Some Implications of Radiation-Induced Property Changes in Austenitic Stainless Steels on ITER First-Wall Design and Performance

New data on radiation-induced hardening, low-temperature creep and potential susceptibility (sensitization) to aqueous corrosion have been obtained on various heats of austenitic stainless steel (including type 316) irradiated at 60–400°C to 7–13 dpa. The data were obtained from spectral-tailoring reactor experiments, whose radiation-damage parameters are similar to those in the proposed International Thermonuclear Experimental Reactor (ITER) first-wall (FW) and blanket design. Austenitic stainless steels were found to increase significantly in strength at 60–330°C, to have higher irradiation-creep rates at 60°C than at 200–400°C, and to show radiation-induced changes in electrochemical properties at 200–400°C. These data on several radiation-induced property changes suggest that type 316 steel may be an adequate material for the FW of ITER. However, there is definitely a need for new data on fracture-toughness and on fatigue behavior below 400°C, as well as more data on irradiation-creep and effects of irradiation on corrosion properties, to better define temperature and dose dependencies for more detailed design analyses. Cold-working should remain an optional as-fabricated condition for the FW of ITER. Many properties of SA and CW 316 become similar after irradiation at 60–400°C. The higher initial yield-strength of CW 316 will allow higher design stress and elastic strain limits.