Neutron-induced swelling of commercial alloys at very high exposures

Density change measurements have been completed on a wide variety of commercially available structural alloys irradiated to neutron fluence levels as large as 2.8 /times/ 1023 n/cm2 (E > 0.1 MeV) or /approximately/140 dpa in EBR-II at eight temperatures between 399 and 650/degree/C. While there was essentially no swelling in some ferritic alloys and some austenitic superalloys, other austenitic alloys exhibited a wide range of swelling depending on composition, heat treatment and irradiation temperature. The swelling behavior of the austenitic alloy system is shown to reflect primarily the influence of the overall composition and the irradiation temperature on the duration of the transient regime of void swelling, and secondarily to reflect the influence of precipitation and cold work. 16 refs., 6 figs., 5 tabs