SIMULATION OF 1ST WALL DAMAGE - EFFECTS OF THE METHOD OF GAS IMPLANTATION

Cavity formation in an austenitic alloy related to type 316 stainless steel has been explored with regard to various methods of gas implantation. Irradiations were conducted at 900 K to doses of 1, 10, and 70 dpa with helium injection levels of 20 at. ppm/dpa. Highest swelling (18%) was exhibited by the unimplanted reference material; a lesser amount by simultaneous helium injection (11%). Greatly reduced swelling due to profuse cavity nucleation was the result of the preinjection of 1400 at. ppm He, either at room temperature (S = 1%) or at 900 K (4%). The dislocation density was not sensitive to the helium injection technique; however, the evolution of the dislocation structure from faulted loops to network was retarded for the case of RT-preinjection compared with the alternate techniques. Simultaneous injection of 50 at. ppm H/dpa, along with the helium, may have caused a modest increase in the cavity and dislocation concentrations at higher doses. © 1979.