Sakashita, Satoshi; Okui, Masahiro; Yoshida, Tadayoshi; Uezu, Yasuhiro; Okuda, Eiichi
JAEA-Review 2022-012, 42 Pages, 2022/06
In this report, results of investigating fire alarm detectors status in order to understand the actual situation of false alarm occurrence and measures to systematically update of them. Based on results of this investigation, measures to systematically update of detectors were taken in order to reduce false fire alarm reports in a harsh environment and aged detectors. Numbers of detectors, false alarms were investigated. Furthermore, causes of their occurrence were investigated for three years (2018-2020). As a result of this investigation, it was found that most of the 34,400 fire alarm detectors in JAEA have been used for more than 20 years. In the last 3 years, 65 false alarms have been reported, 60% of which were found to have been used where the environment should be improved. It was also found that there are many cases where false alarms are reported from a detector within 14 years after installation. Based on the above, three basic policies were formulated. First of all, database will be built for fire alarm maintenance and inspection, secondly, installation location of fire alarm will be improved, and finally, detectors will be updated with reference to the manufacture's plan. According to the three basic policies, it is considered that the reports of false fire alarms will be able to reduced.
Katsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
The structure of a neutron-rich F nucleus is investigated by a quasifree () knockout reaction. The sum of spectroscopic factors of orbital is found to be 1.0 0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 35% O, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
Kono, Yuko; Ayame, Junko; Yoshida, Tomoo*; Ikuta, Yuko; Kawase, Keiichi; Yamashita, Kiyonobu
JAEA-Review 2018-007, 36 Pages, 2018/06
English translation of the material used at "Meeting to Answer Questions on Radiation" was made. "Meeting to Answer Questions on Radiation" was planned, just after the TEPCO Fukushima Daiichi Nuclear Power Plant Accident, by Japan Atomic Energy Agency (JAEA) with the purpose of providing comprehensive knowledge of radiation to the public. A total of 220 meetings was carried out from July, 2011 to February, 2013 mainly in Fukushima prefecture. Since the material used in the meetings contains many charts and is easy to understand, it has drawn attention of the International Atomic Energy Agency (IAEA) who has in recent years actively supported outreach activities to disseminate knowledge on nuclear and radiation. At one of the IAEA meetings in May, 2017, Asian Network for Education in Nuclear Technology (ANENT), it was requested to make it for the usage of all. Providing IAEA and the member states with the English translation of the material will be a meaningful contribution sharing the outreach activity experiences in Japan.
Watanabe, Masahisa; Tagawa, Akihiro; Umemiya, Noriko; Maruyama, Noboru; Yoshida, Mami; Kawase, Keiichi; Noguchi, Shinichi; Sakazume, Yoshinori; Watanabe, Masanori; Hiraga, Hayato; et al.
JAEA-Review 2014-028, 184 Pages, 2014/10
JAEA received technical proposals from private enterprise about techniques that can be used for decontamination work, and "Decontamination Technology Demonstrations Projects" was commissioned from the Ministry of the Environment to verifies the decontamination effect, economy feasibility, safety, and other factors. By the "FY 2013 Decontamination Technology Demonstrations Projects" JAEA carried out technical advice of demonstration test and evaluation of 11 technologies (e.g., decontamination of soils and green space and wastes and washing of fly ash).
JAEA-Review 2013-026, 151 Pages, 2013/12
Corrosion research of the materials in high temperature sodium was done since 1960's in U.S., Europe, Russia and Japan for the development of sodium-cooled fast reactors, and the many excellent results were obtained. In Japan, various equipment was designed and manufactured to establish the material-testing technologies and to develop the sodium environmental effect methods. Up to present, the R&D examinations in sodium were performed using the equipment, and many experience and knowledge were obtained. The results were reflected to the experimental reactor "Joyo", the prototype nuclear reactor "Monju" and the R&D for commercial fast reactors. In this report, the sodium technology in the field of material research and the effect of sodium on material properties were reviewed based on author's experience and knowledge. Author hopes that the report is reflected to the future R&D and the technical succession for engineers.
Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03
Yoshida, Eiichi; Kato, Shoichi; Furukawa, Tomohiro
JAEA-Research 2012-034, 68 Pages, 2013/01
Oxygen concentration in sodium is the important factor for the corrosion of FBR structural materials. In this study, the experiments have been done to clarify the effect of sodium contaminated by oxygen on corrosion and low cycle fatigue strength of the materials. The materials for use of the experiments were FBR Grade type 316 SS (316FR) and Mod. 9Cr-1Mo steel. The corrosion test has been performed in sodium containing of 1, 10 and 10 ppm of initial oxygen at 650C for 500 hours. The fatigue test has been done for the post-immersed steels at 650C in air.
Yoshida, Eiichi; Hirakawa, Yasushi; Yatabe, Toshio
JAEA-Technology 2012-033, 177 Pages, 2012/11
In JAEA, lots of tests using sodium had been carried out on the development of sodium component systems and sodium technologies for the experimental reactor JOYO and prototype reactor MONJU. When research and development has come to the end of the first stage for these reactors, those sodium test facilities has dismantled and attached sodium has been cleaned. Lots of experiences and knowledge of sodium cleaning treatment technologies has accumulated. In order to use those experiences and knowledge effectively for future sodium technology and research on the next generation fast reactors, experiences and knowledge of sodium technologies for typical systems and components has been evaluated and knowledge related important topics has been rearranged. Based on those evaluation and rearrangement, technical guidelines of sodium cleaning treatment technologies has been proposed for the purpose of effective reference of the past experiences and knowledge.
Hatae, Takaki; Yoshida, Hidetsugu*; Yatsuka, Eiichi
Purazuma, Kaku Yugo Gakkai-Shi, 88(10), p.555 - 574, 2012/10
no abstracts in English
Hatae, Takaki; Yatsuka, Eiichi; Hayashi, Toshimitsu; Yoshida, Hidetsugu*; Ono, Takehiro; Kusama, Yoshinori
Review of Scientific Instruments, 83(10), p.10E344_1 - 10E344_3, 2012/10
A prototype YAG laser system for the edge Thomson scattering system in ITER has been newly developed. Performance of the laser amplifier was improved by using flow tubes made of samarium-doped glass; the small signal gain reached 20 at its maximum. As a result, an output energy of 7.66 J at 100 Hz was successfully achieved, and the performance exceeded the target performance (5 J, 100 Hz).
Shimada, Kenji*; Ueno, Hideki*; Neyens, G.*; Asahi, Koichiro*; Balabanski, D. L.*; Daugas, J. M.*; Depuydt, M.*; De Rydt, M.*; Gaudefroy, L.*; Grvy, S.*; et al.
Physics Letters B, 714(2-5), p.246 - 250, 2012/08
no abstracts in English
Furukawa, Tomohiro; Yoshida, Eiichi
Comprehensive Nuclear Materials, 5, p.327 - 341, 2012/03
This manuscript is an explanation about the compatibility of FBR materials with sodium. This will be published in the book "Comprehensive Nuclear Materials" from Elsevier in 2012. Corrosion mechanism of materials in sodium, corrosion behaviour and factors effecting steel, effect of sodium on mechanical strength of steels, damage to steels with sodium compounds and tribology are described in this manuscript.
Yoshida, Eiichi; Furukawa, Tomohiro
Nuclear Corrosion Science and Engineering, p.773 - 806, 2012/00
For sodium cooled fast reactor systems, the effect of sodium environment on corrosion and mechanical properties of the structural materials have to be evaluated to maintain the material integrity throughout the plant design life. In this paper, the effect of sodium on the mechanical strength, such as creep and fatigue, which is the dominant factor of corrosion was evaluated based on the related R&D results. Furthermore, the friction and self-welding phenomena in sodium were also described.
Kato, Shoichi; Furukawa, Tomohiro; Yoshida, Eiichi
JAEA-Research 2010-022, 37 Pages, 2010/08
It is known that the cyclic thermal stress caused by the thermal striping is occurred at the parts which the coolant of the different temperatures mixes in FBR plants, and the maximum number of cycles in the service life reaches to 10-10 cycles. So, it is important to understand experimentally the relationship between the mechanical strength and the damage mechanism in the high cycle fatigue region. This report summarizes about the results of the high cycle fatigue properties of a candidate material for FBR structures, FBR grade type 316 stainless steel (316FR).
Hatae, Takaki; Hayashi, Toshimitsu; Yatsuka, Eiichi; Kajita, Shin*; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Yahagi, Kenichi*; Shinobu, Katsuya*; Ono, Takehiro; et al.
Journal of Plasma and Fusion Research SERIES, Vol.9, p.253 - 258, 2010/08
Belloni, J.*; Crowell, R. A.*; Katsumura, Yosuke; Lin, M.; Marignier, J. L.*; Mostafavi, M.*; Muroya, Yusa*; Saeki, Akinori*; Tagawa, Seiichi*; Yoshida, Yoichi*; et al.
Recent Trends in Radiation Chemistry, p.121 - 160, 2010/05
In this review, we summarized development and application of highly time resolved spectroscopy system in order to measure radiation induced fast phenomena together with current status of the systems in the world.
Furukawa, Tomohiro; Kato, Shoichi; Yoshida, Eiichi
Journal of Nuclear Materials, 392(2), p.249 - 254, 2009/07
In order to incorporate an evaluation procedure for sodium environmental effects of core and structural materials into the elevated temperature structural design guide for fast breeder reactors (FBRs), research and development of sodium compatibility of the materials has been performing in Japan Atomic Energy Agency. This paper describes the overview of sodium compatibility of the candidate materials which are used as core and structures of Japanese demonstration FBRs.
Nakamura, Hiroo; Agostini, P.*; Ara, Kuniaki; Fukada, Satoshi*; Furuya, Kazuyuki*; Garin, P.*; Gessii, A.*; Giusti, D.*; Groeschel, F.*; Horiike, Hiroshi*; et al.
Fusion Engineering and Design, 84(2-6), p.252 - 258, 2009/06