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Sanada, Yukihisa; Misono, Toshiharu; Shiribiki, Takehiko*
Kaiyo Riko Gakkai-Shi, 27(2), p.37 - 44, 2023/12
This paper summarizes the general situation of marine monitoring conducted after the Fukushima Daiichi Nuclear Power Plant accident, the experience of development and operation of USVs, and the possibility of applying unmanned vessels as a tool for nuclear disaster prevention in the future. 0.01 Bq/L or less for seawater and 10 Bq/L or less for seabed soil. Operational tests of three USVs have been continuously conducted for use in such environmental radiation monitoring. Development of these UAVs is underway with a view to utilizing them for seawater sampling, direct measurement of the seafloor soil surface layer, and seafloor soil sampling, depending on their performance. It is necessary to promote the development of USVs for future nuclear power plant accidents.
Murakami, Hiroaki; Nishiyama, Nariaki; Takeuchi, Ryuji; Iwatsuki, Teruki
Oyo Chishitsu, 64(2), p.60 - 69, 2023/06
In order to confirm the quality control items for borehole closure in radioactive waste disposal projects, in-situ borehole sealing tests using bentonite material were conducted. As a result, the closure performance was successfully demonstrated by comparing the data of water injection tests conducted before and after the installation of the closure material. However, the breakthrough was observed after closing, probably due to high differential pressure applied to the seal section. Thus, it is important to ascertain throughout the entire operation that the borehole is adequately closed. The placement and specifications of the closure material should be determined according to the hydrogeological structure in the borehole. The confirmation items to use bentonite for sealing material are identified to be: to consider swelling and density loss in the borehole; to place the planned depth using appropriate emplacement technique; to be placed without damage to seals when use some backfilling materials, considering effect of permeability on adjacent seals.
Takayama, Yusuke
International Journal of Rock Mechanics and Mining Sciences, 136, p.104538_1 - 104538_8, 2020/12
Times Cited Count：3 Percentile：24.61(Engineering, Geological)It is necessary to apply reliable numerical simulation techniques to assess the mechanical behaviour of repositories for the geological disposal of radioactive waste over a long period of time. Having a constitutive model that can describe the mechanical behaviour of bentonite is key to such numerical simulations. In this study, the applicability of linear elastic constitutive model with swelling term is examined focusing on the density heterogeneity by applying to the in situ Full-scale Engineered Barrier Experiment (FEBEX) in Grimsel. It was confirmed that this constitutive model underestimates the density change. Instead, mechanical behaviour was re-simulated by unsaturated elasto-plastic constitutive model using the changes in degree of saturation as input data. Although no feedback effects of mechanical behaviour on hydraulic and thermal behaviour were taken into account, two-dimensional stress and density could be reproduced.
Nakayama, Masashi; Ono, Hirokazu; Nakayama, Mariko*; Kobayashi, Masato*
JAEA-Data/Code 2019-003, 57 Pages, 2019/03
JAEA-Data-Code-2019-003.pdf:18.12MB
JAEA-Data-Code-2019-003-appendix(CD-ROM).zip:99.74MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, Geoscientific Research and Research and Development on Geological Disposal Technologies, and proceeds in 3 overlapping phases, Phase I: Surface-based investigations, Phase II: Investigations during tunnel excavation and Phase III: Investigations in the URL, over a period of around 20 years. Phase III investigation was started in 2010 FY. The in-situ experiment for performance confirmation of engineered barrier system had been prepared from 2013 to 2014 FY at GL-350 m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with THMC coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the experiment from December, 2014 to March, 2018. The summarized data of the EBS experiment will be published periodically.
Hayashi, Naoki; Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1055 - 1059, 2018/08
The J-PARC Rapid-Cycling Synchrotron (RCS) is designed as an 1-MW high power accelerator. It has been operated since 2007, and its injection energy and beam current are upgraded in 2014. Its operation is very smooth and provides the high intensity beam to the Material and Life science experimental facility (MLF) and the Main Ring (MR). The beam is injected with multi-turn mode. It is possible because the negative hydrogen ion beam from the Linac, H
, and the circulating proton beam H
are different state. The H is converted to H at the injection point, where a charge stripper foil is set. A small fraction of the injected beam, which is not fully stripped, are transferred to the injection beam dump through H0 dump line to prevent un-necessary activation. Since the limit of beam dump is only 4 kW, which is about 3% of designed injection beam power 133 kW, the beam has to be stopped immediately in case of stripper foil break up incident.
Hayashi, Naoki; Saha, P. K.; Yoshimoto, Masahiro; Miura, Akihiko
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.277 - 280, 2017/06
Multi-turn painting injection scheme is important for high intensity proton accelerators. At the J-PARC RCS, a transverse painting scheme was adapted by adding vertical painting magnets to the beam transport line before the injection point, with horizontal painting being performed by a set of dedicated pulse magnets in the ring. To establish a transverse painting condition, it is usual to base on the pulse magnet current pattern. However, it is more desirable to directly measure the beam orbit time variation for evaluation. A linac beam was chopped to match the ring RF bucket. We thought that it would be difficult to measure the position for each pulse; however, the average position could be extracted by introducing a particular device. For the beam injected into the ring, because the linac RF frequency component was diminished due to debunching quickly, one could determine its position in the beginning of the injection period. However, due to rebunching effect the position determination becomes difficult. This problem needs to be resolved.
Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru
Hamon, 27(1), p.4 - 7, 2017/01
Development of scintillation neutron detectors using wavelength-shifting fiber (WLSF) technology at J-PARC MLF is briefly reviewed. The neutron-detecting head of this type detector comprises neutron-sensitive scintillator screens and WLSFs for light read out. The light collection using WLSFs enables us to design a detector with great flexibility. Detector specifications such as pixel size, spatial resolution, and neutron-sensitive area can be optimized to requirements in specific applications. We have intensively developed these detectors since 2005. A large number of detector modules have been produced and delivered to the neutron scattering instruments in the MLF. In this paper the design of SENJU detector is presented in detail together with recent development effort for detector technology alternative to helium-3 gas detectors.
Morishita, Takatoshi
JPS Conference Proceedings (Internet), 8, p.011006_1 - 011006_6, 2015/09
The displacement of the accelerator components induces the beam losses so that the alignment is important for the stable beam operation. The stability of the floor height became worth after the Tohoku earthquake in March 11th, 2011. The floor height is affected by the environmental conditions such as weather, earthquake, and so on. The degrees of these movements are identified by the monitoring system. By the usual earthquake, the deformation seems random and negligibly small. The heavy rain tilts the floor, however, which recovered gradually. The significant vertical deformation was observed by the long-term monitoring for more than months. Degree of this deformation is comparable to the surveyed results. Then, the slow movement dominates the vertical deformation of the J-PARC linac tunnel floor.
, Na, I and HTO in granodiorite; Laboratory-scale results and their extrapolation to the in situ conditionTachi, Yukio; Ebina, Takanori*; Takeda, Chizuko*; Saito, Toshihiko*; Takahashi, Hiroaki*; Ouchi, Yuji*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.10 - 24, 2015/08
Times Cited Count：29 Percentile：74.23(Environmental Sciences)Matrix diffusion and sorption are important processes in the assessment of radionuclide transport in crystalline rocks. Diffusion and sorption parameters for Cs, Na, I and HTO were determined by through-diffusion and batch sorption experiments using granodiorite samples from the Grimsel Test Site, Switzerland. The De values were in the order Cs, Na, HTO, I. The capacity factor and Kd values show the same trends. The dual depth profiles for Cs and Na can be interpreted by a near-surface Kd increment. The microscopic analysis indicated that this is caused by high porosity and sorption capacities in disturbed biotite minerals on the sample surface. The Kd values derived from the dual profiles are likely to correspond to Kd dependence on the grain sizes of crushed samples in the batch experiments. The results of the in situ LTD experiments were interpreted reasonably well by using transport parameters derived from laboratory data and extrapolating them to in situ conditions.
Kurihara, Kenichi; Itagaki, Masafumi*; Miyata, Yoshiaki; Nakamura, Kazuo*; Urano, Hajime
Purazuma, Kaku Yugo Gakkai-Shi, 91(1), p.10 - 47, 2015/01
no abstracts in English
Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki*; Yonekawa, Izuru; Suzuki, Takahiro; Oikawa, Toshihiro; Ide, Shunsuke; JT-60 Team
Fusion Engineering and Design, 74(1-4), p.527 - 536, 2005/11
Times Cited Count：11 Percentile：59.86(Nuclear Science & Technology)Since tokamak magnetic fusion research has just made a step forward to an international collaborative project ITER, the existing tokamaks including JT-60 are expected to explore more advanced operation scenarios. To test those scenarios in the JT-60 experiment, the basic methods for understanding of plasma equilibrium have been developed. Some of them have been accomplished, and the other are being conducted as follows: (1) A complete plasma shape is precisely reproduced in real time. (2) Eddy current effects are considered for shape reproduction. (3) A plasma current profile in the poloidal cross-section is reproduced in real. (4) For long-pulse DT operation, a method is developed to correct the drifted signal of the integrator for a pick-up coil by employing distant sensor signals. In the symposium, those methods will be explained in detail with the experimental results at JT-60. On the basis of such discussion, we would like to envisage a future of plasma equilibrium control toward ITER and a fusion power plant.
Ebine, Masumi; Katagiri, Masaki; Birumachi, Atsushi; Matsubayashi, Masahito; Sakasai, Kaoru; Sato, Setsuo*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.429 - 432, 2004/08
Times Cited Count：1 Percentile：10.27(Instruments & Instrumentation)no abstracts in English
Katagiri, Masaki; Matsubayashi, Masahito; Sakasai, Kaoru; Nakamura, Tatsuya; Ebine, Masumi; Birumachi, Atsushi; Rhodes, N.*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.313 - 316, 2004/08
Times Cited Count：13 Percentile：63.86(Instruments & Instrumentation)no abstracts in English
resonance in the relativistic approachMaruyama, Tomoyuki*; Chiba, Satoshi
Progress of Theoretical Physics, 111(2), p.229 - 243, 2004/02
no abstracts in English
Agui, Akane; Aoyagi, Hideki*; Yoshigoe, Akitaka; Nakatani, Takeshi
JAERI-Tech 2003-089, 23 Pages, 2003/12
JAERI-Tech-2003-089.pdf:1.33MB
no abstracts in English
Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Takahashi, Hiroyuki*; Nakazawa, Masaharu*
Nuclear Instruments and Methods in Physics Research A, 513(1-2), p.374 - 378, 2003/11
Times Cited Count：3 Percentile：27.66(Instruments & Instrumentation)no abstracts in English
To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*
Applied Physics A, 74(Suppl.1), p.S1601 - S1603, 2002/12
Times Cited Count：6 Percentile：28.31(Materials Science, Multidisciplinary)no abstracts in English
Katagiri, Masaki; To, Kentaro; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*
Applied Physics A, 74(Suppl.1), p.S1604 - S1606, 2002/12
Times Cited Count：6 Percentile：28.31(Materials Science, Multidisciplinary)no abstracts in English
Fujimoto, Nozomu; Nojiri, Naoki; Yamashita, Kiyonobu; Shimakawa, Satoshi; Ando, Hiroei; Mori, Takamasa
Nihon Genshiryoku Gakkai Monte Karuro Ho Ni Yoru Ryushi Shimyureshon No Genjo To Kadai, p.201 - 210, 2002/01
no abstracts in English
Toh, Yosuke; Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi; Katakura, Junichi; Matsuda, Makoto; Iimura, Hideki; Kusakari, Hideshige*; Nishimiya, Daisuke*; Sugawara, Masahiko*; et al.
Review of Scientific Instruments, 73(1), p.47 - 50, 2002/01
Times Cited Count：9 Percentile：47.85(Instruments & Instrumentation)no abstracts in English
