Material development in lead-bismuth spallation target system

Kikuchi, Kenji; Saito, Shigeru   ; Hamaguchi, Dai; Tezuka, Masao; Obayashi, Hironari  

R&Ds to know materials performance and its limit for usage applying to the beam window of ADS are conducted by irradiation material test and lead bismuth flowing loop tests. Proton irradiation experiment showed ductility reduction and off-set stress increase in austenitic steels. Fracture mode change in ferritic-martensitic steels, 8-9 Cr steels. Fatigue test is under way in the hot cell. Microstructure analyses found that many bubbles exist in the materials. The relation between mechanical strength and nano-scale observation results is studied now. Corrosion of the materials under the lead bismuth flows showed local erosion-corrosion. A visualization technique has developed by using ultrasonic Doppler method and surface vitalizing techniques to inspect a local flow condition. Thermal fluid experiment was conducted to know heat transfer performance at the beam window, which will affect thermal loading magnitude. Experimental formula was established for design work.