Lifetime prediction of the neutron target vessel

Naoe, Takashi   ; Kogawa, Hiroyuki  ; Wakui, Takashi  ; Haga, Katsuhiro  

Mercury target vessel installed in the J-PARC is damaged by the proton and neutron irradiation, fatigue and cavitation erosion induced by pressure waves. The erosion damage on the beam window is particularly reducing the structural integrity of the target vessel and obstacle to realize the long-term operation with high power. As the damage mitigation techniques to reduce erosion damage, gas microbubble injection into mercury, and double-walled beam window structure has been installed. The effect of these techniques on the interior surface damage of the target vessel has been validated through the damage inspection, and gradually ramping-up the beam power. The index for considering the operational beam power, the empirical equation to predict the erosion depth of the target vessel has been developed based on the off-beam experiment and measured depth of the used target vessel. In the presentation, the lifetime of the target vessel predicted from empirical equation will be discussed.