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Aihara, Jun; Ueta, Shohei; Honda, Masaki*; Kasahara, Seiji; Okamoto, Koji*
JAEA-Research 2024-012, 98 Pages, 2025/02
JAEA-Research-2024-012.pdf:32.24MB
Concept of Pu-burner high temperature gas-cooled reactor (HTGR) was proposed for the purpose of more safely reducing amount of recovered Pu. In Pu-burner HTGR concept, coated fuel particle (CFP), with ZrC coated yttria stabilized zirconia (YSZ) containing PuO
(PuO-YSZ) small particle and with tri-structural isotropic (TRISO) coating, is employed for very high burn-up and high nuclear proliferation resistance. ZrC layer is oxygen getter. In research project of Pu-burner HTGR carried out from fiscal year of 2014 to fiscal year of 2017, simulated CFPs were fabricated using Ce to simulate Pu. Moreover, simulated fuel compacts were fabricated using fabricated simulated CFPs. In this report, results of microstructural observation of CeO-YSZ and ZrC layer at each fabrication step are reported.
Fujita, Tatsuya; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 62(2), p.179 - 196, 2025/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)This study newly established a direct coupling code system consisting of the nuclear data processing code FRENDY version 2, and the three-dimensional heterogeneous transport code GENESIS (FRENDY-V2/GENESIS) for easy implementation of the random-sampling-based uncertainty quantification considering the implicit effect due to nuclear cross-section (XS) perturbations. The multi-group macroscopic XSs prepared for GENESIS were generated by FRENDY version 2, where the Dancoff factor was calculated by the neutron current method. Then the background XSs were evaluated based on the Carlvik two-term rational approximation. The infinite multiplication factor (k-infinity) and the fission reaction rate distribution in UO and MOX lattice geometries were compared with MVP3 to verify the calculation accuracy of FRENDY-V2/GENESIS. The sensitivity analyses on the discretization conditions such as the ray tracing of the method of characteristics were also carried out. Through several comparisons between FRENDY-V2/GENESIS and MVP3, FRENDY-V2/GENESIS with the SHEM 361-group structure calculates the k-infinity within approximately 50 pcm and the fission reaction rate distribution within approximately 0.1% by the root mean square, respectively. Consequently, the applicability of FRENDY-V2/GENESIS was verified, and FRENDY-V2/GENESIS can be used to discuss the implicit effect due to multi-group XS perturbations.
compoundsFrazer, D.*; Saleh, T. A.*; Matsumoto, Taku; Hirooka, Shun; Kato, Masato; McClellan, K.*; White, J. T.*
Nuclear Engineering and Design, 423, p.113136_1 - 113136_7, 2024/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Nanoindentation based techniques can be employed on minute volumes of material to measure mechanical properties, including Young's modulus, hardness, and creep stress exponents. In this study, (U,Ce)O solid solutions samples are used to develop elevated temperature nanoindentation and nanoindentation creep testing methods for use on mixed oxide fuels. Nanoindentation testing was performed on 3 separate (Ux-1,Cex)O compounds ranging from x equals 0.1 to 0.3 at up to 800 
C: their Young's modulus, hardness, and creep stress exponents were evaluated. The Young's modulus decreases in the expected linear manner while the hardness decreases in the expected exponential manner. The nanoindentation creep experiments at 800 C give stress exponent values, n=4.7-6.9, that suggests dislocation motion as the deformation mechanism.
pellet in molten Zr claddingIto, Ayumi*; Yamashita, Susumu; Tasaki, Yudai; Kakiuchi, Kazuo; Kobayashi, Yoshinao*
Journal of Nuclear Science and Technology, 60(4), p.450 - 459, 2023/04
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology) ceramicsVauchy, R.; Hirooka, Shun; Watanabe, Masashi; Yokoyama, Keisuke; Sunaoshi, Takeo*; Yamada, Tadahisa*; Nakamichi, Shinya; Murakami, Tatsutoshi
Ceramics International, 49(2), p.3058 - 3065, 2023/01
Times Cited Count：11 Percentile：67.57(Materials Science, Ceramics)(001) surface with supersonic seeded oxygen molecular beamKatsube, Daiki*; Ono, Shinya*; Inami, Eiichi*; Yoshigoe, Akitaka; Abe, Masayuki*
Vacuum and Surface Science, 65(11), p.526 - 530, 2022/11
The oxidation of oxygen vacancies at the surface of anatase TiO (001) was investigated by synchrotron radiation photoelectron spectroscopy and supersonic O beam (SSMB). The oxygen vacancies at the top surface and subsurface could be eliminated by the supply of hyperthermal oxygen molecules. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the ambient condition, could also be effectively eliminated by using oxygen SSMB. This result is promising as a surface processing for various functional oxides.
and GeO liquidsKawaguchi, Munemichi; Uno, Masayoshi*
Journal of Crystal Growth, 585, p.126590_1 - 126590_7, 2022/05
Phase-field mobility, 
, and crystal growth rates in crystallization of 11 oxides or mixed oxides in undercooled silicates, SiO and GeO liquids were calculated with a simple phase-field model (PFM), and material dependence of the was discussed. Ratios between experimental crystal growth rates and the PFM simulation with 
were confirmed to be proportional to a power of 
on the solid/liquid interface process during the crystal growth in a log-log plot. We determined that parameters, 
and 
, of the 
were 
to 
m
J
s and 
to 
, which were unique for the materials. It was confirmed that our PFM simulation with the determined reproduced quantitively the experimental crystal growth rates. The has a proportional relationship with the diffusion coefficient of a cation molar mass average per unit an oxygen molar mass at 
in a log-log graph. The depends on the sum of the cation molar mass per the oxygen molar mass, 
, in a compound. In 
, the decreases with the cation molar mass increasing. The assumed cause is that the B represents the degree of the temperature dependence of the . Since the cation molar mass is proportional to an inertial resistance of the cation transfer, the decreases with inverse of the cation molar mass. In crystallization of the silicates of heavy cation in 
, the saturates at approximately 0.67, which leads to 
.
-edge EXAFS and magnetic EXAFS studies on the halfmetallic ferromagnet CoMnSiKogo, Junya*; Fujiwara, Hidenori*; Sekiyama, Akira*; Saito, Yuji; Umetsu, Rie*; Niki, Kaori*
Journal of the Physical Society of Japan, 91(3), p.034702_1 - 034702_12, 2022/03
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2021-046, 77 Pages, 2022/01
JAEA-Review-2021-046.pdf:2.92MB
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 FY2018, this report summarizes the research results of the "Development of technology to simultaneously measure viscosity and surface tension of molten materials in reactor core" conducted from FY2018 to FY2020. Since the final year of this proposal was FY2020, the results for three fiscal years were summarized. Since (U, Zr)O and boride, molten materials in reactor core, exist at extremely high temperature, chemical reactions between the vessel and these molten materials are unavoidable. Therefore, it is difficult to measure the thermophysical property of these materials. In the present study, droplets are produced by heating and melting the samples levitated by a gas levitation method, then the droplets are collided with a substrate.
Baba, Yuji*; Shimoyama, Iwao
Chemical Physics, 550, p.111302_1 - 111302_5, 2021/10
Times Cited Count：2 Percentile：10.62(Chemistry, Physical)The effect of a core-to-valence resonant photoexcitation in an atom on photoemission from the neighboring atoms has been experimentally investigated. For SiO fine powder mixed with boron nitride matrix, it was found that the intensity of the O 
photoelectrons was reduced around the Si 
resonant photoexcitation. On the other hand, the intensity of the B or N photoelectrons from the matrix material did not change regardless of the photon energy. Similar phenomenon was also observed for Si
N
powder mixed with cellulose as a matrix material. The results demonstrated that photoemission from the nearest-neighbor atoms that are directly bound to silicon is perturbated by the core-to-valence resonant photoexcitation in silicon. Using the phenomenon, it is expected that species of the nearest neighbor atom can be identified by a resonant core-level excitation in a target atom.
(001) surface using supersonic seeded oxygen molecular beamKatsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
Times Cited Count：3 Percentile：15.23(Chemistry, Multidisciplinary)We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
Hidaka, Akihide
Proceedings of 2021 International Congress on Advances in Nuclear Power Plants (ICAPP 2021) (USB Flash Drive), 10 Pages, 2021/10
Author recently proposed that the Type A glassy Cesium-bearing microparticles that were released during the Fukushima accident may have been formed by melting and atomization of glass fibers of the High Efficiency Particulate Air (HEPA) filter in the Stand-by Gas Treatment System (SGTS) line in Unit 3 during the hydrogen explosion. In the present study, the components of the Type A and glass fibers of HEPA filter were examined using EPMA. The results showed that the components of the Type A were almost the same as that of the glass fibers except for Cs, Fe, Sn, which are considered to have been contained in the in-vessel-derived particles. When the glass fiber was irradiated with the electron beam of the Electron Probe Micro Analyzer (EPMA) under vacuum condition, spherical particles of a few micro m size were formed that looked very similar to the Type A. These strongly suggest that the HEPA filter is Si source of the Type A.
Myagmarjav, O.; Shibata, Ai*; Tanaka, Nobuyuki; Noguchi, Hiroki; Kubo, Shinji; Nomura, Mikihiro*; Takegami, Hiroaki
International Journal of Hydrogen Energy, 46(56), p.28435 - 28449, 2021/08
Times Cited Count：4 Percentile：9.91(Chemistry, Physical)Udagawa, Yutaka; Tasaki, Yudai
JAEA-Data/Code 2021-007, 56 Pages, 2021/07
JAEA-Data-Code-2021-007.pdf:5.05MB
Japan Atomic Energy Agency (JAEA) has released FEMAXI-8 in 2019 as the latest version of the fuel performance code FEMAXI, which has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly normal operation conditions and anticipated transient conditions. This report summarizes a newly developed model to analyze intragranular fission gas behaviors considering size distribution of gas bubbles and their dynamics. While the intragranular fission gas behavior models implemented in the previous FEMAXI versions have supported only treating single bubble size for a given fuel element, the new model supports multiple gas groups according to their size and treats their dynamic behaviors, making the code more versatile. The model was first implemented as a general module that takes arbitrary number of bubble groups and spatial mesh division for a given fuel grain system. An interface module to connect the model to FEMAXI-8 was then developed so that it works as a 2 bubble groups model, which is the minimum configuration of the multi-grouped model to be operated with FEMAXI-8 at the minimum calculation cost. FEMAXI-8 with the new intragranular model was subjected to a systematic validation calculation against 144 irradiation test cases and recommended values for model parameters were determined so that the code makes reasonable predictions in terms of fuel center temperature, fission gas release, etc. under steady-state and power ramp conditions.
Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2020-038, 41 Pages, 2020/12
JAEA-Review-2020-038.pdf:3.28MB
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Technology to Simultaneously Measure Viscosity and Surface Tension of Molten Materials in Reactor Core" conducted in FY2019.
H monitoring in radioactive gaseous wasteFurutani, Misa; Kometani, Tatsunari; Nakagawa, Masahiro; Ueno, Yumi; Sato, Junya; Iwai, Yasunori*
Hoken Butsuri (Internet), 55(2), p.97 - 101, 2020/06
Herein, an oxidation catalyst was introduced after heating it to 600C to oxidize tritium gas (HT) existing in exhaust into tritiated water vapor (HTO). This study aims to establish a safer H monitoring system by lowering the heating temperature required for the catalyst. In these experiments, which were conducted in the Nuclear Science Research Institute, Japan Atomic Energy Agency, cupric oxide, hydrophobic palladium/silicon dioxide (Pd/SiO), and platinum/aluminum oxide (Pt/AlO) catalysts were ventilated using standard hydrogen gas. After comparing the oxidation efficiency of each catalyst at different temperatures, we found that the hydrophobic Pd/SiO and Pt/AlO catalysts could oxidize HT into HTO at 25C.
Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2019-025, 36 Pages, 2020/01
JAEA-Review-2019-025.pdf:2.57MB
CLADS, JAEA, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field 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 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 FY2018, this report summarizes the research results of the "Development of Technology to Simultaneously Measure Viscosity and Surface Tension of Molten Materials in Reactor Core". Since (U,Zr)O and boride, molten materials in reactor core, exist at extremely high temperature, chemical reactions between the vessel and these molten materials are unavoidable. Therefore, it is difficult to measure the thermophysical property of these materials. In the present study, droplets are produced by heating and melting the samples levitated by a gas levitation method, then the droplets are collided with a substrate. From the instant behavior of the collision, a new technology to simultaneously derive the viscosity and surface tension will be developed.
Suzuki, Kiichi; Kato, Masato; Sunaoshi, Takeo*; Uno, Hiroki*; Carvajal-Nunez, U.*; Nelson, A. T.*; McClellan, K. J.*
Journal of the American Ceramic Society, 102(4), p.1994 - 2008, 2019/04
Times Cited Count：52 Percentile：92.70(Materials Science, Ceramics)The fundamental properties of CeO were assessed using a range of experimental techniques. The oxygen potential of CeO was measured by the thermogravimetric technique, and a numerical fit for the oxygen potential of CeO is derived based on defect chemistry. Mechanical properties of CeO were obtained using sound velocity measurement, resonant ultrasound spectroscopy and nanoindentation. The obtained mechanical properties of CeO are then used to evaluate the Debye temperature and Gruneisen constant. The heat capacity and thermal conductivity of CeO were also calculated using the Debye temperature and the Gruneisen constant. Finally, the thermal conductivity was calculated based upon laser flash analysis measurements. This result demonstrates that the thermal conductivity has strong dependence upon material purity.
(am) solubility at 25C in the Ca
-Na
-H-Cl
-OH-HO system; A Critical reviewRai, D.*; Kitamura, Akira; Altmaier, M.*; Rosso, K. M.*; Sasaki, Takayuki*; Kobayashi, Taishi*
Journal of Solution Chemistry, 47(5), p.855 - 891, 2018/05
Times Cited Count：11 Percentile：10.26(Chemistry, Physical)We have critically reviewed experimental data for Zr hydrolysis constant values for formation of several mononuclear and polynuclear species and a solubility product value for ZrO(am). We have determined new/revised values for the formation constants of Zr(OH), Zr(OH)(aq), Zr(OH)
, Zr(OH)
and CaZr(OH)
, and the solubility product for ZrO(am) after the critical review.
Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki
Analytical Methods, 9(44), p.6261 - 6266, 2017/11
Times Cited Count：11 Percentile：59.26(Chemistry, Analytical)A combination of micro-sampling, micro-Raman spectroscopy (MRS), and secondary ion mass spectrometry (SIMS) was applied to the characterization of individual uranium particles. Reference particles with UO
(NBL CRM U010) and UO were identified by scanning electron microscopy combined with energy dispersive X-ray detection (SEM-EDX) and transferred onto grassy carbon substrates by micro-sampling. The crystalline phases of the reference particles with diameters ranging from 1 
m to 5 m were determined non-destructively by using MRS thanks to the optimization of laser power at the measurement. Isotope ratios were also determined with SIMS after the MRS analysis and were consistent with values in the literature. These results indicate that chemical forms and isotope ratios of individual uranium particles as small as 1 m can be analyzed efficiently by using the proposed method.
