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Hirayama, Hideo*; Kawasaki, Masatsugu; Matsumura, Hiroshi*; Okura, Takehisa; Namito, Yoshihito*; Sanami, Toshiya*; Taki, Mitsumasa; Oishi, Tetsuya; Yoshizawa, Michio
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.295 - 307, 2021/10
Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken
JPS Conference Proceedings (Internet), 33, p.011075_1 - 011075_6, 2021/03
Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.
JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03
In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).
Tsuchikawa, Yusuke; Kai, Tetsuya; Abe, Yuta; Oishi, Yuji*; Sun, Y.*; Oikawa, Kenichi; Nakatani, Takeshi; Sato, Ikken
Nuclear Instruments and Methods in Physics Research A, 991, p.164964_1 - 164964_5, 2021/03
Times Cited Count：0 Percentile：0.02(Instruments & Instrumentation)Peak shape analysis was performed for the energy spectra of Doppler-broadened prompt 
-rays generated by neutron capture reactions with various boride or boron samples. Significant differences were observed between nonmetallic and metallic borides. Minor differences between the peak shapes of prompt -rays from zirconium- and ferro-borons were evaluated by a peak fitting method. The identification of zirconium- and ferro-borons and other types of borides was estimated.
Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08
Cf neutron source with the spherical protection caseKowatari, Munehiko; Nishino, Sho; Romallosa, K. M. D.*; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Oishi, Tetsuya
Radiation Protection Dosimetry, 189(4), p.436 - 443, 2020/05
Times Cited Count：0 Percentile：0.01(Environmental Sciences)The anisotropic emission of neutrons from a cylindrical X1 Cf source with the spherical external casing was experimentally determined. The influence of metal materials and shapes of the external casing to the anisotropy factor, 
(
) was assessed by the Monte Carlo calculation, before performing the measurement. The results of the calculation result implied that light and spherical-shaped external casing decreases the anisotropic emission of neutrons from a cylindrical source and the nature of the material does not affect the anisotropic emission to a large extent. The experimental results obtained when a spherical-shaped aluminum protection case was employed also revealed that the anisotropy factor was close to 1.0 with a wide zenith angle range.
Kowatari, Munehiko; Yoshitomi, Hiroshi; Nishino, Sho; Tanimura, Yoshihiko; Oishi, Tetsuya; Kessler, P.*; Neumaier, S.*; R
ttger, A.*
Radiation Protection Dosimetry, 187(1), p.61 - 68, 2019/12
Times Cited Count：1 Percentile：14.17(Environmental Sciences)Kowatari, Munehiko; Yoshitomi, Hiroshi; Nishino, Sho; Tanimura, Yoshihiko; Oishi, Tetsuya; Kessler, P.*; Neumaier, S.*; Rttger, A.*
Radiation Protection Dosimetry, 186(4), P. 538, 2019/12
Times Cited Count：0 Percentile：1.45(Environmental Sciences)In the original version of this article an error occurred in Table 5. In section (b), the unit 
Sv h
has been amended to nSv h. The corrected table appears below. The author apologises for this error.
Tanimura, Yoshihiko; Nishino, Sho; Yoshitomi, Hiroshi; Kowatari, Munehiko; Oishi, Tetsuya
Progress in Nuclear Science and Technology (Internet), 6, p.134 - 138, 2019/01
At the severe nuclear accidents like the Fukushima Daiichi Nuclear Power Plant, various radionuclides will be dispersed into the environment and raise the dose rate. The 
-
measurements of ray spectra and identifying radionuclides using the results are important for the radiological protection from both external and internal exposure. For this application a commercially available CdZnTe spectrometer (Kromek GR-1) was characterized at the calibration fields of FRS/JAEA. The angular dependence of the detection efficiency was studied and the efficiency was kept within 15 % degradation in 
135 degree incident angle, which covers 85 % of all. The usable dose range was evaluated and the spectrometer could correctly measure the ray spectra below 200 Gy/h.
Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
pre-concentration of Sr from large volume of freshwater sample using Powdex resinTomita, Jumpei; Yamamoto, Masayoshi*; Nozaki, Teo; Tanimura, Yoshihiko*; Oishi, Tetsuya
Journal of Environmental Radioactivity, 146, p.88 - 93, 2015/08
Times Cited Count：11 Percentile：36.14(Environmental Sciences)Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sonoda, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro*; Tsukada, Kazuaki; et al.
Journal of the Physical Society of Japan, 82(6), p.064201_1 - 064201_7, 2013/06
Times Cited Count：40 Percentile：85.44(Physics, Multidisciplinary)Okura, Takehisa; Oishi, Tetsuya; Taki, Mitsumasa; Shibanuma, Yukio; Kikuchi, Masamitsu; Akino, Hitoshi; Kikuta, Yasuaki; Kawasaki, Masatsugu; Saegusa, Jun; Tsutsumi, Masahiro; et al.
JAEA-Data/Code 2012-010, 37 Pages, 2012/05
JAEA-Data-Code-2012-010.pdf:2.28MB
Due to the accident at Fukushima Daiichi Nuclear Power Plant caused by the 2011 off the Pacific coast of Tohoku Earthquake occurred at 11th March 2011, the emergency environmental radiation monitoring was conducted at Nuclear Science Research Institute, Japan Atomic Energy Agency (JAEA). This report provides the monitoring results of ambient -ray dose rate and atmospheric radioactivity concentration until the beginning of June 2011. Some anthropogenic radionuclides such as Cs-134, Cs-137, I-131, I-132, Te-132, Xe-133 and others were detected from air samples. The atmospheric radioactivity concentrations varied with some peaks corresponded with that of ambient -ray dose rate after 15th March 2011. Composition of each peak showed various characteristic. Internal exposure caused by inhalation was estimated from the observed atmospheric radioactivity.
Okura, Takehisa; Oishi, Tetsuya; Moriyama, Hirobumi; Miyagawa, Naoto
JAEA-Testing 2009-009, 46 Pages, 2010/03
JAEA-Testing-2009-009.pdf:7.13MB
The meteorological observation at Tokai site has conducted based on a "Guideline of meteorological statistics for the safety analysis of nuclear power reactor" (Nuclear Safety Commission on January 28, 1982; revised on March 29, 2001) at Nuclear Science Research Institute in JAEA. The meteorological field was changed in 2005. This report shows assessments of the effect on the change of the meteorological field on April 2005.
Sagisaka, Akito; Daido, Hiroyuki; Pirozhkov, A. S.; Ma, J.-L.; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Nishiuchi, Mamiko; Kawachi, Tetsuya; et al.
IEEE Transactions on Plasma Science, 36(4), p.1812 - 1816, 2008/08
Times Cited Count：4 Percentile：17.79(Physics, Fluids & Plasmas)We observe UV harmonics and protons with a thin-foil target irradiated with a high-intensity Ti:sapphire laser. The laser intensity dependency of UV harmonics and proton signal is measured by varying the distance between the target surface and the best focus of the laser beam. In the case of appropriate condition for proton generation with a maximum energy of 
2.7 MeV, the weak broad spectrum in the UV region is generated. The UV harmonics up to fourth-order are generated as the target is moved away from the best focus position. In this condition the maximum energy of protons is reduced to 1 MeV.
Oishi, Takuma*; Sasaki, Atsushi*; Hamada, Nobuyuki*; Ishiuchi, Shogo*; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Nakano, Takashi*; Nakazato, Yoichi*
Neuropathology, 28(4), p.408 - 416, 2008/08
Times Cited Count：12 Percentile：43.39(Clinical Neurology)-ray detectionYamasoto, Kotaro; Tsutsumi, Masahiro; Oishi, Tetsuya*; Yoshizawa, Michio; Yoshida, Makoto
Nuclear Instruments and Methods in Physics Research A, 550(3), p.609 - 615, 2005/09
Times Cited Count：4 Percentile：30.73(Instruments & Instrumentation)A phoswich detector composed of a thin plate CsI(Tl) scintillator and a plastic scintillator (BC-400) has been designed and evaluated to improve the sensitivity in the low-energy region of large-area plastic scintillation detector. Applicability of the CsI(Tl)/Plastic phoswich detector was examined on radioactivity measurement of massive and large-area materials. The rise-time discrimination technique was applied in order to further improve the minimum detectable activity in the low-energy region. On the basis of the estimation of minimum detectable activity, it was made clear that the energy range of large-area plastic scintillation detector can be expanded down to a few tens of keV by adding a thin plate CsI(Tl) scintillator.
Tsutsumi, Masahiro; Oishi, Tetsuya*; Yamasoto, Kotaro; Yoshida, Makoto
JAERI-Research 2004-021, 43 Pages, 2004/12
JAERI-Research-2004-021.pdf:8.55MB
We have designed and developed a measurement system to certify radioactive wastes below the clearance level. By advancing non-destructive -ray assay technology, it aims at quantitative determination of radionuclides contained in 200 litter drum/container wastes. Unlike the waste from a nuclear power plant, you have to assume that the waste originating from radioisotope usage and nuclear research laboratory have a variety of contents and a complex mixture of radionuclides, and furthermore the uniformity of activity concentration is unknown. To cope with the problems, we have developed the -ray measuring instruments (units) with effective improvement of capability against each problem. They are (1) germanium spectrometry unit for enhanced peak identification, (2) positioning detection unit for positioning of interactions and (3)high-efficiency detection unit for separation of low-energy component. This report summarizes the direction of the clearance level measuring system and the three developed measuring units with their performances.
ray detection systemsOishi, Tetsuya
RIST News, (36), p.12 - 20, 2003/10
no abstracts in English
-ray detection systemsOishi, Tetsuya; Tsutsumi, Masahiro; Sugita, Takeshi*; Yoshida, Makoto
Journal of Nuclear Science and Technology, 40(6), p.441 - 445, 2003/06
Times Cited Count：1 Percentile：11.08(Nuclear Science & Technology)An EGS4 user code has been developed to design and optimize ray detection systems for several types of radiation sources. The code is fundamentally based on the PRESTA-CG, which is improved on the electron transport in the EGS4 and specialized for the utilization of a combinatorial geometry (CG) method. The main additional functions in the present user code are classified into two parts of the definition of radiation sources and the transport of photons. The developed user code was applied to two types of detection systems in order to demonstrate its availability. As the result, it was found that the present code allows the detailed response analysis of complicated detection systems for several sources with just a simple handling.
