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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.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2022, P. 73, 2023/07
The present study is concerned with the neutron capture cross-sections that contribute to the evaluation of the amount of radionuclides possessing problems in decommissioning. In this study, 
Sc, 
Cu, 
Zn, 
Ag, 
In and 
W were selected among the objective nuclides, and their thermal-neutron capture cross-sections were measured using TC-Pn equipment of the KUR of the Institute for Integrated Radiation and Nuclear Science, Kyoto University. High purity metal samples were prepared. A gold-aluminum ally wire, cobalt and molybdenum foils were used to monitor the neutron flux at the irradiation position of TC-Pn. The flux monitors and metal samples were irradiated for 1 hour at 1-MW operation of the KUR. After irradiation, the irradiation capsule was opened, samples and flux monitors were enclosed in a vinyl bag one by one, and then 
rays emitted from the samples and monitors were measured with a high-purity Ge detector. The thermal-neutron flux component was derived with the reaction rates of flux monitors (
Au, 
Co and 
Mo) on the basis of Westcott's convention, and found to be (5.92
0.10)
10
n/cm
/sec at the irradiation position. The measured reaction rate for each metal sample divided by the evaluated thermal-neutron capture cross-section should give the same value of the thermal-neutron flux component if the cross section is suitable. This time, we found that the cross sections of Sc and 
Zn were consistent with the evaluated one, but those of other nuclides were inconsistent with their evaluated ones; that is, it turned out that their thermal-neutron capture cross-sections should be modified.
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.
Shimada, Taro; Nemoto, Hiromi*; Takeda, Seiji
Hoken Butsuri (Internet), 57(1), p.5 - 29, 2022/03
Of the asbestos-containing wastes arising from the dismantling activities of nuclear facilities, those with radioactive concentrations that do not need to be treated as radioactive substances will be cleared from the nuclear regulatory control. Those will be disposed of or recycled as specially controlled industrial waste based on the Waste Management and Public Cleansing Act. The authors constructed evaluation scenarios according to the treatment manual for asbestos-containing waste and evaluated public exposure doses per year for 33 radionuclides. Based on the evaluated doses, the radioactive concentration corresponding to the dose criteria of 10 
Sv/y for clearance was calculated for each radionuclide and scenario. As a result, the evaluated concentration was equal to or higher than the current clearance level. It was confirmed that the application of the current clearance level for asbestos-containing wastes did not affect safety.
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.
Nakamura, Yasuyuki; Koda, Yuya; Yamamoto, Kosuke; Soejima, Goro; Iguchi, Yukihiro
JAEA-Review 2020-002, 40 Pages, 2020/05
JAEA-Review-2020-002.pdf:8.78MB
Fugen Decommissioning Engineering Center, in planning and carrying out our decommissioning technical development, has been establishing "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 inside and outside the country, as the central point in the energy research and development base making project of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report compiles presentation materials "The Current Situation of Fugen Decommissioning", "Development of Dismantling Mon-hours Estimated system by Achieved Data in Fugen", "Future Plan Based on the Operational Status of Clearance System" and "The Result and Future Plan of the Sampling work from Core Internal of Fugen", presented in the 37th Technical special committee on Fugen decommissioning which was held on December 2, 2019.
Sugaya, Toshikatsu; Nakatani, Takayoshi; Sasaki, Toshihisa*; Nakamura, Yasuo*; Sakai, Akihiro; Sakamoto, Yoshiaki
JAEA-Technology 2016-036, 126 Pages, 2017/02
JAEA-Technology-2016-036.pdf:7.28MB
At the Radioactive Waste Management and Disposal Project Department Sector of Decommissioning and Radioactive Waste Management, we performed the technological study about the disposal measures of the low-level radioactive waste targeted for uranium-bearing waste and intermediate depth disposal-based waste occurring from the process of the nuclear fuel cycle.
Hayashi, Hirokazu; Soejima, Goro; Mizui, Hiroyuki; Sano, Kazuya
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
In the Fugen Nuclear Power Plant, we are going to conduct appropriate classification of the waste according to the contamination level of the material of the plant, to reduce the amount of radioactive waste and to promote dismantling work rationally and efficiently. For this reason, we are going to apply the clearance system to the dismantled material generated from dismantling work of the turbine system, and to reduce the radioactive waste amount as much as possible. In order to operate the clearance system properly, the target nuclides need to be selected accurately, and the evaluation method of them should be established. The assessment was conducted as follows.
Tomii, Hiroyuki; Matsuo, Kiyoshi*; Shiraishi, Kunio; Kato, Rokuro; Watabe, Kozo; Higashiyama, Yutaka; Nagane, Satoru*; Hanawa, Yukimitsu*
JAERI-Tech 2005-017, 65 Pages, 2005/03
JAERI-Tech-2005-017.pdf:3.79MB
no abstracts in English
Wakaida, Ikuo; Miyabe, Masabumi
Bunseki, 2004(10), p.585 - 590, 2004/10
no abstracts in English
Tobita, Kenji; Nishio, Satoshi; Konishi, Satoshi*; Jitsukawa, Shiro
Journal of Nuclear Materials, 329-333(Part2), p.1610 - 1614, 2004/08
Times Cited Count：12 Percentile：61.53(Materials Science, Multidisciplinary)no abstracts in English
Kanno, Mitsuhiro*; Takeda, Seiji; Minase, Naofumi; Kato, Hideo; Kimura, Hideo
JAERI-Conf 2004-011, p.131 - 132, 2004/07
no abstracts in English
Yanagihara, Satoshi
Dekomisshoningu Giho, (28), p.2 - 9, 2003/10
Decommissioning of nuclear facilities has been actively progressed in the major member countries participating to OECD/NEA. The NEA has recognized necessity of studying various issues related to decommissioning nuclear facilities and it has made an approach to solve the issues from various ways. In the cooperative program for decommissioning (CPD), information on decommissioning projects has been exchanged among the member countries. In the working party on decommissioning and dismantling (WPDD), recent issues have been studied in terms of regulation, implementation of decommissioning projects and research and development on technologies. Decommissioning cost and regulatory practices were also studies and the reports were published, which will be useful for understanding the present issues on decommissioning in the world. The NEA's activity on decommissioning will be valuable for us to implement decommissioning projects in safe and economical manner in Japan. This report deals with the recent NEA activities on decommissioning.
Takeda, Seiji; Kimura, Hideo
JAERI-Conf 2003-018, p.111 - 112, 2003/10
no abstracts in English
Sakai, Akihiro; Okoshi, Minoru
Radiation Risk Assessment Workshop Proceedings, p.175 - 186, 2003/00
To establish the clearance levels, the Nuclear Safety Commission (NSC) has been discussing the clearance levels since May 1997. The NSC derived the unconditional clearance levels for the solid materials, namely concrete and metal, arising from the operation and dismantling of nuclear reactors and post irradiation examination (PIE) facilities. Two destinations of the cleared materials, namely disposal and recycle/reuse, were considered. Deterministic calculation models were established to assess individual doses resulting from 73 exposure pathways, and realistic parameter values were selected considering the Japanese natural and social conditions. The clearance levels for 21 radionuclides of nuclear reactors and for 49 of PIE facilities were derived as radioactivity concentration equivalent to the individual doses of 10 Sv/y. Most of calculated clearance levels were nearly the same as those shown in IAEA-TECDOC-855. Some, however, were different. It is considered that the major reasons depend on differences of fixed scenarios and of selected values of parameters.
Okamoto, Akiko; Kitami, Yasuo*; Ando, Yoshiaki*; Nakamura, Hisashi; Saito, Kimiaki; Nakashima, Mikio
JAERI-Tech 2002-051, 40 Pages, 2002/06
JAERI-Tech-2002-051.pdf:3.63MB
In order to contribute to safety assessment of recycling products made from dismantling metal wastes, metal ingots containing 
Co were produced and spatial dose rates from the ingots were evaluated by gamma-ray measurement and calculation. Stripping operations were made using detector response functions calculated by Monte Carlo program to derive spatial dose rates from measured gamma-ray spectra. In the computer simulation, Monte Carlo and point kernel calculation codes were used. Agreement between measured and calculated values was satisfactory in spite of an extremely low concentration of Co in the ingots and a complicated geometric condition between detector and samples.
Tobita, Kenji; Konishi, Satoshi; Nishio, Satoshi; Kosako, Kazuaki*; Tabara, Takashi*
Purazuma, Kaku Yugo Gakkai-Shi, 77(10), p.1035 - 1039, 2001/10
no abstracts in English
Okoshi, Minoru
KURRI-KR-56, p.39 - 57, 2001/03
no abstracts in English
Okoshi, Minoru
Hoken Butsuri, 34(4), p.353 - 358, 1999/12
no abstracts in English
Okoshi, Minoru; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki; Takahashi, Tomoyuki; Kimura, Hideo
Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 8 Pages, 1999/09
no abstracts in English
