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Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Kuwabara, Kazumichi; Takayama, Yusuke
JAEA-Research 2015-025, 31 Pages, 2016/03
JAEA-Research-2015-025.pdf:13.0MB
It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior. On the other hand, it was revealed that the chemical reaction of groundwater in a rock had an influence on the long-term behavior. An evaluation of the microcracks to have an influence on these mechanical and chemical coupled phenomena should be worked on chiefly. In fiscal year 2014, this study performed numerical analysis to examine the supersonic scattering attenuation decrement behavior in the crystalline rock and a measurement sequentially last year. The measurement of the head and surface waves were carried out. As a result, group speed was provided. On the other hand, the spread scattering analysis of the elastic wave by the FDTD (Finite Difference Time-Domain) method made a numerical analysis. However, a laboratory finding is different from expectation of the simulation, and crystal anisotropic influence of a microcrack and rock-forming minerals is thought about as a cause of this estrangement. Therefore it was revealed that it was necessary to examine these two points of influence more in future.
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi
JAEA-Research 2014-027, 25 Pages, 2015/02
JAEA-Research-2014-027.pdf:16.92MB
The rock and the rock mass are known to show time-dependent behavior such as creep and the stress-relaxation. It is to evaluate long-term rock mechanics stability that the important theme understanding the property. From the research study until now, it is rock mechanics and chemical coupled phenomenon to have an influence on the long-term behavior. It is a theme to develop technique to model this coupled phenomenon, and to analyze. About an evaluation of the microcrack to have an influence on this coupled phenomenon, it is the theme that we should work on in a long-term rock mass behavior study chiefly. This study developed numerical analysis to check the ultrasonic scattering decrement behavior by the microcrack of the crystalline rock and the measurement technique. The FDTD method which modelled a crack was used for numerical analysis by split node. It depends on the simulation technique that it developed that useful knowledge was provided by elastic wave modeling. On the other hand, the ultrasonic measurement in a rock sample was measured by the water immersion method. As a result, we understood that we could acquire useful information to evaluate the scattering decrement of an elastic wave in a rock sample.
Moriyama, Shinichi; Kimura, Haruyuki; Fujii, Tsuneyuki; Saigusa, Mikio*; Arai, H.*
Japanese Journal of Applied Physics, 37(6A), p.3536 - 3540, 1998/06
Times Cited Count：4 Percentile：23.96(Physics, Applied)no abstracts in English
Moriyama, Shinichi; Kimura, Haruyuki; Saigusa, Mikio; Fujii, Tsuneyuki; *; *; *; *
Fusion Engineering and Design, 39-40, p.135 - 142, 1998/00
no abstracts in English
Segawa, Tomoomi; Tanigawa, Masafumi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Kitazawa, Toshihide*; Kashiwa, Tatsuya*
no journal, ,
To improve the handling and sinterability of raw powder of a uranium and plutonium mixed oxide produced in the reprocessing process of spent fuels, the microwave heating equipment has been developed considering the microwave property of linear polarization and circularly polarization that contribute to the uniformization of the microwave heating denitration by JAEA. The electromagnetic field simulation analysis was carried out by the Finite-Difference Time-Domain method, and the experimental results were evaluated. An analysis model was developed based on the obtained physical property data which were measured by the cylindrical cavity resonator method. The liquid phase state, microwave was concentrated on the upper surface and bottom surface due to the high loss of the cobalt nitrate aqueous solution, while in the solid phase state, microwave energy was absorbed inside. The absorption electric power distribution became uniform in the circumferential direction.
