Simultaneous effects of dissolved oxygen and applied stress on surface morphology of steels for cooling systems of blanket module in pressurized water

•The effects of dissolved oxygen and applied stress on surface morphology of F82H and SUS316 L by the pressurized water immersion test are reported.•The oxide layer of F82H sample was consisted of the outer layer of Fe oxide and the inner layer of Fe and Cr oxides layer.•In case of F82H, the Fe2O3 oxide contents within the oxide layer of sample in 100 ppb were more than that of sample in 10 ppb.•As effect of applied stress, in both F82H and SUS316 L, no significant difference was observed by applied bending stress in this test condition. A water-cooled ceramic breeder blanket system is the Japanese promising design, and the candidate structural material is a reduced activation ferritic/martensitic steel, F82H. On the other hands, the material of the pipes of cooling system is planned to an austenitic stainless steel, SUS316 L. The cooling water will commonly flow both F82H cooling channels and SUS316 L cooling pipes. Appropriate water chemistry condition for each of them is different, but it is necessary to find out a reasonable and common water chemistry condition for both of them. In the fusion blanket, since the cooling water will be irradiated by neutrons and brought about the radiolysis of water, the dissolved oxygen concentration of the cooling water is considered to change by the radiolysis of water. This research provides the simultaneous effects of dissolved oxygen and applied stress on surface morphology of F82H and SUS316 L by the pressurized water immersion test in dissolved oxygen concentration up to 100 ppb.