Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Naoe, Takashi; Wakui, Takashi; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Teshigawara, Makoto; Haga, Katsuhiro
JAEA-Technology 2023-022, 81 Pages, 2024/01
JAEA-Technology-2023-022.pdf:9.87MB
In the liquid mercury target system for the pulsed spallation neutron source of Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC), pressure waves that is generated by the high-energy proton beam injection simultaneously with the spallation reaction, resulting severe cavitation erosion damage on the interior surface of the mercury target vessel. Because the bubble of pressure wave-induced cavitation collapsing near the interior surface of the mercury target vessel with applying the large amplitude of localized impact on the surface. Since the wall thickness of the beam entrance portion of the target vessel is designed to be 3 mm to reduce thermal stress due to the internal heating, the erosion damage has the possibility to cause the vessel fatigue failure and mercury leakage originated from erosion pits during operation. To reduce the erosion damage by cavitation, a technique of gas microbubble injection into the mercury for pressure wave mitigation, and double-walled structure of the beam window of the target vessel has been applied. A specimen was cut from the beam window of the used mercury target vessel in order to investigate the effect of the damage mitigation technologies on the vessel, and to reflect the consideration of operation condition for the next target. We have observed cavitation damage on interior surface of the used mercury target vessel by cutting out the disk shape specimens. Damage morphology and depth of damaged surface were evaluated and correlation between the damage depth and operational condition was examined. The result showed that the erosion damage by cavitation is extremely reduced by injecting gas microbubbles and the damage not formed inside narrow channel of the double-walled structure for relatively high-power operated target vessels.
Sato, Hisashi*; Sawada, Atsushi; Takayama, Yusuke
JAEA-Research 2020-012, 37 Pages, 2020/11
JAEA-Research-2020-012.pdf:2.66MB
JAEA-Research-2020-012-appendix(DVD-ROM).zip:468.23MB
In the safety assessment of the geological disposal of high-level radioactive waste, it is important to fully understand the permeability and mass transport properties of actual fractures when setting parameters for permeability and mass transport properties of fractures. Permeability and mass transport properties of a fracture are affected by the void structure of the fracture. Therefore, it is necessary not only to conduct a hydraulic test but also to evaluate hydraulic properties based on the void structure of the fracture. Therefore, the purpose of this study is to develop a technique to acquire a three-dimensional void structure of a fracture from fracture surface shape data, and to obtain a dataset of three- dimensional void structure data and hydraulic data of the fracture. Specifically, we made a transparent replica sample of fracture and measure the fracture surface shape data in the exact coordinates. The three-dimensional void structure data was constituted from fracture surface shape data in the same coordinates. In addition, we conducted a permeability test and tracer test for the same sample to obtain a permeability and mass transport properties of the fracture. To assess the validity of the acquired data, we compared it with the apertures evaluated based on different methods. As a result, the average aperture from the fracture void structure was almost same as the average aperture acquired by different methods, from the above that the test result was validated.
Tanigawa, Hiroyasu; Sakasegawa, Hideo*; Hashimoto, Naoyuki*; Zinkle, S. J.*; Klueh, R. L.*; Koyama, Akira*
Fusion Materials Semiannual Progress Report for the Period Ending (DOE/ER-0313/35), p.33 - 36, 2004/04
Extraction replica samples were prepared from F82H-IEA, F82H HT2, JLF-1 and ORNL9Cr to analyze the precipitate distribution. The samples were examined to obtain precipitate size distribution with TEM and to analyze chemical composition distribution with SEM. Back-scattered electron imaging was found to be the effective way to separate Ta-rich precipitate from other precipitates. Results showed that most of the precipitates were M23C6, and the shape is a round ellipsoid in F82H-IEA and HT2, but was a long ellipsoid in JFL-1 and ORNL9Cr. It was also found that MX precipitates were few and large and contain Ti in F82H-IEA and HT2, but a lot of fine MX precipitates without Ti were observed in JLF-1 and ORNL9Cr.
Kikuchi, Kenji; Kaji, Yoshiyuki
Zairyo, 44(505), p.1244 - 1248, 1995/10
no abstracts in English
