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Journal Articles

Development of density control technologies for MOX pellet using dry recycled powders

Nishina, Masahiro; Takeuchi, Kentaro; Murakami, Shinichi

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 8 Pages, 2022/04

no abstracts in English

Journal Articles

Optimization of mechanical properties in aluminum alloys $$via$$ hydrogen partitioning control

Toda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujiwara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.

Tetsu To Hagane, 105(2), p.240 - 253, 2019/02

 Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)

no abstracts in English

JAEA Reports

Backfilling test in drilling pits as part of Groundwater REcovery Experiment in Tunnel (GREET) Project

Takayasu, Kentaro; Onuki, Kenji*; Kawamoto, Koji*; Takayama, Yusuke; Mikake, Shinichiro; Sato, Toshinori; Onoe, Hironori; Takeuchi, Ryuji

JAEA-Technology 2017-011, 61 Pages, 2017/06

JAEA-Technology-2017-011.pdf:9.15MB

The Groundwater REcovery Experiment in Tunnel (GREET) was put into effect as development of drift backfilling technologies. This test was conducted by making the Closure Test Drift (CTD) recovered with water after carrying out a plug around 40m distance from northern edge face of horizontal tunnel of depth 500m, for the purpose of investigation of recovering process of rock mass and groundwater under the influence of excavation of tunnel. This report presents the efforts of backfilling investigation using bentonite composite soil and execution of backfilling into borehole pits excavated in the CTD which were carried out in fiscal 2014 as a part of GREET, and succeeding observation results inside pits from September 2014 to March 2016.

Journal Articles

SPECT imaging of mice with $$^{99m}$$Tc-radiopharmaceuticals obtained from $$^{99}$$Mo produced by $$^{100}$$Mo(n,2n)$$^{99}$$Mo and fission of $$^{235}$$U

Hashimoto, Kazuyuki; Nagai, Yasuki; Kawabata, Masako; Sato, Nozomi*; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji*; Ota, Masayuki; Konno, Chikara; Ochiai, Kentaro; et al.

Journal of the Physical Society of Japan, 84(4), p.043202_1 - 043202_4, 2015/04

 Times Cited Count:7 Percentile:48.86(Physics, Multidisciplinary)

Journal Articles

Development of science-based fuel technologies for Japan's Sodium-Cooled Fast Reactors

Kato, Masato; Hiroka, Shun; Ikusawa, Yoshihisa; Takeuchi, Kentaro; Akashi, Masatoshi; Maeda, Koji; Watanabe, Masashi; Komeno, Akira; Morimoto, Kyoichi

Proceedings of 19th Pacific Basin Nuclear Conference (PBNC 2014) (USB Flash Drive), 12 Pages, 2014/08

Uranium and plutonium mixed oxide (MOX) fuel has been developed for Japan sodium-cooled fast reactors. Science based fuel technologies have been developed to analyse behaviours of MOX pellets in the sintering process and irradiation conditions. The technologies can provide appropriate sintering conditions, irradiation behaviour analysis results and so on using mechanistic models which are derived based on theoretical equations to represent various properties.

Journal Articles

Single crystal growth and various electronic states in Yb-based compounds

Hirose, Yusuke*; Yoshiuchi, Shingo*; Nishimura, Naoto*; Sakaguchi, Junya*; Enoki, Kentaro*; Iwakawa, Ken*; Miura, Yasunao*; Sugiyama, Kiyohiro*; Onuki, Yoshichika; Settai, Rikio*; et al.

Journal of the Korean Physical Society, 62(12), p.1858 - 1861, 2013/06

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Fast and gas-cooled reactor fuels

Takeuchi, Kentaro

Tekisuto "Kakunenryo Saikuru" (Internet), 4 Pages, 2013/02

no abstracts in English

Journal Articles

Measurement of oxygen potential of (U$$_{0.8}$$Pu$$_{0.2}$$)O$$_{2pm x}$$ at 1773 and 1873 K, and its analysis based on point defect chemistry

Kato, Masato; Nakamichi, Shinya; Takeuchi, Kentaro; Sunaoshi, Takeo*

CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 35(4), p.623 - 626, 2011/12

 Times Cited Count:9 Percentile:50.01(Thermodynamics)

Uranium and plutonium mixed oxide (MOX) has been used as fuels of fast reactors. The MOX having fluorite structure is an oxygen nonstoichiometric compound which is stable in hyper- and hypo-stoichiometric composition range. The stoichiometry of MOX significantly affects their properties. So, it is essential to know the relation between stoichiometry and oxygen potential to develop MOX fuels. In this work, the oxygen potentials of (U$$_{0.8}$$Pu$$_{0.2}$$)O$$_{2pm x}$$ were measured at high temperatures of 1773, and 1873K. The measurements were carried out by gas equilibrium method using thermo-gravimetry. Th The oxygen partial pressure was adjusted by controlling the ratio of H$$_{2}$$/H$$_{2}$$O in the flowing gas atmosphere, and the oxygen potential was determined. The oxygen potentials were determined as functions of O/M ratio, and temperature. The data at stoichiometric composition were estimated to be -311kJ/mol and -299kJ/mol at 1773K, and 1873K based on point defect model.

Journal Articles

Development of pressing machine with a die wall lubrication system for the simplified MOX pellet fabrication method in the FaCT project

Sudo, Katsuo; Takano, Tatsuo; Takeuchi, Kentaro; Kihara, Yoshiyuki; Kato, Masato

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Japan Atomic Energy Agency has been contracted to advance the Fast Reactor Cycle Technology Development project. As one part of the project, a simplified MOX pellet fabrication method has been developed for fast reactor fuels. In previous reports, feasibility of a simplified MOX pellet fabrication method was confirmed through hot and cold laboratory-scale experiments. The die wall lubrication pressing technology was one of the important technologies included in the development of the simplified MOX pellet fabrication method. In the work described here, a pressing machine with a die wall lubrication system was developed, and MOX pellet fabrication experiments were carried out on the kilogram MOX scale.

Journal Articles

Development of oxygen-to-metal ratio of MOX pellet adjustment technology for the simplified MOX pellet fabrication method in the FaCT project

Takano, Tatsuo; Sudo, Katsuo; Takeuchi, Kentaro; Kihara, Yoshiyuki; Kato, Masato

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 7 Pages, 2011/12

Development of high burn-up fuels is essential to improve economy of the fast reactor fuel cycle. Increase of fuel burn-up is known to cause fuel-cladding chemical interaction (FCCI) and it mainly determines a lifetime of fuel pin. In order to extend a lifetime of fuel pin by mitigating FCCI, development of low oxygen-to-metal (O/M) MOX fuel has been carried out in plutonium fuel development center of JAEA. MOX fuel needs adjustment of the O/M ratio to less than 1.97 for high burn-up of 150 GWd/t. Therefore, O/M adjustment technology is one of the main subjects in development of a simplified MOX pellet fabrication method which has been advanced in the FaCT (Fast reactor Cycle Technology development) project. In previous work, changes in O/M ratio of MOX pellet during heat treatment were calculated from measurement results of oxygen potentials. On the basis of above calculation, heating tests were carried out to prepare low O/M ratio MOX pellets on a laboratory scale. The O/M ratios obtained in the heating tests were well consistent with calculation results. In the present study, a kilogram MOX scale furnace to adjust O/M ratio of MOX pellets for targeted value has been developed as next step.

Journal Articles

Oxide fuel fabrication technology development of the FaCT project, 3; Analysis of sintering behavior for MOX pellet production

Hiroka, Shun; Kato, Masato; Takeuchi, Kentaro; Takano, Tatsuo

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 6 Pages, 2011/12

In this work, the shrinkage behavior and O/M change of MOX pellet during sintering process were investigated with dilatometer and thermo-gravimeter, and equations to analyze the sintering behavior were derived. The derived equations represented the change of density and O/M ratio of MOX pellet during heat treatment as functions of heat treatment conditions such as heating rate, holding temperature and $$P$$$$_{rm H2}$$/$$P$$$$_{rm H2O}$$ ratio in an atmosphere. They contribute the development of advanced pellet production process and would accurately control density and O/M ratio of MOX pellets.

Journal Articles

Successful labeling of $$^{rm 99m}$$Tc-MDP using $$^{rm 99m}$$Tc separated from $$^{99}$$Mo produced by $$^{100}$$Mo($textit{n}$,2$textit{n}$)$$^{99}$$Mo

Nagai, Yasuki; Hatsukawa, Yuichi; Kin, Tadahiro; Hashimoto, Kazuyuki; Motoishi, Shoji; Konno, Chikara; Ochiai, Kentaro; Takakura, Kosuke; Sato, Yuichi*; Kawauchi, Yukimasa*; et al.

Journal of the Physical Society of Japan, 80(8), p.083201_1 - 083201_4, 2011/08

 Times Cited Count:13 Percentile:63.99(Physics, Multidisciplinary)

We have for the first time succeeded to separate $$^{rm 99m}$$Tc from a Mo oxide sample irradiated by accelerator neutrons, and to formulate $$^{rm 99m}$$Tc-methylene diphosphonate ($$^{rm 99m}$$Tc-MDP). $$^{99}$$Mo, the mother nuclide of $$^{rm 99m}$$Tc, was produced by the $$^{100}$$Mo($textit{n}$,2$textit{n}$)$$^{99}$$Mo reaction using about 14 MeV neutrons provided at the Fusion Neutronics Source of Japan Atomic Energy Agency. The $$^{rm 99m}$$Tc was separated from $$^{99}$$Mo by the sublimation method, and its radionuclide purity was confirmed to be higher than 99.99%. The labeling efficiency of $$^{rm 99m}$$Tc-MDP was shown to be higher than 99%. These values exceed the United States Pharmacopeia requirements for a fission product, $$^{99}$$Mo. Consequently, a $$^{rm 99m}$$Tc radiopharmaceutical preparation formed by using the mentioned $$^{99}$$Mo can be a promising substitute for the fission product $$^{99}$$Mo. A longstanding problem to ensure a reliable and constant supply of $$^{99}$$Mo in Japan can be partially mitigated.

Journal Articles

Influence of O/M ratio on sintering behavior of (U$$_{0.8}$$,Pu$$_{0.2}$$)O$$_{2pm x}$$

Takeuchi, Kentaro; Kato, Masato; Sunaoshi, Takeo*

Journal of Nuclear Materials, 414(2), p.156 - 160, 2011/07

 Times Cited Count:7 Percentile:52.06(Materials Science, Multidisciplinary)

The sintering behavior of MOX pellets was investigated by thermal gravimetry and thermal dilatometry. The starting material was prepared by the microwave direct heating de-nitration method, in which the Pu/(Pu+U) ratio was controlled to 20% in the nitrate solution. The powder was pressed into sample pellets by the die wall lubrication method. The two kind of test, the constant heating rate test and the isochronal heating test, were carried out in various sintering atmospheres of $$P$$$$_{H_2}$$/$$P$$$$_{H_2O}$$ ratio. The results of the constant heating rate test showed that the shrinkage rate and O/M ratio increased with decreasing the $$P$$$$_{H_2}$$/$$P$$$$_{H_2O}$$ ratio. The isochronal heating test was carried out in the O/M range of 1.98 - 2.0005, and the densification behavior of the pellets was analyzed by use of the equation; y = ($$Delta$$$$L$$/$$L$$$$_{0}$$) = $$K$$($$T$$)$$^{n}$$ $$t$$$$^{n}$$. The result showed that the sintering mechanisms varied with the O/M ratio and temperature.

Journal Articles

Oxygen potential of (U$$_{0.88}$$Pu$$_{0.12}$$)O$$_{2pm x}$$ and (U$$_{0.7}$$Pu$$_{0.3}$$)O$$_{2pm x}$$ at high temperatures of 1673-1873 K

Kato, Masato; Takeuchi, Kentaro; Uchida, Teppei; Sunaoshi, Takeo*; Konashi, Kenji*

Journal of Nuclear Materials, 414(2), p.120 - 125, 2011/07

 Times Cited Count:16 Percentile:78.68(Materials Science, Multidisciplinary)

Many studies on oxygen potentials have been reported, but their data were scattered and the data at high temperatures are limited. In this work, the oxygen potential of (U$$_{0.88}$$Pu$$_{0.12}$$)O$$_{2pm x}$$ and (U$$_{0.7}$$Pu$$_{0.3}$$)O$$_{2pm x}$$ was measured at high temperatures of 1673-1873 K using gas equilibrium method using thermo-gravimetry. The influence of Pu addition on the oxygen potential of MOX was discussed. The oxygen potential and the O/M ratio were decided by in-situ analysis. The oxygen partial pressure was adjusted by controlling the ratio of $$P$$$$_{H_{2}}$$/$$P$$$$_{H_{2}}$$O in the flowing gas atmosphere, and the oxygen potential was determined. The oxygen potentials measured by the point defect model. The deviation x varied with the relation of in the near stoichiometric composition region. The oxygen potential increased with increasing Pu content. The values of stoichiometric MOX containing 12% and 30%Pu were determined to be -334 kJ/mol and -296 kJ/mol, respectively, at 1773 K.

JAEA Reports

Characteristics of pore formers in low density MOX pellet fabrication

Mizuno, Mineo; Haga, Tetsuya; Sudo, Katsuo; Takeuchi, Kentaro; Okita, Takatoshi; Kihara, Yoshiyuki

JAEA-Technology 2011-009, 100 Pages, 2011/06

JAEA-Technology-2011-009.pdf:32.59MB

Crystalline cellulose granulated to sizes from 70 to 100 micron was previously used as pore former (PF) to fabricate low density MOX pellets for MONJU. When sale of Avicel was discontinued, it became necessary to find a substitute PF. Then, small scale fabrication tests of MOX pellets with candidate PFs were conducted. Three candidate PFs, cellulose beads, CEOLUS and CELPHERE, were examined in the tests. The results are summarized below. (1) The CELPHERE gave MOX pellets with almost same density depression performance as pellets using Avicel, and standards deviation of the sintered densities of pellets was the smallest. (2) MOX pellets with CELPHERE had lower incidence of observable defects. (3) MOX pellets with CELPHERE had almost the same O/M as pellets with Avicel. (4) MOX pellets with CELPHERE had lower incidence of micro cracks. (5) The densification amount of pellets with CELPHERE was almost the same as that of pellets with Avicel. It was concluded CELPHERE was a suitable substitute for Avicel.

Journal Articles

Effects of H$$_{2}$$/H$$_{2}$$O ratio in the sintering atmosphere on the sintering behavior of MOX pellets

Takeuchi, Kentaro; Kato, Masato; Sunaoshi, Takeo*

Proceedings of 2010 International Congress on Advances in Nuclear Power Plants (ICAPP '10) (CD-ROM), p.1866 - 1873, 2010/06

The effect of the O/M ratio on the sintering behavior of MOX pellets was evaluated from the measurement results of O/M ratio and shrinkage ratio of pellets during the sintering process. Change of O/M ratio was caused by approaching the equilibrium condition which was decided from oxygen potential depending on the H$$_{2}$$/H$$_{2}$$O ratio in the sintering atmosphere. The lower the H$$_{2}$$/H$$_{2}$$O ratio, the more shrinkage of pellets proceeded at lower temperatures and higher O/M values. The curves of shrinkage rate were observed to have two peaks at 1000 to 1300$$^{circ}$$C and 1400 to 1600$$^{circ}$$C. The shrinkage in the lower temperature range increased with decreasing the H$$_{2}$$/H$$_{2}$$O ratio. These results suggested that different mechanisms dominate the sintering behavior at each temperature range. It was confirmed that the sintering behavior of MOX pellet depends on H$$_{2}$$/H$$_{2}$$O ratio and changes significantly with O/M ratio.

Journal Articles

Phase separation behaviour of (U$$_{0.7}$$Pu$$_{0.3}$$)O$$_{2-x}$$ (1.92$$<$$x$$<$$2.00) based fuels containing actinides and/or lanthanides

Komeno, Akira; Kato, Masato; Uno, Hiroki*; Takeuchi, Kentaro; Morimoto, Kyoichi; Kashimura, Motoaki

IOP Conference Series; Materials Science and Engineering, 9, p.012016_1 - 012016_7, 2010/05

 Times Cited Count:8 Percentile:94.52

It is expected that the important data for design of fast reactor fuel can be provided by evaluating the relationship between fuel composition and phase separation with reported and new measurement data. According to evaluation with reported data and new measured data, a relationship between fuel composition and phase separation temperature of MOX fuel was indicated. Higher minor actinides-containing MOX had a lower phase separation temperature at O/M ratio region from 1.92 to 1.96.

Journal Articles

Feasibilyty study on a simplified MOX pellet fabrication process, the short process, for fast breeder reactor fuel

Asakura, Koichi; Takeuchi, Kentaro; Makino, Takayoshi; Kato, Yoshiyuki

Nuclear Technology, 167(3), p.348 - 361, 2009/09

 Times Cited Count:4 Percentile:32.3(Nuclear Science & Technology)

Technological feasibility of a simplified MOX pellet fabrication process, the short process, was studied. About 300 g MH-MOX powder with adjusted plutonium content to 30% could be successfully processed by a tumbling-granulator for subsequent pelletizing and sintering processes. The granulated 30%PuO$$_{2}$$-MOX powder could be pressed into green annular pellets directly and smoothly when using a die wall lubrication method. The pellet tensile strengths were compared for a granulated molybdenum powder and they were higher for pellets obtained when using the die wall lubrication method than when using the conventional powder mixing method. The amount of additives in the green pellets could be controlled at 0.06wt% in this process. It is therefore, possible to carry out de-waxing and sintering of green pellets in the same furnace. By controlling the average particle sizes of granulated 30%PuO$$_{2}$$-MOX powders, pellets with more than 95% theoretical density could be obtained after 1700 $$^{circ}$$C for 2 h. As a result, it can be concluded that the short process is technoligically feasible to fabricate MOX annular pellets.

Journal Articles

Development of an advanced fabrication process for fast reactor MOX fuel pellets

Kato, Masato; Segawa, Tomomi; Takeuchi, Kentaro; Kashimura, Motoaki; Kihara, Yoshiyuki

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.2051 - 2058, 2009/09

In the Fast Reactor Cycle technology Development (FaCT) project conducted by Japan Atomic Energy Agency, minor actinide-containing MOX (MA-MOX) fuel has been developed. The fuel is a homogeneous MOX fuel which contains a maximum of 5% MA such as Am and Np. The oxygen-to-metal (O/M) ratio of the fuel is adjusted to less than 1.97 to control fuel and cladding chemical interaction in a high burn-up of 150 GWd/t. In this paper, the thermal properties of raw powder and sintering behavior of oxidized powder were investigated. In addition the O/M ratio adjustment procedure was established.

Journal Articles

Effective thermal conductivity of MOX raw powder

Takeuchi, Kentaro; Kato, Masato; Sunaoshi, Takeo*; Aono, Shigenori; Kashimura, Motoaki

Journal of Nuclear Materials, 385(1), p.103 - 107, 2009/03

 Times Cited Count:3 Percentile:25.68(Materials Science, Multidisciplinary)

The effective thermal conductivities were evaluated by measuring radial temperature distribution in MH-MOX powder. The effective thermal conductivities were very small and they changed significantly with O/M, bulk density and atmosphere gas. The results in this work were analyzed by the model of Hamilton and Crosser and the new model for the effective thermal conductivity for MH-MOX powder was derived as a function of powder properties, thermal conductivity of atmosphere gas and temperature.

53 (Records 1-20 displayed on this page)