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Yamamoto, Masahiko; Nishida, Naoki; Kobayashi, Daisuke; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kitao, Takahiko; Kuno, Takehiko
JAEA-Technology 2023-004, 30 Pages, 2023/06
JAEA-Technology-2023-004.pdf:1.94MB
Glove-box gloves, that are used for handling nuclear fuel materials at the Tokai Reprocessing Plant (TRP) of the Japan Atomic Energy Agency, have an expiration date by internal rules. All gloves are replaced at a maximum of every 4-year. However, degrees of glove deterioration varies depending on its usage environment such as frequency, chemicals, and radiation dose. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured and technical evaluation method for the glove life-time is established. It was found that gloves without any defects in its appearance have enough physical properties and satisfies the acceptance criteria values of new gloves. Thus, it was considered that the expired gloves could be used for total of 8-year, by adding 4-year of new glove life-time. In addition, the results of extrapolation by plotting the glove's physical properties versus the used years showed that the physical properties at 8-year is on the safer side than the reported physical properties of broken glove. Also, the data are not significantly different from the physical properties of the long-term storage glove (8 and 23 years). Based on these results, life-time of gloves at TRP is set to be 8-year. The frequency of glove inspections are not changed, and if any defects is found, the glove is promptly replaced. Thus, the risk related to glove usage is not increased. The cost of purchasing gloves, labor for glove replacement, and the amount of generated waste can be reduced by approximately 40%, respectively, resulting in more efficient and rationalized glove management.
Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.
JAEA-Technology 2022-039, 117 Pages, 2023/06
JAEA-Technology-2022-039.pdf:11.96MB
Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process
Kobayashi, Daisuke; Yamamoto, Masahiko; Nishida, Naoki; Miyoshi, Ryuta; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kato, Keisuke; Nishino, Saki; Kuno, Takehiko; Kitao, Takahiko; et al.
Nihon Hozen Gakkai Dai-18-Kai Gakujutsu Koenkai Yoshishu, p.237 - 240, 2022/07
All gloves attached to glove-box in Tokai Reprocessing Plant have a fixed expiration date and have to be replaced every 4-year. However, degrees of glove deterioration are different depending on its usage environment (frequency, chemicals, radiation, etc.), because of rubber products. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured, and the life-time of gloves are estimated. As a result, gloves without any defects in its appearance have enough physical property for acceptance criteria of new glove. The extrapolated physical property of glove is sufficiently larger than the reported values of damaged glove. No deterioration in physical properties of gloves, that are periodically replaced without any defects in its appearance, is observed and the usable life-time of the glove is estimated to be 8 years.
Nemoto, Miho*; Ebine, Noriya; Okamoto, Akiko; Hosaka, Yasuhisa*; Tsuzuki, Katsunori; Terada, Hiroaki; Hayakawa, Tsuyoshi; Togawa, Orihiko
JAEA-Technology 2021-013, 41 Pages, 2021/08
JAEA-Technology-2021-013.pdf:2.52MB
When North Korea has carried out nuclear tests, Nuclear Emergency Assistance and Training Center (NEAT) predicts atmospheric dispersion of radionuclides by using the WSPEEDI-II upon requests from Nuclear Regulation Authority (NRA) and submits the predicted results to NRA in cooperation with Nuclear Science and Engineering Center (NSEC). This is a part of the activity of NEAT supporting the Japanese Government in emergency responses. The WSPEEDI-II automatic calculation system specialized for responses to nuclear tests by North Korea was developed by NSEC and was used for responses to three nuclear tests from February 2013 to September 2017. This report describes the transfer and installation of the calculation system to NEAT, and the subsequent maintenance and operation. Future issues for responses to nuclear tests are also described in this report.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
In this study, accident progression analyses in the SFP were performed to investigate cooling effects of the SFP spray and an alternate water injection in the loss-of-pool water accident with MAAP ver. 5.05 beta. Fuel cladding oxidation model which was created by JAEA based on their experimental data was selected and applied in the present calculations. In case of an assessment of SFP spray effects, decay heat, spray fraction going into the fuel assembly, spray droplet diameter, spray start time were selected as analytical parameters. When the SFP spray of 12.5 kg/s (200 GPM) starts 4 hours after the onset of the accident against the spent fuels with 4 months cooling and if the spray fraction going into the fuel assembly is greater than 30%, the maximum cladding temperature can be maintained under 727
C (1000 K), resulting in avoiding the cladding failure.
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 3 Pages, 2018/11
After the accident of Fukushima-unit 1 Nuclear Power Plant, Japanese utilities are newly requested by regulatory body to take prompt measures to enhance the safety of spent fuel pool. The most important objective of this new Japanese standards of regulation is keeping a water level in a Spent Fuel Pool (SFP) under any situations in order to prevent fuel failures due to increase of fuel temperature and to avoid the occurrence of re-criticality accidents. The utilities are considered to install several kinds of safety measures for SFP. For example, a spray injection and an alternate water injection to keep pool water level, and a spent fuel layout, such as 1 by 4, 1 by 8, checkerboard to enhance cooling of the spent fuel in SFP. The objective of the present study is to investigate the effect of spent fuel layout on SFP cooling with MAAP5.04.
Sato, Takeshi; Muto, Shigeo; Akiyama, Kiyomitsu; Aoki, Kazufumi; Okamoto, Akiko; Kawakami, Takeshi; Kume, Nobuhide; Nakanishi, Chika; Koie, Masahiro; Kawamata, Hiroyuki; et al.
JAEA-Review 2014-048, 69 Pages, 2015/02
JAEA-Review-2014-048.pdf:13.91MB
JAEA was assigned as a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national government and/or local governments in case of disaster responses or response in the event of a military attack, etc. In order to fulfill the tasks, the JAEA has established the Emergency Action Plan and the Civil Protection Action Plan. In case of a nuclear emergency, NEAT dispatches specialists of JAEA, supplies the national government and local governments with emergency equipment and materials, and gives technical advice and information. In normal time, NEAT provides various exercises and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response institutions of the national and local governments, police, fire fighters, self-defense forces, etc. in addition to the JAEA itself. The NEAT also researches nuclear disaster preparedness and response, and cooperates with international organizations. In the FY2013, the NEAT accomplished the following tasks: (1) Technical support activities as a designated public institution in cooperation with the national and local governments, etc. (2) Human resource development, exercise and training of nuclear emergency response personnel for the national and local governments, etc. (3) Researches on nuclear disaster preparedness and response, and sending useful information (4) International contributions to Asian countries on nuclear disaster preparedness and response in collaboration with the international organizations
Hanada, Masaya; Kojima, Atsushi; Tanaka, Yutaka; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; et al.
Fusion Engineering and Design, 86(6-8), p.835 - 838, 2011/10
Times Cited Count：13 Percentile：69.64(Nuclear Science & Technology)Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D
beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D beams for 100s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490-500 keV have been successfully produced at a beam current of 1-2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of 
1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.
Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; Kazawa, Minoru; et al.
AIP Conference Proceedings 1390, p.536 - 544, 2011/09
Times Cited Count：7 Percentile：84.66(Physics, Atomic, Molecular & Chemical)no abstracts in English
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08
Times Cited Count：51 Percentile：88.4(Physics, Fluids & Plasmas)Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m
for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 
2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.
Takeishi, Minoru; Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki*; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; et al.
JAEA-Review 2009-048, 177 Pages, 2009/12
JAEA-Review-2009-048.pdf:19.3MBJAEA-Review-2009-048(errata).pdf:0.12MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV; Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2008 to March 2009. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes.
Ogura, Koichi; Fukumi, Atsushi*; Li, Z.*; Orimo, Satoshi; Sagisaka, Akito; Nishiuchi, Mamiko; Kado, Masataka; Mori, Michiaki; Yogo, Akifumi; Hayashi, Yukio; et al.
Journal of the Vacuum Society of Japan, 52(10), p.570 - 574, 2009/10
For accurate control of relativistic laser-plasma interaction under the repetitive operation, we have to measure and control the laser irradiation conditions such as laser parameters, the target shooting accuracy and so on as well as measuring proton parameter on each laser shot. The displacement of the laser shooting position on a tape target, that are used in the high energy proton generation using an ultra-short Ti:sapphire laser system, is measured by observing an X-ray image from laser plasma with an X-ray pinhole camera for each laser shot. The displacement of the shooting position on the target is about 20micron and the accuracy of the target positioning is within 20micron which is small enough for present laser focusing optics with an F number of 3.6 (f=179mm). The technique contributes to accurate control of a repetitive laser driven proton accelerators.
Okano, Masanori; Kuno, Takehiko; Nemoto, Hirokazu*; Yamada, Keiji; Watahiki, Masaru; Hiyama, Toshiaki
Proceedings of INMM 50th Annual Meeting (CD-ROM), 9 Pages, 2009/07
no abstracts in English
Yogo, Akifumi; Daido, Hiroyuki; Mori, Michiaki; Kiriyama, Hiromitsu; Bulanov, S. V.; Bolton, P. R.; Esirkepov, T. Z.; Ogura, Koichi; Sagisaka, Akito; Orimo, Satoshi; et al.
Reza Kenkyu, 37(6), p.449 - 454, 2009/06
The acceleration of protons driven by a high-intensity laser is comprehensively investigated via control of the target density by using ASE just before the time of the main-laser interaction. Two cases were investigated for which the ASE intensity differed by three orders of magnitude: In the low contrast case the beam centre for higher energy protons is shifted closer to the laser-propagation direction of 45, while the center of lower-energy beam remains near the target normal direction. Particle-in-cell simulations reveal that the characteristic proton acceleration is due to the quasistatic magnetic field on the target rear side with the magnetic pressure sustaining a charge separation electrostatic field.
Nakano, Masanao; Isozaki, Hisaaki; Isozaki, Tokuju; Nemoto, Masashi*; Hasunuma, Keiichi*; Kitamura, Takashi*
Umi No Kenkyu, 18(1), p.37 - 55, 2009/01
To investigate the relationship between the wind and the current along the coast, the continuous observation of wind and current carried out for two years. The observed area was off shore Tokai-mura in Ibaraki prefecture, where faces open ocean. Considering the existence of strong pycnocline, the observation was carried out at the shallow depth over the pycnocline. The period of wind and current variation for 1 day and over several days was significant. Although the long period variation is caused from the variation of weather and season, the south current is formed by the permanent north wind component. The high correlation factor (0.64) between wind and surface current at 0.5 m was obtained throughout two years. As the result of harmonic analysis, both wind and current variations of 1 day period were appeared as S1 component tide, and it was confirmed to be land and sea breeze, and wind driven current, respectively. The land and sea breeze, which contains solar component except S1, adds the wind driven current except S1 to the corresponding component tide. From these results, it is considered that the land and sea breeze makes the pseudo S1 tidal current to the sea surface in the open coastal sea.
Takeishi, Minoru; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; Kokubun, Yuji; et al.
JAEA-Review 2008-057, 155 Pages, 2008/11
JAEA-Review-2008-057.pdf:2.15MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of JAEA, Chapter IV; Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged to the atmosphere and the sea during April 2007 to March 2008. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and its trends, meteorological data and discharged radioactive wastes.
Mori, Michiaki; Yogo, Akifumi; Kiriyama, Hiromitsu; Nishiuchi, Mamiko; Ogura, Koichi; Orimo, Satoshi; Ma, J.*; Sagisaka, Akito; Kanazawa, Shuhei; Kondo, Shuji; et al.
IEEE Transactions on Plasma Science, 36(4), p.1872 - 1877, 2008/08
Times Cited Count：7 Percentile：28.47(Physics, Fluids & Plasmas)A dependence of cut-off proton kinetic energy on laser prepulse duration has been observed. ASE pedestal duration is controlled by a fast electro-optic pulse slicer where the risetime is estimated to be 130 ps. We demonstrate a new correlated spectral technique for determining this risetime using a stretched, frequency chirped pulse.
Takeishi, Minoru; Miyagawa, Naoto; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; Kokubun, Yuji; Kato, Chiaki; et al.
JAEA-Review 2007-044, 155 Pages, 2008/02
JAEA-Review-2007-044.pdf:2.58MBJAEA-Review-2007-044(errata).pdf:0.13MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of JAEA, Chapter 4; Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged to the atmosphere and the sea during April 2006 to March 2007. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and its trends, meteorological data and discharged radioactive wastes.
Orimo, Satoshi; Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Ogura, Koichi; Sagisaka, Akito; Li, Z.*; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Japanese Journal of Applied Physics, Part 1, 46(9A), p.5853 - 5858, 2007/09
Times Cited Count：17 Percentile：54.99(Physics, Applied)A laser-driven proton beam with a maximum energy of a few MeV is stably obtained using an ultra-short and high-intensity Titanium Sapphire laser. At the same time, keV X-ray is also generated at almost the same place where protons are emitted. Here, we show the successful demonstration of simultaneous proton and X-ray projection images of a test sample placed close to the source with a resolution of 10
m, which is determined from the source sizes. Although the experimental configuration is very simple, the simultaneity is better than a few hundreds of ps. A CR-39 track detector and imaging plate, which are placed as close as possible to the CR-39, are used as detectors of protons and X-ray. The technique is applicable to the precise observation of microstructures.
