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Nagata, Hiroshi; Omori, Takazumi; Maeda, Eita; Otsuka, Kaoru; Nakano, Hiroko; Hanakawa, Hiroki; Ide, Hiroshi
JAEA-Review 2023-033, 40 Pages, 2024/01
JAEA-Review-2023-033.pdf:1.39MB
Japan Materials Testing Reactor (JMTR) was decided as a one of decommission facilities in April 2017. In order to submit the decommissioning plan to the Nuclear Regulation Authority, the type of accident assumed in the first stage of the decommissioning plan was selected, and the public exposure dose was evaluated. A fuel handling accident and a fire accident during storage of waste were selected as assumed accidents in the first stage of the decommissioning plan. An evaluation of the public exposure dose from the radioactive materials released into the atmosphere due to these accidents was estimated to be a maximum of 0.019 mSv (due to a fire accident during storage of waste). This estimated value was found to be sufficiently smaller than the judging criteria (5 mSv), and not to pose a significant risk of radiation exposure to the general public.
Kato, Masato; Machida, Masahiko; Hirooka, Shun; Nakamichi, Shinya; Ikusawa, Yoshihisa; Nakamura, Hiroki; Kobayashi, Keita; Ozawa, Takayuki; Maeda, Koji; Sasaki, Shinji; et al.
Materials Science and Fuel Technologies of Uranium and Plutonium mixed Oxide, 171 Pages, 2022/10
Innovative and advanced nuclear reactors using plutonium fuel has been developed in each country. In order to develop a new nuclear fuel, irradiation tests are indispensable, and it is necessary to demonstrate the performance and safety of nuclear fuels. If we can develop a technology that accurately simulates irradiation behavior as a technology that complements the irradiation test, the cost, time, and labor involved in nuclear fuel research and development will be greatly reduced. And safety and reliability can be significantly improved through simulation of nuclear fuel irradiation behavior. In order to evaluate the performance of nuclear fuel, it is necessary to know the physical and chemical properties of the fuel at high temperatures. And it is indispensable to develop a behavior model that describes various phenomena that occur during irradiation. In previous research and development, empirical methods with fitting parameters have been used in many parts of model development. However, empirical techniques can give very different results in areas where there is no data. Therefore, the purpose of this study is to construct a scientific descriptive model that can extrapolate the basic characteristics of fuel to the composition and temperature, and to develop an irradiation behavior analysis code to which the model is applied.
Nakano, Masanao; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Okura, Takehisa; Kuramochi, Akihiko; Kawasaki, Masatsugu; Takeuchi, Erina; Fujii, Yutaka*; Jinno, Tsukasa*; et al.
Hoken Butsuri (Internet), 55(2), p.102 - 109, 2020/06
After the Fukushima-Daiichi Nuclear Power Station (1F) Accident in March 2011, the increase was significantly observed in a part of the result of the environmental radiation monitoring in Ibaraki prefecture. "The review meeting of the environmental effect from 1F accident" was established to discuss technically the fluctuation of monitoring data. The review meeting collected the monitoring data from the four nuclear operators, and discussed a fluctuating trend, 
Cs/
Cs activity ratio, and so on. In this report, the results of the dose rate and Cs in fallout, surface soil, flatfish and seabed sediment are introduced. Also the problem solving in the review meeting is introduced.
Xe ions on proton, deuteron, and carbon targetsSun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.
Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06
Times Cited Count：5 Percentile：51.18(Physics, Nuclear)The spallation and fragmentation reactions of Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：8 Percentile：55.27(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Li + 
Pb reactionNishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Maeda, Eita*; Watanabe, Shigeki; Hashimoto, Kazuyuki; Ishioka, Noriko; Makii, Hiroyuki; Toyoshima, Atsushi; Yamada, Norihiro*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 304(3), p.1077 - 1083, 2015/06
Times Cited Count：9 Percentile：60.04(Chemistry, Analytical)Production cross sections of astatine isotopes 
At in the 29-57 MeV Li induced reaction with Pb target have been measured by 
- and 
-ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of Li + Pb. Considerably small experimental cross sections of 
At and 
At compared with the calculation were clearly observed at incident energies higher than 44 MeV, indicating that the effects of breakup reaction play a role. A chemical separation of astatine from an irradiated lead target has been studied with a dry-distillation method. A complementary way to produce astatine isotopes has been developed.
Rn-At generatorMaeda, Eita*; Yokoyama, Akihiko*; Taniguchi, Takumi*; Washiyama, Koshin*; Nishinaka, Ichiro
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1465 - 1468, 2015/02
Times Cited Count：9 Percentile：60.04(Chemistry, Analytical)The At isotope has gathered attention as a promising -emitter for radionuclide therapy. We report the dependence of the distribution ratio of astatine on the concentration of HCl, and on the polarity of the organic solvent. The results will be useful for development of the Rn-At generator.
At for alpha radiotherapy via Bi(Li,5n)RnNishinaka, Ichiro; Washiyama, Koshin*; Yokoyama, Akihiko*; Maeda, Eita*; Hashimoto, Kazuyuki; Makii, Hiroyuki
no journal, ,
A Rn/At generator has been proposed to supply a radiotracer At with a half-life (T
= 7.2 h) for medical applications. To establish a technology of the Rn/At generator, Rn (T = 14.7 h) has to be produced through the Bi(Li, 5n)Rn reaction without melting bismuth metal targets due to heat produced by the irradiation of 60 MeV Li ion beams. In this work, we have studied the effects of a He gas cooling system of an irradiation chamber constructed for the production of Rn. Irradiations were carried out at the JAEA tandem accelerator using the irradiation chamber equipped with the He gas cooling system. The results show that the He gas effectively cools the targets and the cooling efficiency is nearly independent of the pressure (
1 kPa) and the flow rate (
20 L/min) of the He gas.
Ayame, Junko; Maeda, Eita; Koike, Yuko; Mitsumoto, Rika; Nakano, Minako; Uehara, Shieru
no journal, ,
Atomic Energy Society of Japan for 2018 Oral Presentation the winning a prize contents of "excellent active prize" in 2016 Fall Meeting. We were awarded the Outstanding Active Award of Social and Environmental Division, Atomic Energy Society of Japan in the 2018 Annual Meeting. We will present the award lecture at the Planning Session of Social and Environmental Division in the 2018 Fall Meeting.
Yasumune, Takashi; Kato, Yoshinari; Maeda, Eita; Miyauchi, Hideaki; Hashimoto, Makoto; Takasaki, Koji
no journal, ,
no abstracts in English
Takada, Chie; Nakano, Masanao; Munakata, Masahiro; Yoshida, Tadayoshi; Yokosuka, Yoshiyuki; Yamada, Junya; Maeda, Eita; Watanabe, Yuki; Tomioka, Akifumi; Momose, Takumaro
no journal, ,
no abstracts in English
Hitomi, Keitaro*; Maeda, Shigetaka; Nogami, Mitsuhiro*; Ito, Chikara; Watanabe, Kenichi*
no journal, ,
A 2-cm thick pixelated TlBr detector was fabricated in this study. A 50-mm diameter TlBr crystal was grown by the Bridgman-Stockbarger method using zone-purified materials. A pixelated TlBr detector was fabricated from the grown crystal with the dimension of 20 mm 
20 mm 20 mm. The planar cathode and pixelated anodes were constructed on the crystal by vacuum evaporation of Tl. The anode consisted of 16-pixel electrodes (3 mm 3 mm) surrounded by a guard ring. A charge-sensitive preamplifier was connected to a pixel electrode on the device. The output signals from the preamplifier were recorded with a digitizer. The acquired signal waveforms were analyzed with a PC event by event for obtaining pulse-height spectra. The cathode surface of the pixelated TlBr detector was irradiated with an Am-241 gamma-ray source at room temperature. The applied bias voltage to the cathode was 2000 V. A clear full-energy peak corresponding to 59.5-keV gamma rays was obtained from the detector. The clear full-energy peak of 59.5-keV gamma-ray was reflecting the good electron transport property of the TlBr crystal.
Watanabe, Kenichi*; Nogami, Mitsuhiro*; Hitomi, Keitaro*; Maeda, Shigetaka
no journal, ,
Thallium bromide (TlBr) is a semiconductor attractive for gamma-ray detectors. TlBr detectors have been shown excellent energy resolution, however, these results were obtained from small crystal detectors. The next step of TlBr development is to increase the detector size and improve the yield rate of detector production. Therefore, we would like to establish a crystal quality evaluation procedure to improve the yield rate of detector production. As the crystal quality evaluation methods, we apply the neutron Bragg-dip imaging, which is based on the neutron diffraction technique, and the electron backscattering diffraction. The results obtained by the both techniques are compared. The both techniques shows almost the same information. We concluded that the TlBr crystal quality can be efficiently evaluated by complementarily combining the both techniques.
Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Onabe, Hideaki*
no journal, ,
Thallium bromide (TlBr) is a compound semiconductor attractive for gamma-ray spectrometers. TlBr detectors have shown excellent energy resolution, however, these results were obtained from relatively small crystal detectors. The next phase of TlBr development is to increase the detector size and improve the yield rate of detector production. So far, we have evaluated crystal quality of TlBr by using the neutron Bragg-dip imaging, which is one of the neutron diffraction techniques. In this study, we prepared a large TlBr crystal wafer with a diameter and thickness of 50 mm and 12 mm, respectively. We evaluated the quality of the large crystal by the neutron Bragg-dip imaging. The center region of the large TlBr crystal confirmed to be uniform and well-aligned. As a future work, we will evaluate the electric properties, such as the mobility-lifetime product, at various positions in this large crystal.
Igarashi, Yu; Hamaguchi, Takumi; Maeda, Eita; Yamada, Junya; Muto, Yasunobu; Tanigaki, Minoru*; Nohara, Naofumi
no journal, ,
At the JAEA Oarai Research Establishment, a portable KURAMA equipped with a data transmission function through an autonomous network using the ZETA standard was permanently installed near the MP for the purpose of redundancy in the measurement of monitoring points, and a system for observing radiation doses near the site boundary was developed. In this presentation, we report on the fixed point observation data for about one year using this system.
Li+Pb reaction and simple chemical separation of astatineNishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Ri, Keiko*; Yamada, Norihiro*; Ishiguro, Rika*; Maeda, Eita*; Makii, Hiroyuki; Hashimoto, Kazuyuki; et al.
no journal, ,
We have started to study production and utilization of an radioactive nuclide At which is a prospective candidate for targeted alpha radiotherapy. We determined production cross sections of astatine radioisotopes in the reaction of 29-48 MeV Li+Pb by -ray and -ray spectrometry at the tandem accelerator of JAEA-Tokai. Besides, we developed a simple dry-chemical method for separation of astatine.
Igarashi, Yu; Hamaguchi, Takumi; Maeda, Eita; Yamada, Junya; Muto, Yasunobu; Nohara, Naofumi
no journal, ,
At the Oarai Research Institute of the Japan Atomic Energy Agency, a portable KURAMA equipped with a data transmission function using an autonomous network based on the ZETA standard was permanently installed in the vicinity of the MP, and a system for observing radiation doses around the site boundary was developed. In this presentation, the background to the redundancy of post-measurement monitoring, which is the purpose of this system installation, and the fixed-point observation data for about one year will be reported.
Pb reactionNishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Watanabe, Shigeki; Ishioka, Noriko; Hashimoto, Kazuyuki
no journal, ,
Pb reaction; Aim at the new cancer medical treatment by -emitting radioisotopesNishinaka, Ichiro; Makii, Hiroyuki; Toyoshima, Atsushi; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Taniguchi, Takumi*; Watanabe, Shigeki; et al.
no journal, ,
no abstracts in English
Li+Pb reactionNishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Toyoshima, Atsushi; Watanabe, Shigeki; Ishioka, Noriko; et al.
no journal, ,
To promote utilization of a radioactive nuclide At which draws increasing attention as a promissing -emitter for targeted alpha therapy, we have measured production cross sections of astatine isotopes in the 29-57 MeVLi+Pb reaction using the tandem accelerator of JAEA-Tokai, providing nuclear data for production. For pharmaceutical study and so on, beside, we have developed a new separation procedure based on a dry-distillation method which separates carrier free astatine isotopes from lead targets with high radiochemical and chemical purity and high yields.
