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Journal Articles

Phase-field model for crystallization in alkali disilicate glasses; Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$

Kawaguchi, Munemichi; Uno, Masayoshi*

Journal of the Ceramic Society of Japan, 128(10), p.832 - 838, 2020/10

 Times Cited Count:0

This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient ($$L$$). The crystal growth rates ($$v_0$$) obtained by the PFM calculation with the constant $$L$$ were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the $$L$$ was determined from the experimental crystal growth rates and the $$v_0$$. Using the determined $$L$$, the crystal growth rates ($$v$$) in alkali disilicate glasses, Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$ were simulated. The temperature dependence of the $$v$$ was qualitatively and quantitatively so similar that the PFM calculation results demonstrated the validity of the $$L$$. Especially, the $$v$$ obtained by the PFM calculation appeared the rapid increase just below the thermodynamic melting point ($$T_{rm m}$$) and the steep peak at around $$T_{rm m}$$-100 K. Additionally, as the temperature decreased, the $$v$$ apparently approached zero ms$$^-1$$, which is limited by the $$L$$ representing the interface jump process. Furthermore, we implemented the PFM calculation for the variation of the parameter $$B$$ in the $$L$$. As the $$B$$ increased from zero to two, the peak of the $$v$$ became steeper and the peak temperature of the $$v$$ shifted to the high temperature side. The parameters $$A$$ and $$B$$ in the $$L$$ increased exponentially and decreased linearly as the atomic number of the alkali metal increased due to the ionic potential, respectively. This calculation revealed that the $$A$$ and $$B$$ in the $$L$$ were close and reasonable for each other.

JAEA Reports

Assessment report on research and development activities in FY2019; Activity "Research and development on high temperature gas-cooled reactor and related heat application technology" (Interim report)

Sector of Fast Reactor and Advanced Reactor Research and Development

JAEA-Evaluation 2020-001, 128 Pages, 2020/08


Japan Atomic Energy Agency consulted with the "Evaluation Committee of Research Activities for High Temperature Gas-cooled Reactor (hereinafter referred to as "HTGR") and Related Hydrogen Production Technology" (hereinafter referred to as "Evaluation Committee"), which consists of specialists in the fields of the evaluation subjects of high temperature gas-cooled reactor and related heat application technology, for interim assessment in the 3rd Mid-and Long-Term Plan about the relevance of the management and research activities of the HTGR and related application technology during the period from April 2017 to March 2020. As a result, three members of the Evaluation Committee concluded a score of "S", and seven members of the Evaluation Committee concluded a score of "A". The interim assessment to research and development activities from April 2017 to March 2020 was concluded a score of "A". In addition, the Evaluation Committee recommended that the judgement to move to the construction phase of the HTTR-heat utilization test plant be made after 2 years, after the HTTR will be restarted and the thermal load fluctuation tests using HTTR will be carried out. This report lists the members of the Evaluation Committee and outlines the assessment item and the review process for procedure of the assessment. The assessment report which was issued by the Evaluation Committee is attached.

Journal Articles

Corrosion property of container using hybrid material for thermal decomposition process of sulfuric acid

Ioka, Ikuo; Kuriki, Yoshiro*; Iwatsuki, Jin; Kawai, Daisuke*; Yokota, Hiroki*; Inagaki, Yoshiyuki; Kubo, Shinji

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 5 Pages, 2020/08

A thermochemical water-splitting iodine-sulfur processes (IS process) is one of candidates for the large-scale production of hydrogen using heat from solar power. Severe corrosive environment which is thermal decomposition of sulfuric acid exists in the IS process. A hybrid material with the corrosion-resistance and the ductility was made by a plasma spraying and laser treatment. The specimen had excellent corrosion resistance in the condition of 95 mass% boiling sulfuric acid. This was attributed to the formation of SiO$$_{2}$$ on the surface. The container using the hybrid material was experimentally made. The pre-oxidized container using hybrid technique was prepared for the corrosion test in boiling sulfuric acid to evaluate the corrosion characteristics of the container. There was no detaching of the surface with the weld part and the R processing. We proposed the calculation method of corrosion rate from the ions dissolved in the sulfuric acid solution after the corrosion test.

JAEA Reports

Analysis of debris samples of Tokyo Electric Power Company Holdings Fukushima Daiichi Nuclear Power Station

Task Force on Research Strategy for Debris of Fukushima Daiichi Nuclear Power Station

JAEA-Review 2020-004, 140 Pages, 2020/05


Design, planning and control of debris-related processes, namely retrieval, storage management, processing and disposal of the debris, are required for the safe and steady decommissioning of Fukushima Daiichi Nuclear Power Station (1F). Status inside primary containment vessel of 1F must be known by the PCV investigation and fuel debris sample analysis. Continuous updating and improvement of the process design are important through ascertainment of the cause of the accident. The roadmap for the 1F decommissioning have shown the milestone of commencement of trial retrieval of fuels debris within 2021, which indicates the analysis of fuel debris sample begin in earnest. This report recommends required debris analysis in relation with issues for the retrieval, storage management, processing and disposal, and ascertainment of the cause of the 1F accident. Practical analysis plan is expected to be prepared based on this report.

JAEA Reports

Analysis of microparticles generated by laser processing and development of a methodology for their nuclear identification (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2019-034, 59 Pages, 2020/03


JAEA/CLADS, conducted the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aimed to contribute to solving problems in the field of nuclear energy represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development was promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barriers of conventional organizations and research fields. Among the adopted proposals in FY2018, this report summarizes the research results of the "Analysis of microparticles generated by laser processing and development of a methodology for their nuclear identification". Although laser processing has various advantages, one well-known disadvantage is that it generates a large amount of microparticles during the processing. Therefore, the application of laser processing to decommissioning waste contaminated with radioactive materials has been hesitant because the mechanism generating the microparticles has not been fully understood. In this study, the mechanism of microparticle production by laser processing is investigated from fundamentals. Also, we develop a laser on-line principle device to examine the nuclides present in the microparticles that are produced, based on the measurement of the particle size distribution by collecting the microparticles using aerodynamic lenses.

Journal Articles

Contribution of membrane technology to hydrogen society; Development of membrane IS process

Inagaki, Yoshiyuki; Sakaba, Nariaki; Tanaka, Nobuyuki; Nomura, Mikihiro*; Sawada, Shinichi*; Yamaki, Tetsuya*

Nippon Kaisui Gakkai-Shi, 73(4), p.194 - 202, 2019/08

The thermochemical IS process is a promising hydrogen production method which can produce hydrogen in a large amount and stably with high efficiency by thermal splitting of water. Research and development on chemical reaction technology with membranes was conducted for the purpose of improving the efficiency of IS process and application of solar heat. The basic technology of ceramic membranes applied to decomposition reactions of hydrogen iodine and sulfuric acid was developed, and it is expected that the conversion rate on decomposition in each reaction can be remarkably improved. The basic technology of a cation exchange membrane applied to Bunsen reaction was developed with radiation-induced grafting technique, it is expected that the amount of iodine can be reduced to about one-fifth compared to the conventional method. These achievements are important technologies for practical use of the IS process.

Journal Articles

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

 Times Cited Count:6 Percentile:29.77(Chemistry, Physical)

Journal Articles

R&D status of hydrogen production test using IS process test facility made of industrial structural material in JAEA

Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Tanaka, Nobuyuki; Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji

International Journal of Hydrogen Energy, 44(25), p.12583 - 12592, 2019/05

 Times Cited Count:1 Percentile:83.09(Chemistry, Physical)

JAEA has been conducting R&D on thermochemical water-splitting hydrogen production IS process to develop one of heat applications of high-temperature gas-cooled reactor. A test facility was constructed using corrosion-resistant industrial materials to verify integrity of the IS process components and to demonstrate continuous and stable hydrogen production. The performance of components installed in each section was confirmed. Subsequently, a trial operation of integration of the processing sections was successfully carried out for 8 hours with hydrogen production rate of approximately 10 NL/h. After that, hydrogen production operation was extended to 31 hours (approximately hydrogen production rate of 20 NL/h) by introducing a corrosion-resistance pump system with a developed shaft seal technology.

Journal Articles

Module design of silica membrane reactor for hydrogen production via thermochemical IS process

Myagmarjav, O.; Tanaka, Nobuyuki; Nomura, Mikihiro*; Kubo, Shinji

International Journal of Hydrogen Energy, 44(21), p.10207 - 10217, 2019/04

 Times Cited Count:5 Percentile:36.23(Chemistry, Physical)

Journal Articles

Measurement of $$^{73}$$Ge(n,$$gamma$$) cross sections and implications for stellar nucleosynthesis

Lederer-Woods, C.*; Battino, U.*; Ferreira, P.*; Gawlik, A.*; Kimura, Atsushi; n_TOF Collaboration*; 128 of others*

Physics Letters B, 790, p.458 - 465, 2019/03

 Times Cited Count:1 Percentile:60.45(Astronomy & Astrophysics)

Journal Articles

Model intercomparison of atmospheric $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10

 Times Cited Count:9 Percentile:29.71(Meteorology & Atmospheric Sciences)

A model intercomparison of the atmospheric dispersion of $$^{137}$$Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of $$^{137}$$Cs in the atmosphere. The same meteorological data, horizontal grid resolution, and an emission inventory were applied to all the models to focus on the model variability originating from the processes included in each model. The multi-model ensemble captured 40% of the observed $$^{137}$$Cs events, and the figure-of-merit in space for the total deposition of $$^{137}$$Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the $$^{137}$$Cs events. The results also revealed that the differences among the models were originated from the deposition and diffusion processes when the meteorological field was simulated well. However, the models with strong diffusion tended to overestimate the $$^{137}$$Cs concentrations.

Journal Articles

Demonstration of $$gamma$$-ray pipe-monitoring capabilities for real-time process monitoring safeguards applications in reprocessing facilities

Rodriguez, D.; Tanigawa, Masafumi; Nishimura, Kazuaki; Mukai, Yasunobu; Nakamura, Hironobu; Kurita, Tsutomu; Takamine, Jun; Suzuki, Satoshi*; Sekine, Megumi; Rossi, F.; et al.

Journal of Nuclear Science and Technology, 55(7), p.792 - 804, 2018/07

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Nuclear material in reprocessing facilities is safeguarded by random sample verification with additional continuous monitoring applied to solution masses and volume in important tanks to maintain continuity-of-knowledge of process operation. Measuring the unique $$gamma$$ rays of each solution as the material flows through pipes connecting all tanks and process apparatuses could potentially improve process monitoring by verifying the compositions in real time. We tested this $$gamma$$ ray pipe-monitoring method using plutonium-nitrate solution transferred between tanks at the PCDF-TRP. The $$gamma$$ rays were measured using a lanthanum-bromide detector with a list-mode data acquisition system to obtain both time and energy of $$gamma$$-ray. The analysis and results of this measurement demonstrate an ability to determine isotopic composition, process timing, flow rate, and volume of solution flowing through pipes, introducing a viable capability for process monitoring safeguards verification.

Journal Articles

The Development status of Generation IV reactor systems, 2; High temperature gas-cooled reactor (HTGR)

Kunitomi, Kazuhiko; Nishihara, Tetsuo; Yan, X.; Tachibana, Yukio; Shibata, Taiju

Nippon Genshiryoku Gakkai-Shi, 60(4), p.236 - 240, 2018/04

High temperature gas-cooled reactor (HTGR) is a graphite-moderated and helium-gas-cooled thermal-neutron reactor that has excellent safety features and can produce high temperature heat of 950$$^{circ}$$C. It is expected to use for various heat applications as well as for electricity generation to reduce carbon dioxide emission. Japan Atomic Energy Agency (JAEA) has been promoted research and development to demonstrate the HTGR safety features using High temperature engineering test reactor (HTTR) and it's heat application. JAEA are also conducting the action to international deployment of Japanese HTGR technologies in cooperation with industries-government-academia. This paper reports status of the research and development of HTGR and domestic and international collaborations.

Journal Articles

Application of Bayesian approaches to nuclear reactor severe accident analysis

Zheng, X.; Tamaki, Hitoshi; Shiotsu, Hiroyuki; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 11 Pages, 2017/11

Journal Articles

Industry development activities and applied laser research activities at Fukui branch of Japan Atomic Energy Agency

Furusawa, Akinori; Takenaka, Yusuke*; Nishimura, Akihiko; Mizutani, Haruki; Muramatsu, Toshiharu

Nippon Hozen Gakkai Dai-14-Kai Gakujutsu Koenkai Yoshishu, p.479 - 480, 2017/08

Industry development activities on applied laser research held at Fukui branch of Japan Atomic Energy Agency are reported. Industry development is inevitable in long-term vision and strategy for developing maintenance technology and establishing decommissioning technology. Fukui branch of JAEA has organized public seminar offering businesses to promote these activities and technology exchange for years. Here some examples offered in the current seminar are introduced concerning with laser technology. Finally, our goal and important point of view are discussed.

Journal Articles

Bayesian optimization analysis of containment-venting operation in a Boiling Water Reactor severe accident

Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu

Nuclear Engineering and Technology, 49(2), p.434 - 441, 2017/03

 Times Cited Count:1 Percentile:79.72(Nuclear Science & Technology)

Journal Articles

IS process hydrogen production test for components and system made of industrial structural material, 2; H$$_{2}$$SO$$_{4}$$ decomposition, HI distillation, and HI decomposition section

Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Tanaka, Nobuyuki; Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.1029 - 1038, 2016/11

JAEA has been conducting R&D on the IS process for nuclear-powered hydrogen production. We have constructed a 100 NL/h-H$$_2$$-scale test apparatus made of industrial materials. At first, we investigated performance of components in this apparatus. In this paper, the test results of H$$_2$$SO$$_4$$ decomposition, HI distillation, and HI decomposition were shown. In the H$$_2$$SO$$_4$$ section, O$$_2$$ production rate is proportional to H$$_2$$SO$$_4$$ feed rate and SO$$_3$$ decomposition ratio was estimated about 80%. In HI distillation section, we confirmed to acquire a concentrated HI solution over azeotropic HI composition in the condenser. In HI decomposition section, H$$_2$$ could be produced stably by HI decomposer and decomposition ratio was about 18%. The H$$_2$$SO$$_4$$ decomposer, the HI distillation column, and the HI decomposer were workable. Based on the results added to that shown in Series I, we conducted a trial continuous operation and succeeded it for 8 hours.

Journal Articles

IS process hydrogen production test for components and system made of industrial structural material, 1; Bunsen and HI concentration section

Tanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Iwatsuki, Jin; Aita, Hideki; Kasahara, Seiji; Kubo, Shinji

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.1022 - 1028, 2016/11

Japan Atomic Energy Agency (JAEA) has manufactured 100 NL/h-H$$_2$$-scale hydrogen test apparatus. In advance to conduct the continuous operation, we investigated performance of the components in each section of the IS process. In this paper, the results of test of Bunsen and HI concentration sections was shown. In Bunsen reaction, section, we confirmed that outlet gas flow rate included no SO$$_{2}$$ gas, indicating that all the feed SO$$_{2}$$ gas was absorbed to the solution in the Bunsen reactor for the Bunsen reaction. On the basis of these results, we evaluated that Bunsen reactor was workable. In HI concentration section, HI concentration was conducted by EED stack. As a result, it can concentrate HI in HIx solution as theoretically predicted on the basis of the previous paper. Based on the results added to that shown in Series II, we have conducted a trial continuous operation and succeeded it for 8 hours.

Journal Articles

Bayesian optimization analysis of containment venting operation in a BWR severe accident

Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of 13th Probabilistic Safety Assessment and Management Conference (PSAM-13) (USB Flash Drive), 10 Pages, 2016/10

Journal Articles

Release of radioactive materials from high active liquid waste in small-scale hot test for boiling accident in reprocessing plant

Yamane, Yuichi; Amano, Yuki; Tashiro, Shinsuke; Abe, Hitoshi; Uchiyama, Gunzo; Yoshida, Kazuo; Ishikawa, Jun

Journal of Nuclear Science and Technology, 53(6), p.783 - 789, 2016/06

 Times Cited Count:3 Percentile:56.53(Nuclear Science & Technology)

The release behavior of radioactive materials from high active liquid waste (HALW) has been experimentally investigated under boiling accident conditions. In the experiments using HALW obtained through laboratory scale reprocessing, release ratio was measured for the FP nuclides such as Ru, $$^{99}$$Tc, Cs, Sr, Nd, Y, Mo, Rh and actinides such as $$^{242}$$Cm, $$^{241}$$Am. As a result, the release ratio was 0.20 for Ru and 1$$times$$$$10^{-4}$$ for the FP and Ac nuclides. Ru was released into the gas phase in the form of both mist and gas. For its released amount, weak dependency was found to the initial concentration in the test solution. The release ratio decreased with the initial concentration. For other FP nuclides and actinides as non-volatile, released into the gas phase in the form of mist, the released amount increased with the initial concentration. The release ratio of Ru and NOx concentration increased with temperature of the test solutions. They were released almost at the same temperature between 200 and 300$$^{circ}$$C. Size distribution of the mist and other particle was measured.

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