Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ishii, Mamoru*; Shiota, Daiko*; Tao, Chihiro*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Ishii, Takako*; Ichimoto, Kiyoshi*; Kataoka, Ryuho*; Koga, Kiyokazu*; Kubo, Yuki*; et al.
Earth, Planets and Space (Internet), 73(1), p.108_1 - 108_20, 2021/12
Times Cited Count:8 Percentile:61.09(Geosciences, Multidisciplinary)We surveyed the relationship between the scale of space weather events and their occurrence rate in Japan and we discussed the social impact of these phenomena during the Project for Solar-Terrestrial Environment Prediction (PSTEP). The information was compiled for domestic users of space weather forecasts for appropriate preparedness against space weather disasters. This paper gives a comprehensive summary of the survey, focusing on the fields of electricity, satellite operations, communication and broadcasting, satellite positioning usage, aviation, human space activity, and daily life on the Earth's surface, using the cutting-edge knowledge of space weather. Quantitative estimations of the economic impact of space weather events on electricity and aviation are also given.
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count:6 Percentile:49.29(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
Hayakawa, Takehito; Shizuma, Toshiyuki; Miyamoto, Shuji*; Amano, Sho*; Takemoto, Akinori*; Yamaguchi, Masashi*; Horikawa, Ken*; Akimune, Hidetoshi*; Chiba, Satoshi*; Ogata, Kazuyuki*; et al.
Physical Review C, 93(4), p.044313_1 - 044313_4, 2016/04
Times Cited Count:7 Percentile:48.93(Physics, Nuclear)We have measured the azimuthal anisotropy of neutrons emitted from the Fe(, n)Fe reaction with a linearly polarized ray beam generated by laser Compton scattering at NewSUBARU. Neutron yields at the polar angle of 90 have been measured as a function of the azimuthal angle between the detector and the linear polarization plane of the ray beam. The azimuthal anisotropy of neutrons measured at seven angles has been well reproduced using a theoretically predicted function of + cos(2).
Hajima, Ryoichi; Fujiwara, Mamoru
Physical Review Accelerators and Beams (Internet), 19(2), p.020702_1 - 020702_9, 2016/02
Times Cited Count:7 Percentile:48.93(Physics, Nuclear)We propose a scheme to generate narrow-bandwidth GeV photons, -rays, via Compton scattering of hard X-ray photons in an X-ray free-electron laser oscillator. Generated -rays show a narrow-bandwidth spectrum with a sharp peak, 0.1% (FWHM), due to large momentum transfer from electrons to photons. Such -rays will be a unique probe for studying hadron physics. Features of the -ray source, flux, spectrum, polarization, tunability and energy resolution are discussed.
Matsuba, Shunya*; Hayakawa, Takehito; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Angell, C.; Fujiwara, Mamoru; Hajima, Ryoichi
Japanese Journal of Applied Physics, 54(5), p.052203_1 - 052203_5, 2015/05
Times Cited Count:3 Percentile:13.81(Physics, Applied)Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.
JAEA-Research 2014-030, 457 Pages, 2015/03
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.
Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Demongeot, S.*; Gurriaran, R.*; Uwamino, Yoshitomo*; Kato, Hiroaki*; et al.
Journal of Environmental Radioactivity, 139, p.320 - 343, 2015/01
Times Cited Count:91 Percentile:93.1(Environmental Sciences)Saito, Kimiaki; Tanihata, Isao*; Fujiwara, Mamoru; Saito, Takashi*; Shimoura, Susumu*; Otsuka, Takaharu*; Onda, Yuichi*; Hoshi, Masaharu*; Ikeuchi, Yoshihiro*; Takahashi, Fumiaki; et al.
Journal of Environmental Radioactivity, 139, p.308 - 319, 2015/01
Times Cited Count:225 Percentile:98.79(Environmental Sciences)Hayakawa, Takehito; Fujiwara, Mamoru*
Nihon Genshiryoku Gakkai-Shi ATOMO, 56(7), p.448 - 452, 2014/07
It is considered that progress of nuclear security is important in the world. A key technology for nuclear security is non-destructive measurements of hidden nuclear materials and radioactive isotopes in various conditions. For such purpose, we require helps of professional in wide range fields as nuclear physics, accelerator science, laser science, and nuclear fusion science etc. outside of the traditional nuclear engineering.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2013-037, 455 Pages, 2013/12
Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.
Kitamura, Akira; Fujiwara, Kenso; Mihara, Morihiro; Cowper, M.*; Kamei, Gento
Journal of Radioanalytical and Nuclear Chemistry, 298(1), p.485 - 493, 2013/10
Times Cited Count:11 Percentile:63.98(Chemistry, Analytical)Solubility of thorium and americium in pore water squeezed from a cement paste was investigated by a batch method from oversaturation. The ordinary Portland cement was mixed with deionised water to prepare a cement paste from which the pore water was squeezed following solidification. Another batch of pore water was collected by the same method except that a superplasticiser was added to the deionised water used to prepare the cement paste. The aim was to investigate an effect of superplasticiser on solubility of thorium and americium in the squeezed cement porewaters. The obtained solubility values in the two squeezed pore waters (with and without superplasticiser present) were similar. Thermodynamic calculations were performed with the JAEA-TDB thermodynamic database and compared with the experimental data to verify their applicability. This result showed that superplasticisers after mixing with the cement paste did not have a significant effect on solubility of thorium and americium, and the thermodynamic calculations were applicable in the present system. Size distribution of colloidal species of thorium and americium was also investigated.
Shizuma, Toshiyuki; Hajima, Ryoichi; Hayakawa, Takehito; Fujiwara, Mamoru; Sonoda, Takashi; Seya, Michio
Nuclear Instruments and Methods in Physics Research A, 654(1), p.597 - 603, 2011/10
Times Cited Count:4 Percentile:32.67(Instruments & Instrumentation)The general purpose Monte Carlo electron- shower computer code (EGS5) was used to obtain the U, Np, and Pu X-ray response from the hybrid K-edge/XRF densitometry (HKED). In the present simulation, we adopt a monochromatic, linearly polarized photon beam generated by inverse Compton scattering of laser light with high energy electrons from an energy recovery linac. The simulation has been carried out under various conditions of the U, Np, and Pu concentrations to investigate the effect to counting rates as well as counting precision. The results of the simulation show that the assessment time for low concentration Pu input solutions can be reduced by the improvement of signal-to-background ratios. The Np concentration can also be determined with a counting precision of approximately 1% in standard deviation during the 1 hour measurement for a 3N HNO sample solution including U (100 g/L), Np (0.1 g/L), and Pu (20 or 100 g/L).
Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi*; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.
Nuclear Instruments and Methods in Physics Research A, 637(1, Suppl.), p.S141 - S144, 2011/05
Times Cited Count:7 Percentile:48.75(Instruments & Instrumentation)We report the present status of the sub-MeV X-ray generation via Compton backscattering by using 150-MeV electron beam and the Nd:YAG laser. In particular, we show the result of the X-ray generation experiment and of the laser pulse compression for increasing the X-ray flux.
Kono, Takahiko; Ogino, Haruyuki*; Yoshitomi, Hiroshi; Fujiwara, Keiko*; Moriya, Koichi*
FBNews, (410), p.7 - 12, 2011/02
no abstracts in English
Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Nishimori, Nobuyuki; Hayakawa, Takehito; Shizuma, Toshiyuki; Kikuzawa, Nobuhiro; Fujiwara, Mamoru; Seya, Michio
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-31-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2010/12
We have proposed a nondestructive assay for Pu-239 in spent nuclear fuel assembly under water using nuclear resonance fluorescence with energy tunable monochromatic -rays generated by Compton scattering of laser photons and high energy electrons. By using -ray beams of energy of about 2 MeV with good penetrability, one can detect Pu-239 in a spent fuel assembly kept in a water pool from outside the pool wall. In order to realize such -ray source, we are developing technologies for energy-recovery linac (ERL), which is able to generate small-emittance and high-current electron beams. Here we report development status of an electron gun, superconducting cavity and also we present a design of high-flux -ray source based on an ERL.
Hayakawa, Takehito; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Fujiwara, Mamoru; Seya, Michio
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-31-Kai Nenji Taikai Rombunshu (CD-ROM), 5 Pages, 2010/12
We have proposed a nondestructive assay for Pu-239 in spent fuel assembly using nuclear resonance fluorescence with energy tunable monochromatic -rays generated by Compton scattering of laser photons and high energy electrons. This method has advantages that one can detect Pu-239 in a fuel assembly kept in a water pool from outside the pool wall and that one can identify isotopes. We use the -ray beam with the energy of about 2 MeV and thereby we can detect isotopes though water shields with a thickness of several ten centimeters. We present the concept design of this system, the basic study, and detection accuracy of Pu-239 derived from simulation calculation results using a code GEANT4.
Seya, Michio; Hajima, Ryoichi; Nishimori, Nobuyuki; Kikuzawa, Nobuhiro; Hayakawa, Takehito; Shizuma, Toshiyuki; Fujiwara, Mamoru
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-31-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2010/12
Energy-recovery linac based laser Compton scattering (LCS) X/-ray sources have possibilities of various applications to non-destructive assay (NDA) in material accountancy and safeguards verification for future nuclear fuel cycle (FNFC) facilities with advantageous features of very high intensity, monochromaticy and tunability of energy. A LCS-X-ray source with energy of 110-130 keV could be applied to a fast hybrid K-edge densitometer, and a LCS--ray source with energy of 1-3 MeV to a NDA system of Pu (and actinide) in spent nuclear fuel and high-level active waste such as hull or vitrified waste by NRF (nuclear resonance fluorescence) method. The LCS--ray source with energy of 1-3 MeV could be applied to isotopic analysis of Pu etc. for solution, solid and powder samples after nuclear resonance cross section data of actinides is prepared. Also we present an idea of actual deployment of NDA systems using LCS-X/-ray sources in a hypothetical FNFC facility.
Morita, Yoshimune*; Kamiya, Chiho*; Sasaki, Toshinori*; Miyagi, Toyohiko*; Sugai, Toshihiko; Yanagida, Makoto*; Furusawa, Akira*; Fujiwara, Osamu*
Kikan Chirigaku, 62(4), p.195 - 210, 2010/12
It is assumed that the variation of temperature and the precipitation with the climate change may affect geological environment such as the subsurface water flow. Therefore, as well as global climate change from the past to the present, investigation technology to grasp local climate change is indispensable. A palynological study was carried out using the sediment core taken from the Okute Basin, located in the northeast of Mizunami Underground Research Laboratory. As a result, it was appeared that in a interglacial epoch, there was much precipitation around this area, and that in a glacial epoch, became colder and more arid, compared with Kinki region in the same latitude. This shows that the modern analog method with pollen data from the sediment of the inland basin is effective technique to estimate a local climate change.
Hayakawa, Takehito; Kikuzawa, Nobuhiro; Hajima, Ryoichi; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Fujiwara, Mamoru; Seya, Michio
Nuclear Instruments and Methods in Physics Research A, 621(1-3), p.695 - 700, 2010/09
Times Cited Count:42 Percentile:93.02(Instruments & Instrumentation)We propose a new nondestructive assay method for U, Pu, and minor actinides in spent nuclear fuel assembly in a water pool. Nuclear fuel materials are detected using nuclear resonance fluorescence (NRF) with laser Compton scattering (LCS) -rays. The NRF assay can provide a finger print of each isotope since the NRF -ray energy is characteristic of a specific nuclide. We design a high-flux LCS -ray source, in which -rays are generated by collision of laser photons provided from Yb-doped fiber laser and electrons from energy recovery linac. A simulation calculation shows that we can detect 1% fraction Pu in all the fuel rods with statistical error lower than 2% using the high flux LCS -ray source and the measurement time of 4000 s.