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Journal Articles

Trial synthesis of Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ for high-functional tritium breeders

Hoshino, Tsuyoshi; Oikawa, Fumiaki; Natori, Yuri*; Kato, Kenichi*; Sakka, Tomoko*; Nakamura, Mutsumi*; Tatenuma, Katsuyoshi*

Fusion Engineering and Design, 88(9-10), p.2268 - 2271, 2013/10

 Times Cited Count:1 Percentile:87.03(Nuclear Science & Technology)

Lithium titanate with additional Li (Li$$_{2+x}$$TiO$$_{3+y}$$) and lithium orthosilicate (Li$$_{4}$$SiO$$_{4}$$) is one of the most promising candidates for use in a tritium breeder because of its good chemical and mechanical stabilities. Currently, mixtures of tritium breeder pebble and neutron multiplier (Be or Be$$_{12}$$Ti) pebble are being considered for use in increasing the tritium breeding ratio in a breeding blanket. However, lithium and beryllium are gradually reacted under practical operating conditions, and therefore a high-functional tritium breeder such as lithium beryllium oxide (Li$$_{2}$$Be$$_{2}$$O$$_{3}$$) needs to be developed to compensate for this reactive characteristic under high temperature use. In this study, methods of synthesizing Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ have been extensively investigated by means of solid-phase reaction. The solid-phase reaction of LiOH(H$$_{2}$$O) and BeO is a suitable synthesis method for lithium beryllium oxide (Li$$_{2}$$Be$$_{2}$$O$$_{3}$$). It is expected that single-phase Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ will be stable under the mixture conditions of a tritium breeder and neutron multiplier in the blanket region at high temperatures.

Journal Articles

Development of advanced tritium breeding material with added lithium for ITER-TBM

Hoshino, Tsuyoshi; Kato, Kenichi*; Natori, Yuri*; Oikawa, Fumiaki; Nakano, Natsuko*; Nakamura, Mutsumi*; Sasaki, Kazuya*; Suzuki, Akihiro*; Terai, Takayuki*; Tatenuma, Katsuyoshi*

Journal of Nuclear Materials, 417(1-3), p.684 - 687, 2011/10

 Times Cited Count:37 Percentile:4.92(Materials Science, Multidisciplinary)

Lithium titanate (Li$$_{2}$$TiO$$_{3}$$) is one of the most promising candidates among tritium breeding materials because of its good tritium release. Addition of H$$_{2}$$ to inert sweep gas has been proposed for enhancing the tritium release from tritium breeding materials. However, the mass of Li$$_{2}$$TiO$$_{3}$$ was decreased with time in the hydrogen atmosphere. It is assumed that the mass decrease indicates the loss of the oxygen contained in the sample caused by the change from Ti $$^{4+}$$ to Ti $$^{3+}$$, and that the partial pressures of Li-containing species were increased in the hydrogen atmosphere. In order to decrease the mass-change at high temperature, advanced tritium breeding material with added Li should be developed to improve the physical and chemical stability in hydrogen atmosphere. In the case of the Li$$_{2+x}$$TiO$$_{3+y}$$ samples used by the present study, LiOHH$$_{2}$$O and H$$_{2}$$TiO$$_{3}$$ were proportionally mixed with the molar ratio Li/Ti of either 2.0 and 2.2. These samples are designated as L20 (Li/Ti = 2.0) and L22 (Li/Ti = 2.2), respectively. The results of XRD measurement showed that the phases in advanced tritium breeding material were as follows. L22 existed as non-stoichiometric compound Li$$_{2+x}$$TiO$$_{3+y}$$.

Journal Articles

New synthesis method of advanced lithium titanate with Li$$_{4}$$TiO$$_{4}$$ additives for ITER-TBM

Hoshino, Tsuyoshi; Kato, Kenichi*; Natori, Yuri*; Nakamura, Mutsumi*; Sasaki, Kazuya*; Hayashi, Kimio; Terai, Takayuki*; Tatenuma, Katsuyoshi*

Fusion Engineering and Design, 84(2-6), p.956 - 959, 2009/06

 Times Cited Count:38 Percentile:6.09(Nuclear Science & Technology)

Li$$_{2}$$TiO$$_{3}$$ is one of the most promising candidates among the proposed solid breeder materials for fusion reactors. Addition of H$$_{2}$$ to inert sweep gas has been proposed for enhancing the release of bred tritium from breeder material. However, the mass of Li$$_{2}$$TiO$$_{3}$$ was found to decrease with time in the hydrogen atmosphere. This mass change indicates that the oxygen content of the sample decreased, suggesting the change from Ti$$^{4+}$$ to Ti$$^{3+}$$. In order to control the mass change at the time of high temperature use, the development of lithium titanate which has Li$$_{4}$$TiO$$_{4}$$ additive is expected to be effective.

Oral presentation

Development of advanced solid breeder material with added lithium for ITER-TBM

Kato, Kenichi*; Hoshino, Tsuyoshi; Natori, Yuri*; Nakamura, Mutsumi*; Sasaki, Kazuya*; Suzuki, Akihiro*; Terai, Takayuki*; Tatenuma, Katsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

Synthetic test of Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ for high-functional tritium breeder

Hoshino, Tsuyoshi; Natori, Yuri*; Sakka, Tomoko*; Kato, Kenichi*; Oikawa, Fumiaki; Nakamura, Mutsumi*; Tatenuma, Katsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

Synthetic test of Li$$_{2}$$O-BeO system ceramics for advanced tritium breeder

Suzuki, Tatsuya; Hoshino, Tsuyoshi; Natori, Yuri*; Suzuki, Jun*

no journal, , 

Mixtures of tritium breeder (lithium) and neutron multiplier (beryllium) are being considered for use in increasing the tritium breeding ratio in breeding blankets. However, lithium and beryllium react under normal operating conditions, and therefore, a high-functional tritium breeder such as lithium beryllium oxide (Li$$_{2}$$Be$$_{2}$$O$$_{3}$$) needs to be developed to compensate for this reaction under high-temperatures. In this study, we investigated methods of synthesizing Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ by means of solid-state reaction. We measured the weight changes of the starting powders by TG-DTA, and analyzed the chemical composition and crystal structure of the samples by ICP-AES and XRD, respectively.

Oral presentation

Study on development of additive-free dry granulation technology and evaluation of granulation characteristics

Ishii, Katsunori; Segawa, Tomomi; Kawaguchi, Koichi; Nishina, Masahiro; Makino, Takayoshi; Natori, Yuri*

no journal, , 

JAEA is developing simplified a plutonium and uranium mixed oxide (MOX) pellet fabrication process. In this process, agitation granulator improves flowability of MOX powder with water as binder. This granulation method has issues, including low production capacity due to criticality control for wet nuclear material. A new simple additive-free dry granulation method was proposed recently to produce tritium breeding Li$$_{2}$$O spheres for nuclear fusion reactor. In this research, results of experiments to investigate the applicability of the new granulation method to MOX powder is reported.

Oral presentation

Granulation characteristics confirmation test of additive-free dry granulation technology for fast reactor fuel fabrication

Segawa, Tomomi; Kawaguchi, Koichi; Ishii, Katsunori; Nishina, Masahiro; Makino, Takayoshi; Natori, Yuri*; Ikemoto, Norihiro*; Yonehara, Kazuo*; Tatenuma, Katsuyoshi*

no journal, , 

Japan Atomic Energy Agency has researched and developed a simplified MOX pellet fabrication process. the flowability of MOX powder is improved by a tumbling granulation method using water as a binder. However, in this granulation method, improvement of the production capacity under criticality control for wet nuclear material is an issue. In recent years, an additive-free dry granulation technology has proposed as a novel granulation method for producing tritium breeding Li$$_{2}$$O spheres for nuclear fusion reactor. In this study, to confirm the applicability of this method to the MOX fuel fabrication process, CeO$$_{2}$$ powder was used as a simulated material of MOX powder as a basic test for mechanization, and the influence of mechanical external force on granulation was confirmed and evaluated. As a result of the test, good granulation property was obtained by applying a mechanical external force of vertical vibration, and it was possible to obtain the prospect of mechanization of the dry granulation process.

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