Yuguchi, Takashi*; Usami, Akane*; Ishibashi, Masayuki
Heliyon (Internet), 6(8), p.e04815_1 - e04815_6, 2020/08
The analysis of the distribution of microfractures and micropores is important to accurately characterise mass transfer within a rock body. In this paper, a new "simultaneous polarization-fluorescence microscopy" method is presented, which can be used to analyse the distribution of microscopic voids, including microfractures and micropores, in granitic rock. In this method, thin sections prepared with fluorescent dye are analysed under a polarizing microscope equipped with a fluorescent reflected light source. Using both the transmitted and the fluorescent light sources, both the distribution of microfractures and micropores, and petrographic characteristics (mineral occurrences) can be determined efficiently and simultaneously. The distribution of microfractures and micropores observed in images of granites obtained using simultaneous polarization-fluorescence microscopy is consistent with the distribution observed in backscattered electron images.
Takeda, Toshikazu*; Usami, Shin; Fujimura, Koji*; Takakuwa, Masayuki*
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.560 - 566, 2015/09
The Ministry of Education, Culture, Sports, Science and Technology in Japan has launched a national project entitled "technology development for the environmental burden reduction" in 2013. The present study is one of the studies adopted as the national project. The objective of the study is the efficient and safe transmutation and volume reduction of minor actinides with long-lived radioactivity and high decay heat contained in high level radioactive wastes by using sodium cooled fast reactors. We are developing MA transmutation core concepts which harmonize efficient MA transmutation with core safety. To accurately design the core concepts we have improved calculation methods for estimating the transmutation rate of individual MA nuclides, and estimating and reducing uncertainty of MA transmutation. The overview of the present project is first described. The method improvement is presented with numerical results for a minor-actinide transmutation fast reactor.
Shimoyama, Kazuhito; Usami, Masayuki; Miyake, Osamu; ; ; Tanabe, Hiromi
PNC TN9450 97-007, 81 Pages, 1997/03
Shimoyama, Kazuhito; Nishimura, Masahiro; Usami, Masayuki; Miyahara, Shinya; Miyake, Osamu; Tanabe, Hiromi
PNC TN9410 97-085, 163 Pages, 1996/11
Sodium fire experiments were carried out two times using the Sodium Fire Test Rig (SOFT-1) in the Power Reactor and Nuclear Fuel Development Corp (PNC) as a part of works to research the cause of the accident in secondary main cooling system of Monju. The purposes of these experiments are to confirm the leak rate and leakage form of sodium from damaged thermometer, to confirm the damage to the piping insulating structure around the thermometer and to the flexible tube, and to compare the temperature history of the signal from the thermometer between the experiments and Monju. In the experiments 56(2)g/sec was obtained as the leak rate under the condition of ensuring the leakage pass in the simulated thermometer. This leak rate was corrected to 53g/sec to take account of manufacturing error of the theemometer between the experiment and Monju. In calculation of this leak rate, it is assumed that the annulus size of thermometer well tip is a nominal distance and pressure value to the leakage sodium is 1.65kg/cmG, which was the maximum one during the leakage of Monju. Concerning the leakage form, connection condition between the thermometer and flexiblc tube affected the dropping style of the leaking sodium especially in its initial behavior. For the connection condition of the thermometer and flexible tube at the beginning of the experiments, the first experiment was started removing the connection to simulate the post accident observation results of Monju, while the second one was started in connected condition. In the second experiment, the connection condition became to be equal with the initial state of the first experiment 17 seconds after the beginning of thc leak ; the cap nut which fixed the flexible tube to the elbow connector came off. Until the connection came off, the typical leakage form was the dispersion from the elbow connector as a droplet and the flow penetrating the covering of the flexible tube as a streamline, while after the ...
Shimoyama, Kazuhito; Hamada, Hirotsugu; Tanabe, Hiromi; Usami, Masayuki
PNC TN9410 93-212, 134 Pages, 1993/09
A one-through unit type steam generator (SG) having the Mod.9Cr-1MO Steel for its heat transfer tube is considered to be promising for the development of large FBR SGs. Wastage data of the tube material was already obtained for the micro-/small leak region as formerly reported. Therefore, intermediate leak wastage tests were conducted in the range from 10 g/s to around 200 g/s by using the SWAT-1 test facility and the test results are summarized as follows: (1)The wastage resistivity of the Mod.9Cr-1Mo steel is between that of 2.25Cr-1Mo steel and austenitic stainless steel; namely, the Mod.9Cr-1Mo steel has about half the of wastage rate of the 2.25Cr-1Mo steel. An experimental wastage formula in the intermediate leak region was derived from the test data. (2)Almost all of the wastage profile of target tubes was toroidal type and it became about half the cross section area of the 2.25Cr-1Mo steel. An experimental formula on initial leak diameters versus equivalent secondary failure diameters was derived in the intermediate leak region. These test results would be applied to failure propagation analysis code LBAP which is to be used for the design of a one-through unit type SG.
Shimoyama, Kazuhito; ; Usami, Masayuki; Tanabe, Hiromi; Yoshida, Eiichi; *
PNC TN9410 91-288, 72 Pages, 1991/07
For the development of a once-through unit type steam generator for an FBR, materials having a high mechanical strength at elevated temperatures and high resistivity against stress corrosion cracking (scc) are needed as its heat transfer tubes. High-chrome ferritic steels such as Mod.9Cr-1Mo, 9cr-2Mo, and 9Cr-1Mo-Nb-V steel are considered to meet these requirements. As previously reported, there was not large difference of resistivity among these materials and it was confirmed that high-chrome ferritic steels were more wastage -resistant than the 2.25Cr-1Mo steel which is a representative ferritic steel as tube materials. Since wastage data of weld portion at which the initial leak is apt to occur had been insufficient in order to totally evaluate the wastage resistivity of the high-chrome ferritic steels wastage tests in the micro-leak and small leak ranges were conducted for the tube-tube weld point of Mod.9Cr-1Mo steel. Major results are as follows : (1)In the micro-leak tests, there are not large differences in the self-wastage resistivity between the weld and the base metal. And the wastage resistivity is independant of the location of the leak starting point (a weld metal, a bond of weld, or a heat affected zone). (2)In the small leak tests, there are not large differences in the wastage resistivity between the weld and the base material. In the results, the empirical formula of wastage rate that derived from the base materials of the high-chrome ferritic steel can also be applied to the heat transfer tubes including the weld materials.
Mizuno, Makoto; Dairaku, Masayuki; Horiike, Hiroshi; Kitamura, Shigeru; Komata, Masao; Kuriyama, Masaaki; Matsuda, Shinzaburo; Matsuoka, Mamoru; Oga, Tokumichi; Ohara, Yoshihiro; et al.
JAERI-M 88-088, 14 Pages, 1988/05
no abstracts in English
Watanabe, Kazuhiro; Dairaku, Masayuki; ; Horiike, Hiroshi; Inoue, Takashi; Kitamura, Shigeru; Komata, Masao; Kurashima, Toru*; Mizuno, Makoto; Oga, Tokumichi; et al.
JAERI-M 88-022, 26 Pages, 1988/02
no abstracts in English
; ; ; Usami, Masayuki
PATRAM '95 (PACKAGING AND TRANSPORTATION OF RADIOACTIVE MATERIALS), ,
Uruwashi, Shinichi; ; Usami, Masayuki;
Takeda, Hideyuki; Usami, Masayuki; Hirosawa, Naonori; Fujita, Yoshihisa; Kodani, Yoshiki; Komata, Kazuhiro*
no journal, ,
no abstracts in English