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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
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.
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.
Nishinaka, 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:61(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.
Maeda, 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:8 Percentile:61(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.
Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Ri, Keiko*; Yamada, Norihiro*; Ishiguro, Rika*; Maeda, Eita*; Makii, Hiroyuki; Hashimoto, Kazuyuki; et al.
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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.
Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Watanabe, Shigeki; Ishioka, Noriko; Hashimoto, Kazuyuki
no journal, ,
Nishinaka, Ichiro; Makii, Hiroyuki; Toyoshima, Atsushi; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Taniguchi, Takumi*; Watanabe, Shigeki; et al.
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no abstracts in English
Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yamada, Norihiro*; Makii, Hiroyuki; Toyoshima, Atsushi; Watanabe, Shigeki; Ishioka, Noriko; et al.
no journal, ,
Production cross sections of astatine in 29-57 MeV Li + Pb 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 the Li + Pb reaction. It indicates that the breakup of Li plays a rule in the Li + Pb reaction. Besides, we have developed a dry-distillation method which separates carrier-free astatine from an irradiated lead target.
Nishinaka, 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.
Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Taniguchi, Takumi*; Murakami, Kento*; Watanabe, Shigeki; Suzuki, Hiroyuki; Ishioka, Noriko; et al.
no journal, ,
In general, an -emitter At which is a prospective candidate for utilization in targeted alpha radiotherapy is produced through the Bi(He, 2n)At reaction. In contrast, our project is focusing on the production in the Bi(Li, 5n)Rn reaction. This enables us to supply At in a Rn/At generator system. The daughter At (7.2 h half-life) is extracted from the parent Rn (14h), expanding time-frame for transportation and use of At. To use astatine and iodine radioisotopes in our project, the excitation functions of Bi(Li, xn)Rn, Pb(Li, xn)At and Sn(Li, xn)I reactions have been measured. In addition to that, separation techniques have been developed. We report not only on the production and separation of astatine and iodine radioisotopes in the reactions but also on the utilization of those radioisotopes.
Iwasa, Atsutoshi; Nakayama, Naoto; Maeda, Eita; Usui, Toshihide; Kano, Yutaka; Takashima, Hideki; Irokawa, Hiroyuki
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no abstracts in English
Washiyama, Koshin*; Maeda, Eita*; Yokoyama, Akihiko*; Nishinaka, Ichiro; Taniguchi, Takumi*; Yamada, Norihiro*; Makii, Hiroyuki; Toyoshima, Atsushi; Amano, Ryohei*
no journal, ,
A Rn/At generator for targeted alpha therapy has been developed.
Nishinaka, 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.
Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yokoyama, Akihiko*; Nishinaka, Ichiro; Takahashi, Naruto*; Shinohara, Atsushi*; Watanabe, Shigeki; Ishioka, Noriko
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In order to use of an alpha emitter for targeted alpha therapy, we have started the production and the utilization of At using 30 MeV He particle in the Bi(He, 2n)At nuclear reaction at cyclotron facilities of Osaka University and JAEA Takasaki. In addition to that, we have been developing a Rn/At generator to expand the availability of At to wide range of populations far away from cyclotron facilities. The results of studies on the At-chemistry for clinical use and on the development of the Rn/At generator will be presented. And a review of current status of targeted alpha therapy in Japan will be also introduced.
Kato, Yoshinari; Hashimoto, Makoto; Miyauchi, Hideaki; Yasumune, Takashi; Maeda, Eita; Takasaki, Koji; Yoshizawa, Michio; Momose, Takumaro
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Ayame, Junko; Maeda, Eita; Koike, Yuko; Mitsumoto, Rika; Nakano, Minako; Uehara, Shieru
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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
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Inoue, Yuki; Yamada, Junya; Maeda, Eita; Hatakeyama, Takumi; Miyauchi, Hideaki; Hashimoto, Makoto
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no abstracts in English
Takada, Chie; Nakano, Masanao; Munakata, Masahiro; Yoshida, Tadayoshi; Yokosuka, Yoshiyuki; Yamada, Junya; Maeda, Eita; Watanabe, Yuki; Tomioka, Akifumi; Momose, Takumaro
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Takada, Chie; Nakano, Masanao; Munakata, Masahiro; Yoshida, Tadayoshi; Yokosuka, Yoshiyuki; Yamada, Junya; Maeda, Eita; Watanabe, Yuki; Tomioka, Akifumi; Momose, Takumaro
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no abstracts in English