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Teshigawara, Makoto; Ikeda, Yujiro*; Yan, M.*; Muramatsu, Kazuo*; Sutani, Koichi*; Fukuzumi, Masafumi*; Noda, Yohei*; Koizumi, Satoshi*; Saruta, Koichi; Otake, Yoshie*
Nanomaterials (Internet), 13(1), p.76_1 - 76_9, 2023/01
Times Cited Count:4 Percentile:52.62(Chemistry, Multidisciplinary)To enhance neutron intensity below cold neutrons, it is proposed that nanosized graphene aggregation could facilitate neutron coherent scattering under particle size conditions similar to nanodiamond. It might also be possible to use it in high neutron radiation conditions due to graphene's strong sp2 bonds. Using the RIKEN accelerator-driven compact neutron source and iMATERIA at J-PARC, we performed neutron measurement experiments, total neutron cross-section, and small-angle neutron scattering on nanosized graphene aggregation. The measured data revealed, for the first time, that nanosized graphene aggregation increased the total cross-sections and small-angle scattering in the cold neutron energy region, most likely due to coherent scattering, resulting in higher neutron intensities, similar to nanodiamond.
Ishitsuka, Etsuo; Sakamoto, Naoki*
Physical Sciences and Technology, 6(2), p.60 - 63, 2019/12
Tritium release into the primary coolant of the research and test reactors during operation had been studied, and it is found that the recoil release from chain reaction of Be is dominant. To reduce tritium concentration of the primary coolant, feasibility study of the tritium recoil barrier for the beryllium neutron reflectors was carried out, and the tritium recoils of various materials were calculated by PHITS. From these calculation results, it is clear that the thickness of tritium recoil barrier depends on the material and 20
40
m is required for three orders reduction.
Ishitsuka, Etsuo; Kenzhina, I.*; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*
JAEA-Technology 2018-010, 33 Pages, 2018/11
As a part of study on the mechanism of tritium release to the primary coolant in research and testing reactors, tritium recoil release rate from Li and U impurities in the neutron reflector made by beryllium, aluminum and graphite were calculated by PHITS code. On the other hand, the tritium production from Li and U impurities in beryllium neutron reflectors for JMTR and JRR-3M were calculated by MCNP6 and ORIGEN2 code. By using both results, the amount of recoiled tritium from beryllium neutron reflectors were estimated. It is clear that the amount of recoiled tritium from Li and U impurities in beryllium neutron reflectors are negligible, and 2 and 5 orders smaller than that from beryllium itself, respectively.
Teshigawara, Makoto; Harada, Masahide; Oi, Motoki; Takada, Hiroshi
Journal of Physics; Conference Series, 1021(1), p.012061_1 - 012061_4, 2018/06
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)At the spallation neutron source of J-PARC, the structural material of moderators and reflector, such as an aluminum alloy, is going to reach to the design value (20 DPA) around 2020 by an accumulation of irradiation-damage. We started the fabrication of the spare moderators and reflector in 2013 with following design of two improvements. The invar joints, such as invar-A6061 and invar- SS316L joints were newly developed to utilize them in the cryogenic multi-layered pipe with 5th annular geometry, improving the fabrication procedure much simple. The Gold-Indium-Cadmium (Au-In-Cd) as a decoupler material is also developed to reduce residual radioactivity of the used components significantly for the decoupled moderator. In this presentation, we will report these results and progress of fabrication.
Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.
Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.
Yamauchi, Michinori*; Nishitani, Takeo; Nishio, Satoshi
Denki Gakkai Rombunshi, A, 125(11), p.943 - 946, 2005/11
Considering the geometrical characteristics of tokamak reactors with low aspect ratio, a basic neutronics strategy was derived to construct the inboard structure mainly for neutron shielding and produce enough tritium in the outboard blanket. The designs for optimal inboard shield were surveyed and necessary thickness was estimated to make the neutron flux low enough on the super-conducting magnet. In addition, the outer blanket designs were studied to attain the tritium breeding ratio (TBR) large enough for a self-sustaining fusion reactor on the basis of the advanced fusion reactor materials.
Teshigawara, Makoto; Aizawa, Hideyuki; Harada, Masahide; Kinoshita, Hidetaka; Meigo, Shinichiro; Maekawa, Fujio; Kaminaga, Masanori; Kato, Takashi; Ikeda, Yujiro
JAERI-Tech 2005-029, 24 Pages, 2005/05
This report introduces the present design status of remote-handling devices for activated and used components such as moderator and reflector in a spallation neutron source of the Material and Life Science Facility (MLF) at J-PARC. The design concept and maintenance scenario are also mentioned. A key maintenance scenario adopts that the used components should be taken out from the MLF to the other storage facility after the volume reduction of them. Almost full remote handling is available to the maintenance work except for the connection/disconnection pipes of the cooling water. Total six remote handling devices are used for moderator-reflector maintenance. They are also available to the proton beam window and muon target maintenance. Maintenance scenario is separated into two works. One is to replace used components to new ones during beam-stop and the other is dispose used components during beam operation. Required period of replacement work is estimated to be 15 days, on the other hand, the disposal work is
26 days after dry up work (
30 days), respectively.
Verzilov, Y. M.; Sato, Satoshi; Nakao, Makoto*; Ochiai, Kentaro; Wada, Masayuki*; Nishitani, Takeo
JAERI-Research 2004-015, 55 Pages, 2004/10
no abstracts in English
Kai, Tetsuya; Harada, Masahide; Maekawa, Fujio; Teshigawara, Makoto; Konno, Chikara; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 41(Suppl.4), p.172 - 175, 2004/03
In J-PARC neutron source, intense protons (3 GeV,1 MW) pass through a proton-beam window and bombard a Hg target in a target-moderator-reflector-assembly (TMRA). The SS316 target chamber is the most highly activated. Decouplers (Ag-In-Cd (AIC) alloy) are also highly activated. Some neutron extraction holes of Be and AL-coated iron reflector are lined with AIC alloy. A SS316 shield is located outer the TMRA. All these components are cooled by HO or D
O. We estimated the induced-radioactivity of the TMRA components and the cooling water using NMTC/JAM, MCNP4 and DCHAIN-SP. As results, the remote maintenance and massive shields were indispensable. For example, a 30 cm thick Fe cask for the reflector assembly was necessary to attenuate the radiation less than 1 mSv/h. The cask required a 130-ton crane. The AL-coated Fe of the reflector was adopted instead of SS316 resulting in eliminating the high activity of Ni in SS316 and reduction of the cask weight. Based on these results, shielding wall designs and maintenance scenarios of the highly activated components are developed.
Fujii, Kimio; Matsuo, Hideto*
JAERI-Review 2002-034, 44 Pages, 2002/12
Graphite material is used as a moderator and reflector of graphite-moderated gas-cooled reactors such as the Tokai Nuclear Power Station of Japan Atomic Power Company. For the decommissioning of those reactors, it is very important to obtain the density of carbon-14 in the graphite of which half-time is very long, and the development of the reduction technique for density of carbon-14 is one of the main technical issues as well. The reactor ceased the commercial operation on March 1998, and is in the process of the decommissioning. Technical developement on nuclear graphite disposal is one of the main issues, and it is pointed out that carbon-14 density is an impotant factor for the treatment on the disposal of the nuclear graphite. In order to resolve the problem, literatures survey was carried out for describing the status of technical development on resolving the problem. This report describes the outline of the literatures surveyed and the list of the related literatures is attached as well.
Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 39(8), p.827 - 837, 2002/08
Times Cited Count:19 Percentile:74.14(Nuclear Science & Technology)For a decoupled hydrogen (super critical) moderator, optimization studies have been performed on a premoderator and reflector material (Pb, Be, Fe and Hg) together with the decoupling energy to realize a higher neutronic performance. The result indicated that the best neutronic performance could be obtained for a decoupled H moderator in a Pb reflector by optimizing the premoderator and adopting an appropriate decoupling energy, even compared with optimized one in a Be reflector.
Nakashima, Hiroshi; Takada, Hiroshi; Kasugai, Yoshimi; Meigo, Shinichiro; Maekawa, Fujio; Kai, Tetsuya; Konno, Chikara; Ikeda, Yujiro; Oyama, Yukio; Watanabe, Noboru; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.1155 - 1160, 2002/08
no abstracts in English
Kai, Tetsuya; Teshigawara, Makoto; Watanabe, Noboru; Harada, Masahide; Sakata, Hideaki*; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 39(2), p.120 - 128, 2002/02
Times Cited Count:13 Percentile:62.64(Nuclear Science & Technology)no abstracts in English
Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro
JAERI-Research 2001-016, 32 Pages, 2001/03
An optimization study on the premoderator, the reflector material choice and a length of the liner is carried out for the design of high performance decoupled hydrogen moderator. NMTC/JAM and MCNP-4C are used for the neutronics calculation. The result indicates that, assuming premoderator dimensions and decoupling energy is controlled, the decoupled hydrogen moderator with a premoderator can provide better pulse characteristics than that without the premoderator for a Be reflector. On the selection of the reflector material, it is clearly shown that Pb and Hg reflectors give merits in using the premoderator for higher intensity and reduction of energy deposition in moderator. It is also shown that a H2O premoderator provides a short tail while a D2O premoderator provides the high peak intensity. Minimum liner length is evaluated to be 20 cm from the viewpoint of neutronics.
Kasugai, Yoshimi; Takada, Hiroshi; Meigo, Shinichiro; Maekawa, Fujio; Nakashima, Hiroshi; Ikeda, Yujiro; Ino, Takashi*; Sato, Setsuo*; Jerde, E.*; Glasgow, D.*
JAERI-Data/Code 2000-042, 62 Pages, 2001/02
no abstracts in English
Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro
JAERI-Research 2000-014, p.40 - 0, 2000/03
no abstracts in English
Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Harada, Masahide; Sakata, Hideaki*; Ikeda, Yujiro; Kaminaga, Masanori; Hino, Ryutaro; Oyama, Yukio
Proceedings of 8th International Conference on Nuclear Engineering (ICONE-8) (CD-ROM), p.12 - 0, 2000/00
no abstracts in English
; Katakura, Junichi
JAERI-Tech 99-033, 17 Pages, 1999/03
no abstracts in English
Teshigawara, Makoto*; Watanabe, Noboru*; Takada, Hiroshi; Kai, Tetsuya; Nakashima, Hiroshi; ; Oyama, Yukio; Ikeda, Yujiro; Kosako, Kazuaki*
JAERI-Research 99-020, 33 Pages, 1999/03
no abstracts in English
; ;
JAERI-Tech 98-052, 69 Pages, 1998/11
no abstracts in English