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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.
Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi
JAEA-Technology 2022-029, 55 Pages, 2023/02
JAEA-Technology-2022-029.pdf:2.77MB
Japan Materials Testing Reactor (JMTR) was decided as a one of decommission facilities in April 2017. The activation activity of secondary radioactive contamination remaining in the reactor facility was evaluated in order to submit the decommissioning plan to the Nuclear Regulation Authority. Total activation activity was 2.73
10
Bq after 12 years, 1.4610Bq after 21 years, respectively. The system with high activation activity was the primary cooling system in JMTR. The relatively large radionuclide was H-3, Fe-55, Co-60, Ni-63, Sr-90 and Cs-137. The radioactivity level was classified based on the values of the obtained radioactivity concentration. As a result, the primary cooling system and the drain system was classified as L2, and others was classified as L3. The nuclide that affected classification result was only Co-60 in irradiation facility of HR-1 and OSF-1. H-3, Co-60, Sr-90, Cs-137 and so on were affected classification in other system. When treating and disposing of radioactive waste, evaluation will be carried out based on appropriate methods.
Nakano, Hiroko; Nishikata, Kaori; Nagata, Hiroshi; Ide, Hiroshi; Hanakawa, Hiroki; Kusunoki, Tsuyoshi
JAEA-Review 2022-073, 23 Pages, 2023/01
JAEA-Review-2022-073.pdf:2.02MB
A practical training course using the JMTR (Japan Materials Testing Reactor) and other research infrastructures was held from July 24th to July 31st in 2019 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 12 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2019 is reported in this paper.
Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Ide, Hiroshi
JAEA-Technology 2022-017, 113 Pages, 2022/08
JAEA-Technology-2022-017.pdf:6.17MB
Japan Materials Testing Reactor (JMTR) was decided as a one of decommission facilities in April 2017. The activation activity of radioactive materials remaining in the reactor facility was evaluated in order to submit the decommissioning plan to the Nuclear Regulation Authority. Total activation activity was 9.310
Bq after the permanent shutdown of reactor, 2.710
Bq after 21 years, 1.010 Bq after 40 years and 2.410
Bq after 100 years. The structure with high activation activity was the core structural materials in JMTR such as beryllium frame, aluminum reflector, etc., and the material was stainless steel, beryllium, etc. The ratio of nuclides to the total amount of activated radioactivity was highest in H-3 until about 40 years after the reactor shutdown, and then in Ni-63. For reference, the radioactivity level was classified based on the results of the obtained radioactivity concentration. The ratio of the weight of each radioactivity level to the total weight was 0.3-0.4% (10-13t) for L1, 0.0-0.4% (0-14t) for L2, 1.0-1.2% (32-39t) for L3 and 98.0-98.7% (about 3200t) for CL until 100 years after the reactor shutdown. It was found that those classified as CL account for more than 90% of the total. When treating and disposing of radioactive waste, evaluation will be carried out based on appropriate methods, including evaluation results of secondary pollutants.
Seki, Misaki; Fujita, Yoshitaka; Fujihara, Yasuyuki*; Zhang, J.*; Yoshinaga, Hisao*; Sano, Tadafumi*; Hori, Junichi*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; et al.
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 29(1), p.2 - 9, 2022/06
no abstracts in English
Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi; Miyakoshi, Hiroyuki; Takamatsu, Misao; Sakamoto, Naoki; Isozaki, Ryosuke; Onishi, Takashi; et al.
JAEA-Review 2021-020, 42 Pages, 2021/10
JAEA-Review-2021-020.pdf:2.95MB
The disposal of radioactive waste from the research facility need to calculate from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Agency Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2020 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.
Seki, Misaki; Nakano, Hiroko; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Takeuchi, Tomoaki; Ide, Hiroshi; Tsuchiya, Kunihiko
Dekomisshoningu Giho, (62), p.9 - 19, 2020/09
Japan Materials Testing Reactor (JMTR) has been contributing to various research and development activities such as the fundamental research of nuclear materials/fuels, safety research and development of power reactors, and radioisotope production since the beginning of the operation in 1968. JMTR, however, was decided as a one of decommission facilities in April 2017 and it is taken an inspection of a plan concerning decommissioning because the performance of JMTR does not confirm with the stipulated earthquake resistance. As aluminum and beryllium are used for the core structural materials in JMTR, it is necessary to establish treatment methods of these materials for the fabrication of stable wastes. In addition, a treatment method for the accumulated spent ion-exchange resins needs to be examined. This report describes the overview of these examination situations.
Seki, Misaki; Ishikawa, Koji*; Sano, Tadafumi*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi; Tsuchiya, Kunihiko; Fujihara, Yasuyuki*; et al.
KURNS Progress Report 2019, P. 279, 2020/08
no abstracts in English
Eguchi, Shohei; Nakano, Hiroko; Otsuka, Noriaki; Nishikata, Kaori; Nagata, Hiroshi; Ide, Hiroshi; Kusunoki, Tsuyoshi
JAEA-Review 2019-012, 22 Pages, 2019/10
JAEA-Review-2019-012.pdf:3.37MB
A practical training course using the JMTR and other research infrastructures was held from July 31st to August 7th in 2018 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 11 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2018 is reported in this paper.
Seki, Misaki; Ishikawa, Koji*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.
KURNS Progress Report 2018, P. 257, 2019/08
no abstracts in English
Otsuka, Kaoru; Ide, Hiroshi; Nagata, Hiroshi; Omori, Takazumi; Seki, Misaki; Hanakawa, Hiroki; Nemoto, Hiroyoshi; Watanabe, Masao; Iimura, Koichi; Tsuchiya, Kunihiko; et al.
UTNL-R-0499, p.12_1 - 12_8, 2019/03
no abstracts in English
Otsuka, kaoru; Hanakawa, Hiroki; Nagata, Hiroshi; Omori, Takazumi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko
UTNL-R-0496, p.13_1 - 13_11, 2018/03
no abstracts in English
Eguchi, Shohei; Shibata, Hiroshi; Imaizumi, Tomomi; Nagata, Hiroshi; Tanimoto, Masataka; Kusunoki, Tsuyoshi
JAEA-Review 2017-032, 26 Pages, 2018/02
JAEA-Review-2017-032.pdf:2.44MB
A practical training course using the JMTR and other research infrastructures was held from July 24th to August 4th in 2017 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 10 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2017 is reported in this paper.
Hirayama, Hideo*; Kondo, Kenjiro*; Suzuki, Seishiro*; Tanimura, Yoshihiko; Iwanaga, Kohei*; Nagata, Hiroshi*
EPJ Web of Conferences, 153, p.08010_1 - 08010_3, 2017/09
Times Cited Count：2 Percentile：78.04(Nuclear Science & Technology)Pulse height distributions were measured using a CdZnTe detector inside a lead collimator to investigate main source producing high dose rates above the shield plugs of Unit 3 at Fukushima Daiichi Nuclear Power Station. It was confirmed that low energy photons are dominant. Concentrations of Cs-137 under 60 cm concrete of the shield plug were estimated to be between 8.110
and 5.710
Bq/cm
from the measured peak count rate of 0.662 MeV photons. If Cs-137 was distributed on the surfaces of the gaps of the shied plugs with radius 6 m and with the averaged concentration of 5 points, 2.610 Bq/cm, total amount of Cs-137 is estimated to be 30 PBq.
Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.
Journal of Nuclear Materials, 463, p.537 - 540, 2015/08
Times Cited Count：19 Percentile：82.55(Materials Science, Multidisciplinary)Takeuchi, Tomoaki; Otsuka, Noriaki; Shibata, Hiroshi; Nagata, Hiroshi; Endo, Yasuichi; Matsui, Yoshinori; Tsuchiya, Kunihiko
KAERI/GP-418/2015, p.110 - 112, 2015/00
irradiation experiments with a 
Co source were carried out for developing Self-Powered Gamma Detectors (SPGDs) with lead (Pb) emitter and Self-Powered Neutron Detectors (SPNDs) with Pt-40%Rh emitter prior to in-core irradiation experiments. The results showed the output currents of the SPGDs were proportional to the dose rate in the range from about 200-6000 Gy/h with about 10% accuracy. In the case of SPNDs, the output currents flowed in inverse direction and were an order of magnitude lower compared with that of the SPGDs. These different behaviors of the output currents are considered to be caused by the difference in the emitter sizes and the current component originated at the MI cables.
Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.
Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10
Takeuchi, Tomoaki; Shibata, Akira; Nagata, Hiroshi; Kimura, Nobuaki; Otsuka, Noriaki; Saito, Takashi; Nakamura, Jinichi; Matsui, Yoshinori; Tsuchiya, Kunihiko
Proceedings of 3rd Asian Symposium on Material Testing Reactors (ASMTR 2013), p.52 - 58, 2013/11
In-pile instrumentation systems in present LWR's are indispensable to monitor all situations during reactor operation and reactor shut down. However, those systems did not work sufficiently under the conditions like as the severe accident at the Fukushima Dai-Ichi Nuclear Power Station. Therefore, based on the irradiation measurement technique of experiences accumulated in JMTR, the developments of reactor instrumentation systems to prevent severe core damage accident in advance have been started. The development objects are four instrumentation systems, which are a solid electrolysis type hydrogen concentration sensor, a water gauge of thermocouple type equipped with the heater, a -ray detector of self-powered type SPGD, and an image analysis system of Cherenkov light for quantification of in-reactor information by CCD cameras. After the developments, the in-pile verification tests of four instrumentation systems are planned at the JMTR.
Watahiki, Shunsuke; Hanakawa, Hiroki; Imaizumi, Tomomi; Nagata, Hiroshi; Ide, Hiroshi; Komukai, Bunsaku; Kimura, Nobuaki; Miyauchi, Masaru; Ito, Masayasu; Nishikata, Kaori; et al.
JAEA-Technology 2013-021, 43 Pages, 2013/07
JAEA-Technology-2013-021.pdf:5.12MB
The number of research reactors in the world is decreasing because of their aging. On the other hand, the necessity of research reactor, which is used for human resources development, progress of the science and technology, industrial use and safety research is increasing for the countries which are planning to introduce the nuclear power plants. From above background, the Neutron Irradiation and Testing Reactor Center began to discuss a basic concept of Multipurpose Compact Research Reactor (MCRR) for education and training, etc., on 2010 to 2012. This activity is also expected to contribute to design tool improvement and human resource development in the center. In 2011, design study of reactor core, irradiation facilities with high versatility and practicality, and hot laboratory equipment for the production of Mo-99 was carried out. As the result of design study of reactor core, subcriticality and operation time of the reactor in consideration of an irradiation capsule, and about the transient response of the reactor to the reactivity disturbance during automatic control operation, it was possible to do automatic operation of MCRR, was confirmed. As the result of design study of irradiation facilities, it was confirmed that the implementation of an efficient mass production radioisotope Mo-99 can be expected. As the result of design study with hot laboratory facilities, Mo-99 production, RI export devised considered cell and facilities for exporting the specimens quickly was designed.
Nagata, Hiroshi; Inoue, Shuichi; Yamaura, Takayuki; Tsuchiya, Kunihiko; Nagao, Yoshiharu
JAEA-Technology 2013-008, 30 Pages, 2013/06
JAEA-Technology-2013-008.pdf:2.24MB
Refurbishment of JMTR was completed in FY2010. For damage caused by the 2011 off the Pacific coast of Tohoku Earthquake, the repair of facilities was completed in October 2012. Currently, the JMTR is in preparation for restart. Irradiation tests for LWRs safety research, science and technologies, etc. are expected after the JMTR restart. On the other hand, aiming at the attractive irradiation testing reactor, the usability improvement has been discussed. As a part of the usability improvement, shortening of turnaround time was discussed focusing on the fabrication process of irradiation capsules, where the fabrication process was analyzed and reviewed by referring a trial fabrication of the mockup capsule. As a result, it was found that the turnaround time can be shortened 2 months from fabrication period of 6 months with communize of irradiation capsule parts, application of ready-made instrumentation including the sheath heater, reconsideration of inspection process, etc.
