Oikawa, Kenichi; Sato, Hirotaka*; Watanabe, Kenichi*; Su, Y. H.; Shinohara, Takenao; Kai, Tetsuya; Kiyanagi, Yoshiaki*; Hasemi, Hiroyuki
Journal of Physics; Conference Series, 2605, p.012013_1 - 012013_6, 2023/10
Machida, Masahiko; Yamada, Susumu; Kim, M.; Okumura, Masahiko; Miyamura, Hiroko; Shikaze, Yoshiaki; Sato, Tomoki*; Numata, Yoshiaki*; Tobita, Yasuhiro*; Yamaguchi, Takashi; et al.
RIST News, (69), p.2 - 18, 2023/09
The contamination of radioactive materials leaked from the reactor has resulted in numerous hot spots in the Fukushima Daiichi Nuclear Power Station (1F) building, posing obstacles to its decommissioning. In order to solve this problem, JAEA has conducted research and development of the digital technique for inverse estimation of radiation source distribution and countermeasures against the estimated source in virtual space for two years from 2021 based on the subsidy program "Project of Decommissioning and Contaminated Water Management" performed by the funds from the Ministry of Economy, Trade and Industry. In this article, we introduce the results of the project and the plan of the renewal project started in April 2023. For the former project, we report the derivative method for LASSO method considering the complex structure inside the building and the character of the source and show the result of the inverse estimation using the method in the real reactor building. Moreover, we explain the platform software "3D-ADRES-Indoor" which integrates these achievements. Finally, we introduce the plan of the latter project.
Shimamura, Kazutoshi*; Wajima, Hiroki*; Makino, Hayato*; Abe, Satoshi*; Haga, Yoshinori; Sato, Yoshiaki*; Kawae, Tatsuya*; Yoshida, Yasuo*
Japanese Journal of Applied Physics, 61(5), p.056502_1 - 056502_7, 2022/05
Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y. H.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.
Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04
Oikawa, Kenichi; Kiyanagi, Yoshiaki*; Sato, Hirotaka*; Omae, Kazuma*; Pham, A.*; Watanabe, Kenichi*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Kai, Tetsuya; Harjo, S.; et al.
Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02
Kai, Tetsuya; Sato, Setsuo*; Hiroi, Kosuke; Su, Y.; Segawa, Mariko; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Shinohara, Takenao; Oikawa, Kenichi; et al.
Physica B; Condensed Matter, 551, p.496 - 500, 2018/12
Li, S.*; Toyoda, Masayuki*; Kobayashi, Yoshiaki*; Ito, Masayuki*; Ikeuchi, Kazuhiko*; Yoneda, Yasuhiro; Otani, Akira*; Matsumura, Daiju; Asano, Shun*; Mizuki, Junichiro*; et al.
Physica C, 555, p.45 - 53, 2018/12
-dependence of local distortions in BaFeAs and LiFeAs by X-ray PDF and XAFS methods. Although PDF data exhibit anomaly at the structure transition temperature, EXAFS data exhibit no anomaly. Data supporting the local orthorhombicity at 300 K in the tetragonal phase for BaFeAs. Arguments on the origins of the 4-fold symmetry breaking in the ground average structure of the tetragonal phase.
Sato, Hirotaka*; Shiota, Yoshinori*; Morooka, Satoshi; Todaka, Yoshikazu*; Adachi, Nozomu*; Sadamatsu, Sunao*; Oikawa, Kenichi; Harada, Masahide; Zhang, S.*; Su, Y.; et al.
Journal of Applied Crystallography, 50(6), p.1601 - 1610, 2017/12
Su, Y.; Oikawa, Kenichi; Shinohara, Takenao; Kai, Tetsuya; Hiroi, Kosuke; Harjo, S.; Kawasaki, Takuro; Gong, W.; Zhang, S. Y.*; Parker, J. D.*; et al.
Physics Procedia, 88, p.42 - 49, 2017/06
Toguri, Satohito*; Kobayashi, Shinji*; Tsuji, Masakuni*; Yahagi, Ryoji*; Yamada, Toshiko*; Matsui, Hiroya; Sato, Toshinori; Mikake, Shinichiro; Aoyagi, Yoshiaki
JAEA-Technology 2017-005, 43 Pages, 2017/03
The study on engineering technology in the Mizunami Underground Research Laboratory (MIU) project roughly consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies regarding restoration and mitigating of the excavation effect. In FY2015, as a part of the important issues on the research program, water-tight grouting method has been developed. Grouting methods utilized in the MIU were evaluated and the post-excavation grouting at the -500m Access/Research Gallery-South was planned based on these evaluation results. Also, technology development from the viewpoint of geological disposal was summarized, and information on the alternative method to the grouting method was collected and organized.
Fukaya, Masaaki*; Takeda, Nobufumi*; Miura, Norihiko*; Ishida, Tomoko*; Hata, Koji*; Uyama, Masao*; Sato, Shin*; Okuma, Fumiko*; Hayagane, Sayaka*; Matsui, Hiroya; et al.
JAEA-Technology 2016-035, 153 Pages, 2017/02
The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) project in FY2016, detailed investigations of the (mechanical) behaviors of the plug and the rock mass around the reflood tunnel through ongoing reflood test were performed as part of (5) development of technologies for restoration and/or reduction of the excavation damage. As the result, particularly for the temperature change of the plug, its analytical results agree fairly well agree with the measurement ones. This means cracks induced by temperature stress can be prevented by the cooling countermeasure works reviewed in designing stage. In addition, for the behaviors of the plug and the bedrock boundary after reflooding the reflood tunnel, comparison between the results obtained by coupled hydro-mechanical analysis (stress-fluid coupled analysis) with the ones by several measurements, concluded that the model established based on the analysis results is generally appropriated.
Oikawa, Kenichi; Su, Y.; Tomota, Yo*; Kawasaki, Takuro; Shinohara, Takenao; Kai, Tetsuya; Hiroi, Kosuke; Zhang, S.*; Parker, J. D.*; Sato, Hirotaka*; et al.
Physics Procedia, 88, p.34 - 41, 2017/00
Time of flight Bragg edge transmission (BET) imaging was adopted to the plastically bent plates of a ferritic steel and a duplex stainless steel, and the obtained results were validated using neutron diffraction method and electron backscatter diffraction (EBSD) observations. The BET imaging results of texture distribution and phase volume fractions showed good agreements with those obtained by neutron diffraction and EBSD. The crystallite size evaluation using extinction correction was succeeded by the RITS code where Sabine's primary extinction function was applied, however, the crystallite size was not obtained by the Rietveld refinement where the same function was used for the evaluation. In this study, we comparatively reinvestigate the crystallite size and the dislocation density of the plastically bent steel plates by the use of Pawley analysis on the diffraction data and grain analysis on EBSD data.
Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).
Su, Y.; Oikawa, Kenichi; Harjo, S.; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Zhang, S.*; Parker, J. D.*; Sato, Hirotaka*; et al.
Materials Science & Engineering A, 675, p.19 - 31, 2016/10
Shimaoka, Takehiro*; Kaneko, Junichi*; Sato, Yuki; Tsubota, Masakatsu*; Shimmyo, Hiroaki*; Chayahara, Akiyoshi*; Watanabe, Hideyuki*; Umezawa, Hitoshi*; Mokuno, Yoshiaki*
Physica Status Solidi (A), 213(10), p.2629 - 2633, 2016/10
Fukaya, Masaaki*; Hata, Koji*; Akiyoshi, Kenji*; Sato, Shin*; Takeda, Nobufumi*; Miura, Norihiko*; Uyama, Masao*; Kaneda, Tsutomu*; Ueda, Tadashi*; Hara, Akira*; et al.
JAEA-Technology 2016-002, 195 Pages, 2016/03
The researches on examination of the plug applied to the future reflood test was conducted as a part of (5) development of technologies for restoration and/on reduction of the excavation damage relating to the engineering technology in the MIU (2014), specifically focused on (1) plug examination (e.g. functions, structure and material) and the quality control methods and (2) analytical evaluation of rock mass behavior around the plug through the reflood test. As the result, specifications of the plug were determined. These specifications should be able to meet requirements for the safety structure and surrounding rock mass against predicted maximum water pressure, temperature stress and seismic force, and for controlling the groundwater inflow, ensuring the access into the reflood gallery and the penetration performance of measurement cable. Also preliminary knowledge regarding the rock mass behavior around the plug after flooding the reflood gallery by installed plug was obtained.
Kobayashi, Shinji*; Niimi, Katsuyuki*; Tsuji, Masakuni*; Yamada, Toshiko*; Aoyagi, Yoshiaki; Sato, Toshinori; Mikake, Shinichiro; Osawa, Hideaki
JAEA-Technology 2015-039, 170 Pages, 2016/02
The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) plan consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies regarding restoration or reversal and mitigating of the excavation effect. To develop design and construction planning technologies, and countermeasure technology, the analysis of measured data during earthquake and seismic movement characteristics at deep underground, and the examination of grouting method were carried out. For the characteristics of earthquake ground motion, measurement data obtained by seismometers installed in the Mizunami Underground Laboratory were analyzed, and the comprehensive assessment of the relationship between the measurement data and the geological condition at each depth was performed. As for "Study on grouting method at deep underground ", post grouting was carried out and evaluated based on the Construction plan in FY2013. Furthermore, target of the future R&D was proposed.
Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Segawa, Mariko; Harada, Masahide; Nakatani, Takeshi; Oi, Motoki; Aizawa, Kazuya; Sato, Hirotaka*; Kamiyama, Takashi*; et al.
Journal of Physics; Conference Series, 746, p.012007_1 - 012007_6, 2016/00
no abstracts in English
Hiraiwa, Kenichi*; Hirai, Kazuhide*; Sano, Tadashi*; Osawa, Hideaki; Sato, Toshinori; Aoyagi, Yoshiaki; Fujita, Tomoo; Aoyagi, Kazuhei; Inagaki, Daisuke*
JAEA-Technology 2015-033, 50 Pages, 2015/11
Japan Atomic Energy Agency (hereinafter referred to as JAEA) has been conducted a geoscientific research and development project at the Mizunami Underground Research Laboratory and the Horonobe Underground Research Laboratory in order to construct scientific and technological basis for geological disposal. As a collaborative research between JAEA and Tokyo Sokki Kenkyujo Co., Ltd. (hereinafter referred to as TML), we focused on the fiber-optic crack detection sensor developed by TML as a method to detect cracks in the support system that may affect the stability of rock cavern during the operation. To verify long-term safety performance of the sensor for decades, "Evaluation test of long-term durability of fiber-optic crack detection sensor and the support system" at the Mizunami Underground Research Laboratory and "Performance evaluation test of fiber-optic crack detection sensor for in-situ crack detection" at the Horonobe Underground Laboratory Research Laboratory were conducted. As the result, we understand that fiber-optic crack detection sensor is applicable measurement method to promptly detect the cracks in the support system.
Ikeuchi, Kazuhiko*; Kobayashi, Yoshiaki*; Suzukia, Kazunori*; Ito, Masayuki*; Kajimoto, Ryoichi; Bourges, P.*; Christianson, A. D.*; Nakamura, Hiroki; Machida, Masahiko; Sato, Masatoshi*
Journal of Physics; Condensed Matter, 27(46), p.465701_1 - 465701_7, 2015/11
We report the results of inelastic neutron scattering measurements on particular phonons of a superconducting (SC) CaPtAs(FePtAs) with the onset transition temperature K to investigate mainly what roles orbital fluctuation plays in Cooper pairing, where we observed a slight softening of the in-plane transverse acoustic mode corresponding to the elastic constant . This softening starts at temperature well above the SC , as decreases. An anomalously strong change of the scattering intensity of in-plane optical modes was observed at the M point of the pseudo tetragonal reciprocal space in the range of 35 40 meV with decreasing from far above . Because this region mainly corresponds to the motion of Fe and As atoms in the FeAs planes, the finding presents information on the coupling between the orbital fluctuation of Fe electrons and the lattice system, useful for studying the possible roles of orbital fluctuation in the pairing mechanism and/or the appearance of the so-called nematic phase.