Effect of dose rate on the microstructure of CW 316 SS

The microstructural and microchemical changes occurring after a constant irradiation time on CW 316 irradiated at different dose rates in the high temperature range have been studied. The investigations have been performed on specimens irradiated around 6000C for 350-400 days at dose rates ranging between 3 and 22.10-7 dpaFs-1. The samples have been cut from Phenix fuel pin cladding. Two different heats have been examined, they differ essentially by the fact that at the highest dose rate investigated heat-1 has attained the steady state swelling regime whereas heat-2 is only reaching the end of the incubation dose. The samples have been examined by TEM techniques and energy dispersive X-ray analysis. Voids and dislocation structures have been investigated