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Kitagaki, Toru; Krasnov, V.*; Ikeda, Atsushi
Journal of Nuclear Materials, 576, p.154224_1 - 154224_14, 2023/04
Times Cited Count：1 Percentile：53.89(Materials Science, Multidisciplinary)Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2022-071, 123 Pages, 2023/03
JAEA-Review-2022-071.pdf:6.07MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2021, this report summarizes the research results of the "Development of a hybrid method for evaluating the long-term structural soundness of nuclear reactor buildings using response monitoring and damage imaging technologies" conducted in FY2021. The present study aims to develop an evaluation method necessary to obtain a perspective on the long-term structural soundness of accident-damaged reactor buildings, where accessibility to work sites is extremely limited due to high radiation dose rate and high contamination. In FY2021, the first year of the three-year plan, the following research items were undertaken by clarifying specific research methods, setting research directions, making necessary preparations, and conducting some tests and other activities.
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2022-066, 91 Pages, 2023/03
JAEA-Review-2022-066.pdf:5.88MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Study on degradation of fuel debris by combined effects of radiological, chemical, and biological functions" conducted in FY2021. In the project, radiochemists, nuclear chemists, nuclear physicists, material scientists, and environmental biologists are teamed to elucidate the mechanism of the degradation of fuel debris by combined effects of radiological, chemical, and biological functions. In fiscal year 2021, the members of the project team have conducted on the microbial degradation of the simulated fuel debris under 
-ray irradiation, complex formation of pentavalent uranium, construction of microchannel system to detect micro-particles and the simulated fuel debris, sorption of tetravalent elements ...
Hirooka, Shun; Nakamichi, Shinya; Matsumoto, Taku; Tsuchimochi, Ryota; Murakami, Tatsutoshi
Frontiers in Nuclear Engineering (Internet), 2, p.1119567_1 - 1119567_7, 2023/03
Storage of plutonium (Pu)-containing materials requires extremely strict attention in terms of physical safety and material accounting. Despite the emphasized importance of storage management, only a few reports are available in the public, e.g., experience in PuO
storage in the UK and safety standards in the storage of Pu-containing materials in the US. Japan also stores more U-Pu mixed oxide (MOX) mostly in powder form. Adopting an appropriate storage management is necessary depending on the characteristics of MOX items such as raw powder obtained by reprocessing of spent Light Water Reactor fuels, research and development on the remains of fuel fabrication, which can contain organic materials, and dry-recycled powder during fuel fabrication. Stagnation in fuel fabrications and experience in degradation of MOX containers during extended period of storage have led to the review of the storage method in the Plutonium Fuel Development Center in Japan Atomic Energy Agency. The present work discusses the various nuclear materials, storage methods, experience in degradation of containers that occur during storage, and strategies for future long-term storage.
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2022-036, 115 Pages, 2023/01
JAEA-Review-2022-036.pdf:7.15MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Investigation of environment induced property change and cracking behavior in fuel debris" conducted in FY2021. The present study aims to investigate the environment induced property change and cracking behavior in fuel debris from the viewpoints of materials science. The research objective is cracking behavior in fuel debris which is presumed to be influenced by environment during long-term fuel debris processing period. The degradation models will be established to simulate the oxidation and hydrogenation processes possibly occurred at fuel debris. The evolution of phase constitution and the corresponding property change in the simulated fuel debris under various environmental conditions …
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2022-005, 93 Pages, 2022/06
JAEA-Review-2022-005.pdf:6.95MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Study on degradation of fuel debris by combined effects of radiological, chemical, and biological functions" conducted in FY2020. In the project, radiochemists, nuclear chemists, nuclear physicists, material scientists, and environmental biologists are teamed to elucidate the mechanism of the degradation of fuel debris by combined effects of radiological, chemical, and biological functions. In fiscal year 2020, the members of the project team have conducted on the degradation of He ions irradiated simulated fuel debris, complex formation of tetravalent elements, uranium (VI) detection in microchannel, sorption of trivalent elements by iron bearing materials, and microbial degradation by model microorganisms …
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2021-058, 75 Pages, 2022/02
JAEA-Review-2021-058.pdf:4.82MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Investigation of environment induced property change and cracking behavior in fuel debris" conducted in FY2020. The present study aims to investigate the environment induced property change and cracking behavior in fuel debris from the viewpoints of materials science. The research objective is cracking behavior in fuel debris which is presumed to be influenced by environment during long-term fuel debris processing period. The degradation models will be established to simulate the oxidation and hydrogenation processes possibly occurred at fuel debris.
Oda, Chie; Kawama, Daisuke*; Shimizu, Hiroyuki*; Benbow, S. J.*; Hirano, Fumio; Takayama, Yusuke; Takase, Hiroyasu*; Mihara, Morihiro; Honda, Akira
Journal of Advanced Concrete Technology, 19(10), p.1075 - 1087, 2021/10
Times Cited Count：0 Percentile：0(Construction & Building Technology)Concrete in a transuranic (TRU) waste repository is considered a suitable material to ensure safety, provide structural integrity and retard radionuclide migration after the waste containers fail. In the current study, coupling between chemical, mass-transport and mechanical, so-called non-linear processes that control concrete degradation and crack development were investigated by coupled numerical models. Application of such coupled numerical models allows identification of the dominant non-linear processes that will control long-term concrete degradation and crack development in a TRU waste repository.
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2020-046, 69 Pages, 2021/01
JAEA-Review-2020-046.pdf:4.81MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Study on Degradation of Fuel Debris by Combined Effects of Radiological, Chemical, and Biological Functions". In the project, radiochemists, nuclear chemists, nuclear physicists, material scientists, and environmental biologists are teamed to elucidate the mechanism of the degradation of fuel debris by combined effects of radiological, chemical, and biological Functions. In FY2019, the members of the project team focused on literature survey, preliminary experiments, and installation of experimental devices for the planned research.
Liu, J.; Dotsuta, Yuma; Kitagaki, Toru; Kozai, Naofumi; Yamaji, Keiko*; Onuki, Toshihiko
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 2 Pages, 2019/05
To decommission the Fukushima Daiichi Nuclear Power Plant (FDNPP), it is necessary to estimate the current status of fuel debris and predicate the possible change under various condition. Some microorganisms may enter the plant due to the seawater injection after accident and future defueling activity. In this study, microbial influence on fuel debris under aerobic condition was experimentally investigated. By culturing some bacteria in the presence of simulant fuel debris in liquid medium, the microbial degradation of fuel debris was observed.
Chai, P.; Yamashita, Susumu; Nagae, Yuji; Kurata, Masaki
Proceedings of 9th Conference on Severe Accident Research (ERMSAR 2019) (Internet), 14 Pages, 2019/03
In order to obtain a precise understanding of molten material behavior inside RPV and to improve the accuracy of the SA code, a new computational fluid dynamics (CFD) code with multi-phase, multi-physics models, which is called JUPITER, was developed. It optimized the algorithms of the multi-phase calculation. Besides, the chemical reactions are also modeled carefully in the code so that the melting process could be treated precisely. A series of verification and validation studies are conducted, which show good agreement with analytical solutions and previous experiments. The capabilities of the multi-physics models in JUPITER code provide us another useful tool to investigate the molten material behaviors in the relevant severe accident scenario.
Ochs, M.*; Vriens, B.*; Tachi, Yukio
Progress in Nuclear Science and Technology (Internet), 5, p.208 - 212, 2018/11
The clean-up activities related to the accident at the Fukushima Nuclear Power Plant give rise to several types of wastes containing cementitious materials, such as concrete. Further, the use of cement-based barriers may be considered, due to their favorable and stable chemical properties, including their ability to sorb or incorporate radionuclides. Wastes from Fukushima are expected to contain substances that can have perturbing effects on retention, especially organic complexing substances, boron, and chloride salts. The present study focuses on a methodology for quantifying the retention behaviour of UVI) and U(IV) in cement materials of different degradation and in the presence of organics, boron, and salts on the basis of available literature information. A stepwise approach is proposed and illustrated for Kd setting for U(VI) and U(IV).
Nagase, Fumihisa; Sakamoto, Kan*; Yamashita, Shinichiro
Corrosion Reviews, 35(3), p.129 - 140, 2017/08
Times Cited Count：13 Percentile：50.97(Electrochemistry)As the lessons learnt from the accident at the Fukushima Daiichi Nuclear Power Station, advanced cladding materials are being developed to enhance accident tolerance comparing with conventional zirconium alloys. The present paper reviews the progress of the development and summarizes subjects to be solved for the enhanced accident-tolerance fuel cladding, focusing on performance degradation under various corrosive environmental conditions that should be considered in designing the LWR fuel.
Watanabe, So; Sano, Yuichi; Kofuji, Hirohide; Takeuchi, Masayuki; Koizumi, Tsutomu
NEA/NSC/R(2015)2 (Internet), p.338 - 344, 2015/06
-ray irradiation in zeolite/water mixturesKumagai, Yuta
Hoshasen Kagaku (Internet), (99), p.53 - 56, 2015/04
Radiation-induced degradation of 2-chlorophenol (2-ClPh) in zeolite/water mixtures was studied in order to consider a possibility of adsorption on zeolites to improve efficiencies of irradiation treatments of water contaminated by organic compounds. The degradation of 2-ClPh by -ray irradiation was investigated as a model compound. The degradation was evaluated by chloride ion (Cl
) production. A high concentration of Cl was observed after the irradiation of a mixture with a mordenite-type zeolite (NaMOR), whereas A-type and X-type zeolites showed no significant effect. Therefore, for the mixture with NaMOR, effects of pH of the solution and of the 2-ClPh concentration were examined. At pH 5.7, the excess production of Cl was induced by the addition of NaMOR. Concurrently, adsorption of 2-ClPh on NaMOR was observed. When the mixture contained a higher concentration of 2-ClPh at pH 5.7, the Cl production increased. The adsorption of 2-ClPh also increased with increasing concentration. The results suggest that organics adsorbed on zeolites are decomposed by irradiation effectively at high adsorption concentrations.
C control rod in severe accident of LWRShirasu, Noriko; Kurata, Masaki; Ogawa, Toru*
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 6 Pages, 2014/09
In the accident of Fukushima-Daiichi Nuclear Power Plant, degraded fuels containing Zircaloy probably reacted with BC control blades containing stainless steel cladding or blade sheath. Since light elements like B and C are able to react easily with various elements and form various chemical species, several concerns are pointed out, such as variation in volatility and heat generation by oxidation of B and C. The chemical states of degraded fuel were evaluated on the assumption of thermodynamic equilibrium under various conditions of oxygen potential and temperature. The chemical behavior of B affects significantly the variation in oxygen potential with progressing severe accident, and many kinds of volatile compounds are formed by oxidation. The behavior of B causes the changes of volatility of FPs, such as Sr, Cs and Mo.
-mode plasmas in JT-60U tokamakUrano, Hajime; Takizuka, Tomonori; Takenaga, Hidenobu; Oyama, Naoyuki; Miura, Yukitoshi; Kamada, Yutaka
Nuclear Fusion, 46(8), p.781 - 787, 2006/08
Times Cited Count：22 Percentile：58.85(Physics, Fluids & Plasmas)The degradation of energy confinement with increased toroidal beta 
was shown by the non-dimensional analysis in JT-60U. The dependence of the energy confinement on was examined by both the JT-60U ELMy 
-mode confinement database and the dedicated experiment on a single scan while 
and 
were kept fixed as well as the other magnetic geometrical parameters. In both cases, the degradation of energy confinement with increasing was observed, satisfying the relation of 
. This dependence is a little weaker than that predicted by the IPB98(y,2) scaling. The fusion power production rate was estimated to increase in proportion to 
.
Koizumi, Norikiyo; Nunoya, Yoshihiko; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 16(2), p.831 - 834, 2006/06
Times Cited Count：24 Percentile：70.73(Engineering, Electrical & Electronic)no abstracts in English
Sn strand subjected to bending strainHirohashi, Masayuki*; Murakami, Haruyuki*; Ishiyama, Atsushi*; Ueda, Hiroshi*; Koizumi, Norikiyo; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 16(2), p.1721 - 1724, 2006/06
Times Cited Count：9 Percentile：46.66(Engineering, Electrical & Electronic)To demonstrate the applicability of NbSn CICCs to ITER, four NbSn model coils have been constructed and tested. The experimental results showed that the measured critical current (Ic) degraded. In addition, the larger is the applied electromagnetic force, the larger the magnitude of the degradation is. The degradation in n-value was also observed. One of the explanations of this degradation is a local strand bending. This consideration has been supported by the test results. However, general dependence of Ic on periodic bending strain has not been clarified in this test since the experiments were carried out at a certain magnetic field, temperature and strain. Therefore, a numerical simulation code was developed to study the general dependence of the Ic and n-value of the NbSn strand on periodic bending strain. A distributed constant circuit model is applied to simulate current transfer among the filaments in the strand. The simulation results show relatively good agreement with the experiment results but some modification in modeling is required for more accurate simulation.
Nankawa, Takuya; Suzuki, Yoshinori*; Ozaki, Takuo; Onuki, Toshihiko; Francis, A. J.*
Journal of Alloys and Compounds, 408-412, p.1329 - 1333, 2006/02
Times Cited Count：3 Percentile：28.65(Chemistry, Physical)We studied the biodegradation of Eu(III)-malic acid complexes by . Ten milimolar Malic acid was degraded in the absence and in the presence of Eu(III) of 0.05, 0.1, and 0.2 mM. The degradation rate of malic acid increased with decreasing the ratios of Eu(III) to malic acid. These results suggest that the toxicity of Eu(III) can be masked through its complexation with malic acid. The degradation of malic acid was followed by the production of unidentified metabolites which were associated with Eu(III). One of the unidentified organic acids was analysed to be pyruvic acid. Our findings suggest that metabolites can influence the environmental behavior of Eu(III) by biologically transformed through subsequent complexation with Eu(III).
