-term effort related to the International Thermonuclear Experimental Reactor (ITER) and a long-term effort related to the development of reduced-activation materials for future power systems. The response of the principal ITER structural materials, austenitic stainless steels and copper alloys, to ITER irradiation conditions has been explored using fission reactor facilities. The primary radiation damage phenomena have been identified and the neutron dose and temperature conditions have been determined which will ensure adequate ductility during ITER operation. A new, reduced activation ferritic-martensitic steel has been shown to have exceptionally promising resistance to low temperature radiation embrittlement. A newly-developed V-Cr-Ti alloy has been successfully produced on a commercial scale and is being used to fabricate components for the DIII-D Radiative Divertor; recent experimental data on the irradiation performance of this alloy are discussed. Sources of radiation-induced property changes in SiC composite materials have been identified and strategies developed to improve mechanical performance of these materials during irradiation. (author)