Some implications of radiation-induced property changes in austenitic stainless steels on ITER [International Thermonuclear Experimental Reactor] 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 degree 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 degree C, to have higher irradiation-creep rates at 60 degree C than at 200--400 degree C, and to show radiation-induced changes in electrochemical properties at 200--400 degree 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 degree 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 degree C. The higher initial yield-strength of CW 316 will allow higher design stress and elastic strain limits. 31 refs., 10 figs