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

A water-cooled ceramic breeder blanket system is the Japanese promising design, and the candidate structuralmaterial is a reduced activation ferritic/martensitic steel, F82H. On the other hands, the material of the pipes ofcooling system is planned to an austenitic stainless steel, SUS316 L. The cooling water will commonlyflow bothF82H cooling channels and SUS316 L cooling pipes. Appropriate water chemistry condition for each of them isdifferent, but it is necessary tofind out a reasonable and common water chemistry condition for both of them. Inthe fusion blanket, since the cooling water will be irradiated by neutrons and brought about the radiolysis ofwater, the dissolved oxygen concentration of the cooling water is considered to change by the radiolysis ofwater. This research provides the simultaneous effects of dissolved oxygen and applied stress on surface mor-phology of F82H and SUS316 L by the pressurized water immersion test in dissolved oxygen concentration up to100 ppb.