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Harjo, S.; Kubota, Satoru*; Gong, W.*; Kawasaki, Takuro; Gao, S.*
Acta Materialia, 196, p.584 - 594, 2020/09
Times Cited Count：12 Percentile：62.56(Materials Science, Multidisciplinary)Aoyagi, Kazuhei; Tsusaka, Kimikazu; Kubota, Kenji*; Tokiwa, Tetsuya; Kondo, Keiji; Inagaki, Daisuke
Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 70(4), p.412 - 423, 2014/12
The authors have been conducting seismic and resistivity tomography surveys in a gallery of the Horonobe Underground Research Laboratory in order to investigate an extent of an excavation damaged zone (EDZ) along time. The objective of this paper is to discuss an influence of fracture distribution and water saturation of a rock mass on variations in seismic velocity and the value of apparent resistivity in an EDZ. Based on the result of seismic tomography survey, the extent of a layer which has low seismic velocity was about 1.0 m from the gallery wall after excavation of the tomography area. From the results of resistivity tomography survey, the value of apparent resistivity has not changed remarkably along time. To investigate a relationship between variations in seismic velocity and density of fracture in the survey area, the authors built a three dimensional fracture model around the tomography area. From the comparison of seismic velocity with density of fracture, seismic velocity decreased almost linearly as the density of fracture increased. Also, it was found that density of fracture in the layer of low seismic velocity could be estimated using a simple numeric model. From this result, seismic tomography survey and investigation of density of fracture are suitable method for evaluation of an EDZ.
Aoyagi, Kazuhei; Tsusaka, Kimikazu*; Nohara, Shintaro*; Kubota, Kenji*; Tokiwa, Tetsuya*; Kondo, Keiji*; Inagaki, Daisuke*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 8 Pages, 2014/10
Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12
Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.
Sato, Susumu; Tomisawa, Tetsuo; Sako, Hiroyuki; Shen, G.; Ueno, Akira; Akikawa, Hisashi*; Igarashi, Zenei*; Lee, S.*; Ikegami, Masanori*; Kamikubota, Norihiko*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.4072 - 4074, 2007/08
The beam commissioning of J-PARC LINAC has been started in November 2006. Beam Position Monitors (BPM's) which had been calibrated on the bench setup with a scanning wire, take beam-based-calibration method in order to enable the beam to pass at the centre of a quadrupole magnet (Q-magnet). The installed BPM's and their calibration methods are described.
Sato, Susumu; Tomisawa, Tetsuo; Akikawa, Hisashi; Ueno, Akira; Lee, S.*; Igarashi, Zenei*; Ikegami, Masanori*; Toyama, Takeshi*; Kamikubota, Norihiko*
Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.2777 - 2779, 2005/00
The J-PARC LINAC requires for fine control of beam position to minimize beam loss. So that BPMs need to be calibrated with the accuracy of about a hundred micro-meters. The accuracy of BPMs are calibrated with the calibration tool and real beam. In this paper, details of these developments around BPMs are to be reported.
Sato, Susumu; Tomisawa, Tetsuo; Hiroki, Fumio; Lee, S.*; Igarashi, Zenei*; Ikegami, Masanori*; Ueno, Akira; Kondo, Yasuhiro; Hasegawa, Kazuo; Toyama, Takeshi*; et al.
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.467 - 469, 2004/08
As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction. For this accelerator, it is required to minimize the beam loss (typically, lower than0.1
1 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 
m. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 stripline pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.
Sato, Susumu; Igarashi, Zenei*; Lee, S.*; Tomisawa, Tetsuo; Hiroki, Fumio; Kishiro, Junichi; Ikegami, Masanori*; Kondo, Yasuhiro; Hasegawa, Kazuo; Ueno, Akira; et al.
Proceedings of 22nd International Linear Accelerator Conference (LINAC 2004), p.429 - 431, 2004/00
As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction at Tokai, Japan. For this accelerator, it is required to minimize the beam loss (typically, lower than 0.11 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 micro-meter. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 strip-line pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.
Ijiri, Yuji*; Hattori, Hiromichi*; Suzuki, Shunichi*; Oishi, Masaya*; Kubota, Shigeru*; Adachi, Tetsuya*; Yamamoto, Takuya*
JNC TJ8400 2001-010, 143 Pages, 2001/03
JNC-TJ8400-2001-010.pdf:17.19MB
The evaluation of uncertainty of geological environment is a key issue in assessing a performance of a deep geological disposal system for high-level nuclear waste. The geological environment uncertainty is arose from data obtained from surveys and model used for a performance assessment.The objectives of this study is to develop a rational planning methodology of site characterization using the Horonobe site as a model case, and to establish a modeling methodology using the Tono site as a model case. At the Horonobe site, first, a conceptual model is constructed based on the information at every stage of site characterization procedure. A sensitivity analysis is performed using various conceptual models and data. If conceptual models uncertainty have a great impact on the result of performance assessment analysis, surveys that detect the most appropriate conceptual model are conducted in the next stage of site characterization. If data uncertainty have a great impact on the result of performance assessment analysis, surveys that decrease the data uncertainty are conducted. Thus, a rational site characterization methodology in which the most sensitive items are preferentially detected in the next stage of site characterization is developed. This concept of a rational site characterization methodology is described in this report. In addition, preliminary conceptual model is developed based on geological information around Horonobe site, and data uncertainty for the sensitivity analysis which will be conducted in next year is investigated. At the Tono site, literature on model uncertainty is surveyed, and data obtained at the Tono site is reviewed from modeling point of view.
Ijiri, Yuji*; Hattori, Hiromichi*; Suzuki, Shunichi*; Oishi, Masaya*; Kubota, Shigeru*; Adachi, Tetsuya*; Yamamoto, Takuya*; Igarashi, Takafumi*; Sugihara, Yutaka*
JNC TJ8400 2001-009, 41 Pages, 2001/03
JNC-TJ8400-2001-009.pdf:6.69MB
no abstracts in English
Anezaki, Susumu*; Sugihara, Yutaka*; Igarashi, Takafumi*; Kubota, Shigeru*; Adachi, Tetsuya*
JNC TJ1410 98-001, 74 Pages, 1998/10
As a technical problem to be solved in the underground research of sedimentary rock formation, the specification for access drift from the surface to the experimental area in the underground was studied. Considering ground condition, safety for construction and experiment execution, maintenance of experimental environment, construction period and cost, the feasibility of access drift was carried out.
Harjo, S.; Aizawa, Kazuya; Gong, W.; Kubota, Satoru*; Tomota, Yo
no journal, ,
Harjo, S.; Kubota, Satoru*; Tomota, Yo; Aizawa, Kazuya
no journal, ,
Kowatari, Munehiko; Kubota, Takumi*; Shibahara, Yuji*; Fujii, Toshiyuki*; Takamiya, Koichi*; Mizuno, Satoshi*; Yamana, Hajimu*
no journal, ,
Instead of conventional Ge semiconductor detectors and NaI(Tl) scintillation spectrometers, an application of a CZT whose crystal has the dimension of 1 cm cubic semiconductor to the in-situ environmental radio-activity measurement was attempted in deeply affected areas in Fukushima region. A CZT detector does not have such a high resolution of peaks, comparing a Ge detector. However, it is found that a CZT has enough characteristics to properly determine radio-activity of 
Cs and 
Cs in soil, throughout the in-situ measurement campaign in deeply affected area within 5 km from the Fukushima Dai-ichi Nuclear Power Plant, where dose rates exceed 50 Sv h
. Results of radioactivity concentration in soil ranged between 1 and 500 kBq m
and seem consistent to those obtained by the air-borne measurement.
Kowatari, Munehiko; Kubota, Takumi*; Shibahara, Yuji*; Fujii, Toshiyuki*; Takamiya, Koichi*; Mizuno, Satoshi*; Yamana, Hajimu*
no journal, ,
For the purpose of determining a surface deposition density on soil for radio-cesiums, a CdZnTe (CZT) semiconductor detector whose crystal has dimensions of 1 cm cubic was applied to the in situ environmental radio-activity measurement in deeply contaminated areas in Fukushima region. Even in high dose rate areas where pulse height spectra weren't able to be properly obtained by the conventional high purity Ge semiconductor detector, proper pulse height spectra were obtained by the CZT detector with certain accuracy. Results of deposition density on soil for Cs and Cs derived from net peak areas by the CZT detector seemed consistent, comparing with those measured by the Japanese government. Air kerma rates were estimated by the same pulse height spectra for determining surface deposition density on soil for radio-cesiums and found to be almost the same values as obtained by the NaI(Tl) scintillation survey-meter.
