Materials requirements for fusion reactors

Once the physics of fusion devices is understood, which is expected to be achieved in the early 1980’s, one or more experimental power reactors (EPR) are planned which will pro-duce net electrical power. The structural material for the device will probably be a modi-fication of an austenitic stainless steel. Unlike fission reactors, whose pressure bound-aries are subjected to no or only light irradiation, the pressure boundary of a fusion reac-tor is subjected to high atomic displacement-damage and high production rates of trans-mutation products,e.g., helium and hydrogen. Hence, the design data base must include irradiated materials. Sincein situ testing to obtain tensile, fatigue, creep, crack-growth, stress-rupture, and swelling data is currently impossible for fusion reactor conditions, a program of service-temperature irradiations in fission reactors followed by postirradi-ation testing, simulation of fusion conditions, and low-fluence 14 MeV neutron-irradiation tests are planned. For the Demonstration Reactor (DEMO) expected to be built within ten years after the EPR, higher heat fluxes may require the use of refractory metals, at least for the first 20 cm. A partial data base may be provided by high-flux 14 MeV neutron sources being planned. Many materials other than those for structural components will be required in the EPR and DEMO. These include superconducting magnets, insulators, neutron reflectors and shields, and breeding materials. The rest of the device should utilize conventional materials except that portion involved in tritium confinement and re-covery. This paper is based on a presentation made at a symposium on “Materials Re-quirements for Unconventional Energy Systems” held at the Niagara Falls meeting of The Metallurgical Society of AIME, September 22, 1976, under the sponsorship of Non-Ferrous Metals and Ferrous Metals Committees.