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CNguyen, B. V. C.*; Murakami, Kenta*; Chena, L.*; Phongsakorn, P. T.*; Chen, X.*; Hashimoto, Takashi; Hwang, T.*; Furusawa, Akinori; Suzuki, Tatsuya*
Nuclear Materials and Energy (Internet), 39, p.101639_1 - 101639_9, 2024/06
Sato, Yuji; Miyamoto, Yuta; Awatani, Yuto; Yamamoto, Kosuke; Hatakeyama, Takumi
JAEA-Review 2023-002, 59 Pages, 2023/08
JAEA-Review-2023-002.pdf:8.75MB
"Fugen Decommissioning Engineering Center", in planning and carrying out our decommissioning technical development, organizes "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened domestic and international, as the central place in research and development base of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report consists of presentation paper are "Achievements and Considerations for Sampling and Analysis of Reactor Core Components", "Treatment of liquid scintillator waste liquid" and "Results and issues of rationalization of decontamination related to the clearance and considerations related to surface contamination monitoring" which is presented in the 39th Technical Special Committee on Fugen Decommissioning.
Yamamoto, Kosuke; Yanagihara, Satoshi*
Journal of Nuclear Science and Technology, 59(12), p.1527 - 1535, 2022/12
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A series of work activities involved in clearance verification process was analyzed from the viewpoint of work efficiency at Fugen. As a result, decontamination required the most manpower expenditure. In addition, most of clearance candidate materials were very low contamination before the decontamination work. The analysis indicates that it will be effective for these lower radioactivity parts to reduce effort of decontamination activity or to skip the decontamination scenario considering that radioactivity was enough low. In addition, sample monitoring is possible scenario depending on the degree of contamination rather than to monitor all unit for clearance verification. When the manpower is evaluated based on the actual results of Fugen in consideration of these conditions, the clearance verification process could make the efficiency less than 37% in case of Fugen decommissioning.
Ito, Kenji; Kondo, Tetsuo; Nakamura, Yasuyuki; Matsuno, Hiroki; Nagaoki, Yoshihiro; Sakuma, Yuichi
Dekomisshoningu Giho, (63), p.1 - 26, 2022/05
The prototype advanced thermal reactor Fugen entered into the decommissioning phases with the approval of the decommissioning plan in February 2008. The prototype fast breeder reactor Monju entered into the decommissioning stage with the approval of the decommissioning plan in March 2018. In April 2018, the head office of Tsuruga decommissioning demonstration was newly established to oversee the decommissioning operations in Tsuruga area, and decommissioning projects for two unique reactors have progressed safely and steadily.
Sato, Yuji; Yamamoto, Kosuke; Taruta, Yasuyoshi
JAEA-Review 2021-024, 33 Pages, 2021/11
JAEA-Review-2021-024.pdf:5.2MB
"Fugen Decommissioning Engineering Center", in planning and carrying out our decommissioning technical development, organizes "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened domestic and international, as the central place in research and development base of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report consists of presentation materials "The current status of Fugen decommissioning", "Future measures based on clearance decontamination results" and "Fugen decommissioning knowledge management", presented in the 38th Technical Special Committee on Fugen Decommissioning which was held on March 15 to March 26, 2021.
Taruta, Yasuyoshi; Yanagihara, Satoshi*; Hashimoto, Takashi*; Kobayashi, Shigeto*; Iguchi, Yukihiro; Kitamura, Koichi; Koda, Yuya; Tomoda, Koichi
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 8 Pages, 2020/08
Decommissioning is a long-term project during which generations are expected to change. Therefore, it is necessary to appropriately transfer knowledge and technology to the next generation. In recent years, in the world of decommissioning, attempts have been made to apply advanced technologies such as utilization of knowledge management and virtual reality. This study describes adaptation in decommissioning from the viewpoint of utilizing IT technology called digital twin from the viewpoint of knowledge management.
Takiya, Hiroaki; Kadowaki, Haruhiko; Matsushima, Akira; Matsuo, Hidehiko; Ishiyama, Masahiro; Aratani, Kenta; Tezuka, Masashi
JAEA-Technology 2020-001, 76 Pages, 2020/05
JAEA-Technology-2020-001.pdf:6.06MB
Advanced Thermal Reactor (ATR) FUGEN was operated for about 25 years, and now has been proceeding decommissioning after the approval of the decommissioning plan in Feb. 2008. The reactor, heavy water system and helium system are contaminated by tritium because of neutron absorption of heavy water, which is a moderator. Before dismantling these facilities, it is necessary to remove tritium from them for not only reducing the amount of tritium released to surrounding environment and the risk of internal exposure by tritium but also ensuring the workability. In first phase of decommissioning (Heavy Water and Other system Decontamination Period), tritium decontamination of the reactor, heavy water system and helium system started in 2008 and completed in 2018. This report shows the results of tritium decontamination of the reactor, heavy water system and helium system.
Iwai, Hiroki; Soejima, Goro; Takiya, Hiroaki; Awatani, Yuto; Aratani, Kenta; Miyamoto, Yuta; Tezuka, Masashi
Dekomisshoningu Giho, (61), p.12 - 19, 2020/03
FUGEN Decommissioning Engineering Center received the approval of the decommissioning plan in 2008, and we have been progressing the decommissioning. The first phase of decommissioning (Heavy Water and Other System Decontamination Period) finished in March 2018, and FUGEN has entered into the second phase of decommissioning (Reactor Periphery Facilities Dismantling Period). This report outlines the technology demonstration of sampling from reactor core structure of FUGEN that to prepare for reactor dismantlement in the third phase.
Zhao, Q.*; Taruta, Yasuyoshi; Kobayashi, Shigeto*; Hashimoto, Takashi*
Chishiki Kyoso (Internet), 9, p.III 1_1 - III 1_9, 2019/06
no abstracts in English
Riyana, E. S.*; Suda, Shoya*; Ishibashi, Kenji*; Matsuura, Hideaki*; Katakura, Junichi*; Sun, G. M.*; Katano, Yoshiaki
Journal of Nuclear Science and Technology, 56(5), p.369 - 375, 2019/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectra from various reactors such as typical PWR reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta decay.
Takiya, Hiroaki; Aratani, Kenta; Awatani, Yuto; Ishiyama, Masahiro; Tezuka, Masashi; Mizui, Hiroyuki
Dekomisshoningu Giho, (59), p.2 - 12, 2019/03
FUGEN Decommissioning Engineering Center received the approval of the decommissioning program in 2008, and we have been progressing the decommissioning. The first phase of decommissioning (Heavy Water and Other system Decontamination Period) finished in May 2018, and FUGEN has entered into the second phase of decommissioning (Reactor Periphery Facilities Dismantling Period). This report outlines the results obtained in the first phase of decommissioning of FUGEN.
Miki, Naoya*; Harazono, Yuki*; Ishii, Hirotake*; Shimoda, Hiroshi*; Koda, Yuya
International Electronic Journal of Nuclear Safety and Simulation (Internet), 9(2), p.162 - 171, 2018/12
Kyoto University reports on the distance information display system developed in collaboration between "Fugen" and Kyoto University. In the distance information display system, the worker can easily measure the distance of the object. In this presentation, we report the test results carried out with "Fugen" and the questionnaire results of the subjects.
Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Tsuzuki, Satoshi*; Yasunaga, Kazushi*; Kume, Kyo*
Heisei-29-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 20, P. 80, 2018/11
We investigated the behavior of the dust generated by Laser and Plasma-arc cutting underwater and in air aimed at the simulant material of reactor components (SUS304) and the pressure and calandria tube (Zr-2.5%Nb, Zry-2) of the prototype reactor "FUGEN".
Takiya, Hiroaki; Ishiyama, Masahiro; Tezuka, Masashi; Kitayama, Naoki
Proceedings of International Conference on Dismantling Challenges; Industrial Reality, Prospects and Feedback Experience (DEM 2018) (Internet), 8 Pages, 2018/10
In FUGEN, we had isolated the reactor core by cutting pipes of the periphery systems (e.g. reactor cooling system, heavy water system, and helium system) between 2015 and 2017, as preparation for dismantling the reactor core and taking some samples from the reactor core structures. There are three issues to be solved at this isolation work; (1) to shorten the working time at high radiation area which is 1-5mSv/h at air and 10mSv/h at contact, (2) to prevent tritium spreading to working area at cutting work because tritium air is existing with 20-30Bq/cm
inside of the heavy water system and helium system, and (3) to minimize the influence of contaminated fume for the accurate radioactivity evaluation of reactor core structure. In this study, considering these problems, we discussed the method for cutting the pipes of heavy water system and helium system at the high radiation area and carried out the pipe cutting in the way.
Miki, Naoya*; Harazono, Yuki*; Ishii, Hirotake*; Shimoda, Hiroshi*; Koda, Yuya
Proceedings of 2nd International Conference on Computer-Human Interaction Research and Applications (CHIRA 2018) (USB Flash Drive), p.134 - 140, 2018/09
In this study, in order to make measuring lengths of the objects and the gaps at NPPs more efficient, the Distance Information Display System was developed, which make it easy for the dismantling workers to measure them. The results showed that the Distance Information Display System developed in this study can be used easily with extremely simple operation by the dismantling workers at NPPs, and the workers can also measure the lengths in a short time.
Taruta, Yasuyoshi; Yanagihara, Satoshi*; Iguchi, Yukihiro; Kitamura, Koichi; Tezuka, Masashi; Koda, Yuya
Chishiki Kyoso (Internet), 8, p.IV 2_1 - IV 2_12, 2018/08
no abstracts in English
Zhao, Q.*; Taruta, Yasuyoshi; Kobayashi, Shigeto*; Hashimoto, Takashi*
Chishiki Kyoso (Internet), 8, p.V 13_1 - V 13_2, 2018/08
no abstracts in English
Taruta, Yasuyoshi; Yanagihara, Satoshi*; Iguchi, Yukihiro; Kitamura, Koichi; Tezuka, Masashi; Koda, Yuya
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 6 Pages, 2018/07
The IAEA are developed the discussion for those situations and pointed out the importance of nuclear knowledge management. The nuclear knowledge management is developing a database as nuclear knowledge management. In recent years, the IAEA has also advanced knowledge taxonomies on nuclear accidents. These studies are attempts to appropriately arrange and utilize huge amounts of information. Even in nuclear facilities in Japan, it is pointed out that veteran staff aging and loss of knowledge and skill caused by retirement. Therefore, we created a prototype database system to utilize past knowledge and information for ATR Fugen. Now, there are few cases of past decommissioning that can be utilized. This study of pilot model concept revealed that it is not sufficient to just prepare a past data and information. This is what information other than the construction report requires the decommissioning and what kind of information should be gathered.
Tezuka, Masashi; Taruta, Yasuyoshi; Koda, Yuya
Dekomisshoningu Giho, (56), p.46 - 54, 2017/09
Implementation of decommissioning needs much plant information in period of Design, construction and operation. In addition, it is essential for efficient dismantling works to advance the technologies, data, lessons and learns, experiences and documents by getting through the decommissioning process. On the other hands, as workers who operated or maintained the plant are aging and retiring, their empirical knowledge has been lost. For the purpose of safety and reasonability of further decommissioning activities, Knowledge Management System (KMS) has been producing in FUGEN which is now under decommissioning. KMS is an initiative of human resources development and to pass on expertise and knowledge to the younger generations. The system based on the prototype of FUGEN aims a high versatility system available for further decommissioning facilities.
Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Hayashi, Hirokazu; Kadowaki, Haruhiko; Mizui, Hiroyuki; Sano, Kazuya
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07
no abstracts in English
