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Journal Articles

Chemical form consideration of released fission products from irradiated fast reactor fuels during overheating

Sato, Isamu; Tanaka, Kosuke; Koyama, Shinichi; Matsushima, Kenichi*; Matsunaga, Junji*; Hirai, Mutsumi*; Endo, Hiroshi*; Haga, Kazuo*

Energy Procedia, 82, p.86 - 91, 2015/07

 Times Cited Count:2 Percentile:17.75(Nuclear Science & Technology)

Experiments simulating overheating conditions of fast reactor severe accidents have been previously carried out with irradiated fuels. For the present study, the chemical forms of the fission products (FPs) included in the irradiated fuels were evaluated by thermochemical equilibrium calculations. At temperatures of 2773 K and 2973 K, the most stable forms of Cs, I, Te, Sb, Pd and Ag are gaseous compounds. Cs and Sb detected in the thermal gradient tube (TGT) in the experiments can take gaseous chemical forms of elemental Cs, CsI, Cs$$_{2}$$MoO$$_{4}$$, CsO and elemental Sb, SbO, SbTe, respectively. By comparing experimental results and the estimations, it is seen CsI thermochemically behaves in a manner that traps it in the TGT, while elemental Cs trends to move as fine particles. The moving behavior of the gaseous FPs will obey not only thermochemical principles, but also those of particle dynamics.

Journal Articles

Formation and growth of image crystals by helium precipitation

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Akabori, Mitsuo; Tsuru, Tomohito; Kaji, Yoshiyuki; Kashibe, Shinji*; Oishi, Yuji*; Yamanaka, Shinsuke*

Crystal Growth & Design, 13(7), p.2815 - 2823, 2013/07

 Times Cited Count:5 Percentile:42.85(Chemistry, Multidisciplinary)

Since the shape of the negative crystal closely relates to the morphology of the crystal habits, the formation and the growth mechanism is important subject in a field of the physical science. Whereas, the negative crystal formed in a large single crystal mass has been arousing interest as an expensive jewelry because of its mysterious appearance and rarity. However, it is difficult to control the shape of this polyhedral cavity embedded in a solid medium arbitrary. Here we report the recent discovery on the growth process of the negative crystal. We found that precipitated helium forms the negative crystal in UO$$_{2}$$; the shape changes drastically with the condition of the helium precipitation. The transformation mechanism was discussed in this article. Our investigation implies that the shape of the negative crystal can be arbitrary controlled by controlling the precipitation condition.

JAEA Reports

Study on helium behavior in oxide fuel, 1; Deformation of microstructure induced by precipitation of helium (Joint research)

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Kashibe, Shinji*; Iwai, Takashi

JAEA-Research 2011-025, 32 Pages, 2011/11

JAEA-Research-2011-025.pdf:10.17MB

This report deals with the precipitation of helium in UO$$_{2}$$ matrix to deform the microstructure. The examination was performed using single and polycrystalline UO$$_{2}$$ sample. The helium-treated samples under 900 atm at 1473 K were reheat-treated at much more high temperature, 1573 K or 1973 K to release the infused helium. The microstructure of the sample was examined by FIB, FE-STEM and FE-TEM. It was confirmed that precipitated helium atoms form a negative crystal in the grain or the matrix of the single crystal. At 1573 K, helium can be released without formation of intergranular tunnel since the surface diffusion coefficient of helium is large. However, some open grain boundaries were observed in the sample heat-treated at 1973 K. This might be related to the activity of helium in the grain boundary region. The structure of the negative crystal was analyzed from the view point of the thermodynamics of the surface growth.

Journal Articles

Fabrication of nanowires by varying energy microbeam lithography using heavy ions at the TIARA

Kamiya, Tomihiro; Takano, Katsuyoshi; Ishii, Yasuyuki; Sato, Takahiro; Oikawa, Masakazu*; Okubo, Takeru; Haga, Junji*; Nishikawa, Hiroyuki*; Furuta, Yusuke*; Uchiya, Naoyuki*; et al.

Nuclear Instruments and Methods in Physics Research B, 267(12-13), p.2317 - 2320, 2009/06

 Times Cited Count:7 Percentile:47.19(Instruments & Instrumentation)

Journal Articles

Development of micromachining technology in ion microbeam system at TIARA, JAEA

Kamiya, Tomihiro; Nishikawa, Hiroyuki*; Sato, Takahiro; Haga, Junji; Oikawa, Masakazu*; Ishii, Yasuyuki; Okubo, Takeru; Uchiya, Naoyuki; Furuta, Yusuke*

Applied Radiation and Isotopes, 67(3), p.488 - 491, 2009/03

 Times Cited Count:4 Percentile:30.6(Chemistry, Inorganic & Nuclear)

Development of a mask-less ion beam lithography technique for fabricating micro- or nano-meter sized structures has been started at the microbeam systems in the ion accelerator facility of JAEA Takasaki (TIARA) in collaboration with Shibaura Institute of Technology. In order to obtain a high precision measure for microbeam size estimation and lens system optimization, or for improvement of spatial resolution down to 100 nm level, we applied this lithography technique itself combined with the electroplating process to make a Ni relief pattern as an optimum resolution standard to be used in secondary electron imaging. In this work, using this standard, the smallest beam size could be obtained. This paper also discuses on the scattering of ions in the materials influenced to the resolution using a Monte Carlo simulation code.

Journal Articles

Ni electroplating on a resist micro-machined by proton beam writing

Uchiya, Naoyuki*; Furuta, Yusuke*; Nishikawa, Hiroyuki*; Watanabe, Toru*; Haga, Junji; Sato, Takahiro; Oikawa, Masakazu; Ishii, Yasuyuki; Kamiya, Tomihiro

Microsystem Technologies, 14(9-11), p.1537 - 1540, 2008/10

 Times Cited Count:17 Percentile:64.39(Engineering, Electrical & Electronic)

Journal Articles

Preliminary study on a compact MeV focused ion nanobeam system

Ishii, Yasuyuki; Okubo, Takeru; Haga, Junji*; Adachi, Shigeto*; Yoshida, Eiji*

Proceedings of the Symposium on Accelerator and Related Technology for Application, Vol.10, p.9 - 10, 2008/06

no abstracts in English

Journal Articles

Improvement of ion microbeam scanning system in JAERI Takasakai; Development of proton beam writing

Sakai, Takuro; Sato, Takahiro; Ishii, Yasuyuki; Oikawa, Masakazu*; Shimada, Hirofumi*; Haga, Junji*

Dai-18-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.73 - 76, 2005/10

no abstracts in English

Oral presentation

Micro-machining of resist on silicon by proton beam writing

Uchiya, Naoyuki*; Harada, Takuya*; Nishikawa, Hiroyuki*; Haga, Junji; Sakai, Takuro; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro

no journal, , 

no abstracts in English

Oral presentation

Micro-machining of resist materials using MeV proton microbeams

Uchiya, Naoyuki*; Harada, Takuya*; Murai, Masato*; Nishikawa, Hiroyuki*; Haga, Junji; Sato, Takahiro; Oikawa, Masakazu*; Sakai, Takuro; Ishii, Yasuyuki; Fukuda, Mitsuhiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Production of 3-D resit structures on silicon plates by a proton beam writing technique

Furuta, Yusuke*; Uchiya, Naoyuki*; Nishikawa, Hiroyuki*; Haga, Junji; Oikawa, Masakazu*; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro

no journal, , 

no abstracts in English

Oral presentation

Development of a focused ion beam technique in MeV range using acceleration-lenses with large demagnification

Ishii, Yasuyuki; Okubo, Takeru; Haga, Junji; Kobayashi, Akira*; Adachi, Shigeto*

no journal, , 

no abstracts in English

Oral presentation

Micro-machining of resists by proton beam writing, 2; Fabrication of 3-D structures using a negative resist

Uchiya, Naoyuki; Furuta, Yusuke*; Nishikawa, Hiroyuki*; Haga, Junji; Sato, Takahiro; Oikawa, Masakazu*; Okubo, Takeru; Ishii, Yasuyuki; Kamiya, Tomihiro; Yamamoto, Shunya

no journal, , 

no abstracts in English

Oral presentation

Three-dimensional elemental analysis by in-air micro-PIXE

Sato, Takahiro; Oikawa, Masakazu*; Haga, Junji

no journal, , 

The image reconstruction technique of X-ray CT was applied to in-air micro-PIXE to measure three-dimensional distribution of the trace elements in a sample. In this study, the polyethylene fiber containing some kinds of metal was used as a sample, and three-dimensional distribution was measured by rotating the sample.

Oral presentation

Design of a high-demagnification acceleration lens system for formation of MeV ion nanobeams

Ishii, Yasuyuki; Okubo, Takeru; Haga, Junji; Kobayashi, Akira*; Adachi, Shigeto*

no journal, , 

no abstracts in English

Oral presentation

Development of a high-brightness multicusp ion source for focused ion beam generation, 1

Tsuji, Toshiyuki*; Kobayashi, Akira*; Yoshida, Eiji*; Ichihara, Chikara*; Adachi, Shigeto*; Ishii, Yasuyuki; Haga, Junji

no journal, , 

no abstracts in English

Oral presentation

In-air micro-PIXE analysis of asbestos and metal elements in asbestos exposed lung

Shimizu, Yasuo*; Dobashi, Kunio*; Kusakabe, Takahiko*; Nagamine, Takeaki*; Oikawa, Masakazu*; Sato, Takahiro; Haga, Junji*; Okubo, Takeru; Ishii, Yasuyuki; Kamiya, Tomihiro; et al.

no journal, , 

no abstracts in English

Oral presentation

Negative crystal fabricated by helium infusion for UO$$_2+x$$

Matsunaga, Junji*; Kashibe, Shinji*; Serizawa, Hiroyuki; Nakajima, Kunihisa; Iwai, Takashi; Haga, Yoshinori; Oishi, Yuji*; Yamanaka, Shinsuke*

no journal, , 

The aim of this study is to clarify the behavior of helium precipitated in UO$$_2$$. The micro-structure of UO$$_2$$ matrix deformed by helium infusion was examined by FE-SEM and FE-TEM. It was deduced that the shape of the negative crystal is determined by the balance between the surface energy of the lattice plane and the inner pressure of helium.

Oral presentation

Helium bubbles in UO$$_{2}$$

Matsunaga, Junji*; Kashibe, Shinji*; Serizawa, Hiroyuki; Nakajima, Kunihisa; Iwai, Takashi; Haga, Yoshinori; Oishi, Yuji*; Yamanaka, Shinsuke*

no journal, , 

Helium generated in MOX fuel increases inner pressure of fuel rod and helium could also form additional bubbles in fuel pellet by the combination of radiation defects and high temperature. Therefore it is important to understand the behavior of helium in oxide fuel for reliable operation of MOX fuels. In the present study, the helium infusion treatments in high temperature and high pressure of helium were performed for both sintered polycrystalline UO$$_{2}$$ fragments and hyperstoichiometric monograin UO$$_{2+x}$$ particles fabricated by the transportation method. It was suggested that the difference in the composition of UO$$_{2}$$ is closely related with the condition of the formation of the negative crystal.

Oral presentation

Relationship between shape of negative crystal in helium infused UO$$_{2}$$ and its inner pressure

Matsunaga, Junji*; Kashibe, Shinji*; Serizawa, Hiroyuki; Nakajima, Kunihisa; Iwai, Takashi; Haga, Yoshinori; Oishi, Yuji*; Yamanaka, Shinsuke*

no journal, , 

In the present study, the helium infusion were conducted at high temperature with highly pressurized helium for both UO$$_{2}$$. Following a high temperature treatment, the negative crystal formed in the sample was examined by FE-SEM. The SEM image was analyzed to measure the area of the surface on the negative crystal which is composed of facetted lattice planes. It was confirmed that the shape of the negative crystal formed in this method is deviated from the equilibrium shape reported previously, which means that the higher inner pressure produced by the helium precipitated in the cavity relate to the shape of the negative crystal.

23 (Records 1-20 displayed on this page)