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Sekine, Megumi; Sukegawa, Hidetoshi; Ishikuro, Yasuhiro; Oyama, Koji; Obata, Takashi; Hayashi, Kazuhiko; Inoue, Naoko
Proceedings of INMM & ESARDA Joint Virtual Annual Meeting (Internet), 10 Pages, 2021/08
The Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency (JAEA) developed the virtual tour of a reference nuclear facility. The developed virtual tour was applied to the Design Information Questionnaire (DIQ) workshop exercise for the online SSAC course held in November 2020 in connection with the IAEA safeguards-related regional training course. Also, it was applied to the Complementary Access (CA) exercise for the online workshop of the Nuclear Security and Safeguards Project under the Forum for Nuclear Cooperation in Asia (FNCA), held in February 2021. The workshop exercises have been implemented for in-person format however due to COVID-19 pandemic, a virtual tour was applied. The virtual tour was found to be a strong tool not only for online training as an alternative for a facility tour, but also considered to be more advantageous even for the in-person training. The developed virtual tour of a reference nuclear facility, going to shut down, can find potentially varied applications. The paper describes how to create a virtual tour of a reference research reactor facility for the DIQ and CA exercises respectively which have different learning objectives. It emphasizes how the features of the reference facility were captured and the challenges encountered to convey to the training participants the importance of providing the required design information while not being physically present at the facility. It also show the advantage of using the same virtual tour to describe the safeguards-related verification activities of a complementary access. Virtual tours can be applied to a variety of training.
Hashimoto, Makoto; Kinase, Sakae; Munakata, Masahiro; Murayama, Takashi; Takahashi, Masa; Takada, Chie; Okamoto, Akiko; Hayakawa, Tsuyoshi; Sukegawa, Masato; Kume, Nobuhide*; et al.
JAEA-Review 2020-071, 53 Pages, 2021/03
JAEA-Review-2020-071.pdf:2.72MB
In the case of a nuclear accident or a radiological emergency, the Japan Atomic Energy Agency (JAEA), as a designated public corporation assigned in the Disaster Countermeasures Basic Act and the Armed Attack Situation Response Law, undertakes technical supports to the national government and local governments. The JAEA is requested to support to evaluate radiation doses to residents in a nuclear emergency, which is specified in the Basic Disaster Management Plan and the Nuclear Emergency Response Manual. For the dose evaluation, however, its strategy, target, method, structure and so on have not been determined either specifically or in detail. This report describes the results of investigation and consideration discussed in the "Working Group for Radiation Dose Evaluation at a Nuclear Emergency" established within the Nuclear Emergency Assistance and Training Center to discuss technical supports for radiation dose evaluation to residents in the case of a nuclear emergency, and aims at contributing to specific and detailed discussion and activities in the future for the national government and local governments, also within the JAEA.
Sono, Hiroki; Sukegawa, Kazuhiro; Nomura, Norio; Okuda, Eiichi; Study Team on Safety and Maintenance; Study Team on Quality Management; Task Force on New Nuclear Regulatory Inspection Systems
JAEA-Technology 2020-013, 460 Pages, 2020/11
JAEA-Technology-2020-013.pdf:13.46MB
Japan Atomic Energy Agency (JAEA) has completed the introduction of a new frame work of safety, maintenance and quality management activities under the new acts on the Regulation of nuclear source material, nuclear fuel material and reactors since April 2020, in consideration of variety, specialty and similarity of nuclear facilities of JAEA (Power reactor in the research and development stage, Reprocessing facility, Fabrication facility, Waste treatment facility, Waste burial facility, Research reactor and Nuclear fuel material usage facility). The JAEA task forces on new nuclear regulatory inspection systems prepared new guidelines on (1) Safety and maintenance, (2) Independent inspection, (3) Welding inspection, (4) Free-access response, (5) Performance indicators and (6) Corrective action program for the JAEA's nuclear facilities. New Quality management systems and new Safety regulations were also prepared as a typical pattern of these facilities. JAEA will steadily improve these guidelines, quality management systems and safety regulations, reviewing the official activities under the new regulatory inspection system together with the Nuclear Regulation Authority and other nuclear operators.
Nakagawa, Yosuke; Sukegawa, Hidetoshi; Naoi, Yosuke; Inoue, Naoko; Noro, Naoko; Okuda, Masahiro
Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11
The physical protection exercise field, a facility equipped with various types of equipment such as sensors, cameras and fences that are used at nuclear facilities, is an effective tool for training on nuclear security at ISCN/JAEA, if it is carried out in-person. Due to the COVID-19 pandemic, the virtual tour of the facility is developed for the online training courses so that they could be more effective. The article explains the initial development of the virtual tour with some improvement inspired by using it on some occasions as well as a prospect of effective use of the virtual tour based on its characteristics.
Sukegawa, Atsuhiko; Okuno, Koichi*
IEEE Transactions on Plasma Science, 43(11), p.3916 - 3920, 2015/11
Times Cited Count：1 Percentile：4.7(Physics, Fluids & Plasmas)In the present study a comparison between simulations using the PHITS code and activated material analysis of JT-60U has been performed. Neutron transport have been simulated using the Monte Carlo methods PHITS to determine the neutron fluency at the irradiation position. The Activated analysis has been complemented by the foil-activation technique. The preliminary result of these PHITS simulations has been confirmed by comparing the reaction rates of gold, cobalt, and nickel foils activation. The simulation results by PHITS consisted with the measured reaction rate of each foils near the device.
Sukegawa, Atsuhiko; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka
Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10
Times Cited Count：2 Percentile：17.57(Nuclear Science & Technology)The JT-60SA project is a EU - JA satellite tokamak under Broader Approach in support of the ITER project. In-vessel coils are designed and assembled by JA. The resin-insulator is required to have a heat resistance against the baking temperature of vacuum vessel of 
200
C (40000 hour). Thus the assessment of the heat load is fundamental for the design of the coils. However, the estimation of the lifetime of resin-insulator under the high-temperature region has not been examined. In the present study, the estimation of the lifetime of seven candidate resin-insulators such as epoxy resin and cyanate-ester resin under the 220C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180C, 200C and 220C environment using three thermostatic ovens, respectively. The reduction of the insulators has been used as input for Weibull-analysis towards Arrhenius-plot. Lifetime of the resins has been estimated for the first time at the high temperature region by the plot. Lifetime of the resin-insulators have been evaluated and discussed as well as the available temperature of the in-vessel coils.
Maebara, Sunao; Sukegawa, Keiichi*; Tadano, Shuya*; Kasugai, Atsushi; Suzuki, Hiromitsu; Abe, Kazuhiko*; Oku, Ryuji*; Sugimoto, Masayoshi
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1140 - 1142, 2015/09
For the IFMIF/EVEDA accelerator prototype RFQ linac, the operation frequency of 175MHz was selected to accelerate a large current of 125mA. The driving RF power of 1.28MW by 8 RF input couplers has to be injected to the RFQ cavity for CW operation mode. For each RF input coupler, nominal RF power of 160kW and maximum transmitted RF power of 200kW are required. For this purpose, an RF input coupler with cooling functions was designed, based on a 6 1/8 inch co-axial waveguide, and the RF coupler was manufactured by way of trial. For the trial RF coupler, high-power tests using a high voltage standing wave on a high-Q load circuit wave were carried out, and a 200kW-14 sec CW operation were performed after four days of RF aging. No RF contact defects, unnecessary low-Q value and extraordinary outgassing were observed. This report describes the high-power tests of the RF input coupler.
Sukegawa, Atsuhiko; Iida, Hiromasa*; Itoga, Toshio*; Okumura, Keisuke; Kai, Tetsuya; Konno, Chikara; Nakashima, Hiroshi; Nakamura, Takashi*; Ban, Shuichi*; Yashima, Hiroshi*; et al.
Hoshasen Shahei Handobukku; Kisohen, p.299 - 356, 2015/03
no abstracts in English
Shimada, Taro; Sukegawa, Takenori
Journal of Nuclear Science and Technology, 52(3), p.396 - 415, 2015/03
Times Cited Count：1 Percentile：9.74(Nuclear Science & Technology)Radiation source models in DecDose code for assessing public and worker exposure doses during the decommissioning of nuclear facilities were improved in this study. A segmentation model evaluating the length, volume, and surface area of kerfs in the object to be dismantled was improved to deal with seven shapes of objects simulating most of the components and the structures in nuclear facilities. Models for the evaluation of the external dose by direct and skyshine radiation were also improved to deal with the distribution of waste containers temporarily placed in the building and the quantity of radionuclides stored in the individual container. Good agreement was observed between actual and calculated kerf volumes in cutting some components such as the reactor pressure vessel of the Japan Power Demonstration Reactor. It is an indication of the validity of the model improved in this study. On the other hand, some discrepancies were observed between actual and calculated quantities of radionuclides discharged into the ocean, indicating the necessity of further validation of the model.
Ikeda, Yoshitaka; Okano, Fuminori; Sakasai, Akira; Hanada, Masaya; Akino, Noboru; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; Kubo, Hirotaka; Kobayashi, Kazuhiro; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(4), p.167 - 178, 2014/12
The JT-60U torus was disassembled so as to newly install the superconducting tokamak JT-60SA torus. The JT-60U used the deuterium for 18 years, so the disassembly project of the JT-60U was the first disassembly experience of a fusion device with radioactivation in Japan. All disassembly components were stored with recording the data such as dose rate, weight and kind of material, so as to apply the clearance level regulation in future. The lessons learned from the disassembly project indicated that the cutting technologies and storage management of disassembly components were the key factors to conduct the disassembly project in an efficient way. After completing the disassembly project, efforts have been made to analyze the data for characterizing disassembly activities, so as to contribute the estimation of manpower needs and the radioactivation of the disassembly components on other fusion devices.
Shinohara, Koji; Ishii, Keiichi*; Ochiai, Kentaro; Baba, Mamoru*; Sukegawa, Atsuhiko; Sasao, Mamiko*; Kitajima, Sumio*
Review of Scientific Instruments, 85(11), p.11E823_1 - 11E823_4, 2014/11
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)Ikeda, Yoshitaka; Okano, Fuminori; Hanada, Masaya; Sakasai, Akira; Kubo, Hirotaka; Akino, Noboru; Chiba, Shinichi; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; et al.
Fusion Engineering and Design, 89(9-10), p.2018 - 2023, 2014/10
Times Cited Count：2 Percentile：16.44(Nuclear Science & Technology)Disassembly of the JT-60U torus was started in 2009 after 18-years D
operations, and was completed in October 2012. The JT-60U torus was featured by the complicated and welded structure against the strong electromagnetic force, and by the radioactivation due to D-D reactions. Since this work is the first experience of disassembling a large radioactive fusion device in Japan, careful disassembly activities have been made. About 13,000 components cut into pieces with measuring the dose rates were removed from the torus hall and stored safely in storage facilities by using a total wokers of 41,000 person-days during 3 years. The total weight of the disassembly components reached up to 5,400 tons. Most of the disassembly components will be treated as non-radioactive ones after the clearance verification under the Japanese regulation in future. The assembly of JT-60SA has started in January 2013 after this disassembly of JT-60U torus.
Sukegawa, Atsuhiko; Niita, Koji*
JAEA-Data/Code 2014-013, 61 Pages, 2014/08
JAEA-Data-Code-2014-013.pdf:34.06MB
The accuracy and efficiency of the PHITS code has been investigated towards the application to the fusion facilities by making comparison between PHITS and MCNP calculation for a simplified cylindrical model, for a 3D detailed model of tokamak fusion device, and for experimental assembly models of accelerator for fusion facilities. It was clarified that the results of neutron and photon spectrum obtained by the PHITS code agree with those of MCNP within statistical errors as far as they use the same cross section library, the same model and the same neutron source for the calculation. Moreover, the results of both codes are consistent each other within statistical errors for the case with the same weight window method as a variance reduction technique.
Tanaka, Tadao; Shimada, Taro; Sukegawa, Takenori
Progress in Nuclear Science and Technology (Internet), 4, p.832 - 835, 2014/04
According to a basic policy of Japan, nuclear power plant sites are allowed to be released from nuclear safety regulations after the plants are decommissioned. It is necessary to confirm that there is no significant radioactivity remaining on the sites, for the site release beforehand. Cobalt 60 is one of the typical radionuclide for nuclear power plants. In the evaluation concept, all of cobalt 60, which is in reality distributed across the area of interest, are assumed to be the single point source located at the furthest position on the surface of the area from a Ge detector. In such a configuration, minimum detectable time was supplied by Monte Carlo calculations, and the minimum detectable time was approximately equal to the actual measurement time of the point source by the Ge detector. These results mean that the proposed evaluation method was reasonable for the conservative evaluation of cobalt 60 remaining in the nuclear power plant sites.
-ray shielding resinsSukegawa, Atsuhiko; Anayama, Yoshimasa*
Progress in Nuclear Science and Technology (Internet), 4, p.627 - 630, 2014/04
Flexible heat-resistant neutron and -ray shielding resins have been developed, which consists of polymer resin with boron powder or FeW powder. The resins were manufactured by a newly agitation technique of only by chemical reaction to Low-Cost radiation shielding resin. The neutron resin will be applied around ports of a vacuum vessel of superconducting tokamak device as an additional shielding material and decreased in an effect on neutron streaming of the device. The -ray resin will be suitable for a collimator to plasma diagnostics.
Nishiyama, Tomokazu; Miyo, Yasuhiko; Okano, Fuminori; Sasajima, Tadayuki; Ichige, Hisashi; Kaminaga, Atsushi; Miya, Naoyuki; Sukegawa, Atsuhiko; Ikeda, Yoshitaka; Sakasai, Akira
JAEA-Technology 2014-006, 30 Pages, 2014/03
JAEA-Technology-2014-006.pdf:4.87MB
JT-60 tokamak device and the peripheral equipment were disassembled so as to be upgraded to the superconducting tokamak JT-60SA. The disassembled components were stored into storage and airtight containers at the radioactive control area. The total weight and the total number of those components are about 1,100 tons and about 11,500 except for large components. Radiation measurements and records of the radioactive components were required one by one under the law of Act on Prevention of Radiation Disease Due to Radioisotopes, etc. for the control of transport and storage from the radioactive control area to the other area. The storage management of the radioactive components was implemented by establishing the work procedure and the component management system by barcode tags. The radioactive components as many as 11,500 were surely and effectively stored under the law. The report gives the outline of the storage of JT-60 radioactive components by the storage containers.
Sukegawa, Atsuhiko
Purazuma, Kaku Yugo Gakkai-Shi, 89(11), p.805 - 809, 2013/11
no abstracts in English
Ishigami, Tsutomu; Sukegawa, Takenori*; Mukai, Masayuki
JAEA-Technology 2013-027, 124 Pages, 2013/10
JAEA-Technology-2013-027.pdf:5.9MB
In order to safely and efficiently implement decommissioning of nuclear installations, it is important to beforehand predict decommissioning project management data (PMD) and to develop a decommissioning plan based on the predicted results. The PMD prediction is made with PMD evaluation equations including model parameters such as unit work activity coefficients. Although model parameter values developed so far include uncertainties, little evaluation of the uncertainties and resulted uncertainties in predicted PMD has been made. However information on the uncertainties is valuable in flexibly studying and developing a decommissioning plan. We therefore studied and evaluated uncertainties in model parameters by analyzing the JPDR decommissioning experience data. This report describes an evaluation method of the model parameter uncertainties and their evaluated results.
Ishigami, Tsutomu; Mukai, Masayuki; Sukegawa, Takenori; Matsubara, Takeshi*
JAEA-Data/Code 2012-023, 83 Pages, 2012/11
JAEA-Data-Code-2012-023.pdf:5.51MB
Verification for site release is one of procedures to confirm termination of decommissioning of nuclear installations. The verification procedure would need to confirm that the radioactive concentration at the site is lower than the criterion value by measurement. Then to efficiently perform the measurement and verification it is one of important issues how to efficiently estimate and evaluate overall spatial radioactivity distribution using a sampling method. For the efficient estimation and evaluation we have applied a Kriging technique which in the geostatistics, and have developed a computer program ESRAD (Estimation of Spatial RadioActivity Distribution). The ESRAD program is designed to support sample selection, calculate a variogram, and estimate a radioactivity distribution for the area concerned. This report describes the Kriging technique, structure and functions of ESRAD, input file format, output examples, execution procedure of ERSAR, and sample run with ESRAD.
Sukegawa, Atsuhiko; Anayama, Yoshimasa*; Okuno, Koichi*; Sakurai, Shinji; Kaminaga, Atsushi
Journal of Nuclear Materials, 417(1-3), p.850 - 853, 2011/10
Times Cited Count：21 Percentile：82.72(Materials Science, Multidisciplinary)A flexible heat resistant neutron shielding material has been developed, which consists of polymer resin with 1 weight % boron. The neutron shielding performance of the developed resin, examined by the 
Cf neutron source is almost the same as that of the polyethylene. The outgas of H, HO, CO and CO from the resin have been measured at 250 C environment. The resin will be applied around the port of the vacuum vessel as an additional shielding material and prevented the effects on the neutron streaming of the superconducting tokamak device such as JT-60SA.
