The relationship between swelling and irradiation creep in 20% cold-worked 316 stainless steel

The relationship between swelling and irradiation creep was investigated using eight sets of pressurized tubes, representing two heats of 20% cold-worked 316 stainless steel irradiated at either 550 degrees C, 575 degrees C, 600 degrees C, and 670 degrees C in the FFTF-MOTA to doses of 79-83 dpa. After reaching these exposures, the tubes were clearly being affected by the "creep cessation" phenomenon. Many of the tubes had already reached the previously observed maximum strain rate of 0.33%/dpa characteristic of creep cessation. Fortuitous failure of fourteen tubes allowed the separation of creep and swelling strains in the creep cessation regime, showing that the maximum strain rate limitation was reached long before the maximum swelling rate of 1%/dpa was reached. Thus, the creep contribution was declining as the swelling rate increased throughout the irradiation.