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Journal Articles

Mechanical and thermal properties of Zr-B and Fe-B alloys

Sun, Y.*; Abe, Yuta; Muta, Hiroaki*; Oishi, Yuji*

Journal of Nuclear Science and Technology, 57(8), p.917 - 925, 2020/08

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

Journal Articles

Low temperature heat capacity of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$

Suzuki, Eriko; Nakajima, Kunihisa; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*

Journal of Nuclear Science and Technology, 57(7), p.852 - 857, 2020/07

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

The low temperature heat capacity of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$, which is one of the cesium chemisorbed compounds onto stainless steel during severe accident of the light water nuclear reactor, was experimentally determined for the first time in the temperature range of 1.9 - 302 K. The experimentally determined heat capacity, $$C_{p}$$$$^{o}$$ (298.15K), and the standard entropy, $$S^{o}$$ (298.15K), were 249.4 $$pm$$ 1.1 J K$$^{-1}$$ mol$$^{-1}$$ and 322.1 $$pm$$ 1.3 J K$$^{-1}$$ mol$$^{-1}$$, respectively. The standard Gibbs energy of formation of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ at high temperatures, $$Delta$$$$_{f}$$$$G^{o}$$($$T$$), were reevaluated by using the presently obtained $$S^{o}$$ (298.15K) and the previously reported experimental results of the standard enthalpy of formation, $$Delta$$$$_{f}$$$$H^{o}$$ (298.15K), and the standard enthalpy increments at high temperatures, $$H^{o}$$($$T$$)-$$H^{o}$$ (298.15K).

Journal Articles

Preliminary study on separation of Dy and Nd by multi-step extraction using TDdDGA

Sasaki, Yuji; Ban, Yasutoshi; Morita, Keisuke; Matsumiya, Masahiko*; Ono, Ryoma*; Shiroishi, Hidenobu*

Solvent Extraction Research and Development, Japan, 27(1), p.63 - 67, 2020/00

Mutual separation technique of Dy and Nd in Nd magnet is studied. Dy is more valuable than Nd, then Dy might be isolated and reused. Lanthanide elements can be extracted thoroughly by diglycolamide (DGA) extractants, we use this reagent for the recovery and isolation of Dy. Tetradodecyl-DGA (TDdDGA) has relatively high separation factors(SF) between Dy and Nd (SF=17-18) in HNO$$_{3}$$ extraction system, counter-current extraction using TDdDGA was applied for their mutual separation. From the present study, using the condition, four extraction stages, organic phase: 0.1M TDdDGA in n-dodecane, aqueous phase: 0.3M HNO$$_{3}$$, 92% Dy can be recovered with 0.7% co-extraction of Nd.

Journal Articles

Chemical trapping of Sr vapor species by Zircaloy cladding under a specific chemical condition

Mohamad, A.*; Nakajima, Kunihisa; Suzuki, Eriko; Miwa, Shuhei; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

In the accident of Fukushima Daiichi Nuclear Power Station, formation of a volatile SrCl$$_{2}$$ could have occurred by the sea-water injection into the core. This can cause the release of non-volatile group Sr from the fuel to induce chemical reactions with reactor structural materials, such as stainless steel and Zircaloy (Zry) cladding. Such reactions could cause the changes in distribution of Sr in the reactor. Chemical reactions between Sr species and Zry were therefore investigated experimentally. As the result, it can be said that Sr vapor species were chemically trapped right after the release from fuel. This trapping effect of Sr by Zry-cladding implies a possibility of preferable Sr retention in the oxide phase of debris.

Journal Articles

Synthesis and characterization of CeO$$_{2}$$-based simulated fuel containing CsI

Takamatsu, Yuki*; Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Kurosaki, Ken*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 17(3/4), p.106 - 110, 2018/12

In order to establish the synthesis method of simulated fuel contacting Cesium (Cs) which is required for the evaluation of physical/chemical characteristics in fuel and release behavior of Cs, sintering tests of the cerium dioxide (CeO$$_{2}$$) based simulated fuels containing Cesium iodide (CsI) are performed by using spark plasma sintering (SPS) method. The sintered CeO$$_{2}$$ pellets with homogeneous distribution of several micro meter of CsI spherical precipitates were successfully obtained by optimizing SPS conditions.

Journal Articles

Effect of hydrogenation conditions on the microstructure and mechanical properties of zirconium hydride

Muta, Hiroaki*; Nishikane, Ryoji*; Ando, Yusuke*; Matsunaga, Junji*; Sakamoto, Kan*; Harjo, S.; Kawasaki, Takuro; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

Journal of Nuclear Materials, 500, p.145 - 152, 2018/03

 Times Cited Count:3 Percentile:35.66(Materials Science, Multidisciplinary)

Journal Articles

Solvent extraction of metal ions using a new extractant, biuret(C8)

Sasaki, Yuji; Yoshimitsu, Ryo*; Nishihama, Shohei*; Shimbori, Yuma*; Shiroishi, Hidenobu*

Separation Science and Technology, 52(7), p.1186 - 1192, 2017/03

 Times Cited Count:1 Percentile:90.43(Chemistry, Multidisciplinary)

The new extractant, biuret(C8), is synthesized and tested for the solvent extraction of hard acid metals like actinides and soft acid metals. This compound has the similar central frame to malonamide but with 2-NH introduced into the central frame, then both amidic oxygen and nitrogen atoms may bond with metals. From the present work, not only hard acid metals, but also soft acid metals can be extracted by biuret(C8) from nitric or perchloric acids to n-dodecane. The extractability for biuret(C8) is compared with other representative extractants, malonamide, TODGA and MIDOA. It is clear that the distribution ratio(D) of U and Pu by biuret(C8) is similar to those for malonamide, but with lower values than those for TODGA and MIDOA, and D for soft acid metals and oxonium anions show higher values than those for TODGA and malonamide and lower than those for MIDOA.

Journal Articles

Formation and morphology of UO$$_{2}$$ image crystal

Serizawa, Hiroyuki; Oishi, Yuji*; Kaji, Yoshiyuki; Yamanaka, Shinsuke*

New Research Trends of Fluorite-Based Oxide Materials, p.243 - 262, 2015/01

The image crystal is a shape controllable negative crystal which is sometimes reported by mineralogist. The negative crystals formed in a large single-crystal mass have attracted interest as expensive jewelry because of their mysterious appearance and rarity. Nonetheless, for many scientist, the cavity has been nothing else than a volume defect which occurs in a single crystal by chance. However, the authors found unexpectedly that the image crystal is formed in UO$$_{2}$$ when helium is enclosed in the gas bubble. They also found that the shape of the image crystal changes dramatically with the conditions of helium precipitation, which implies that the shape of the cavity should change depending on the inner pressure. A truncated octahedron-type, an octa-triacontahedron-type and a pentacontahedron-type negative crystal were observed. Recent study clarified that the growth process of the image crystal can be explained by a step free energy model rather than an attachment energy.

Journal Articles

Thermophysical properties of BaUO$$_{4}$$

Tanaka, Kosuke; Tokushima, Kazuyuki*; Kurosaki, Ken*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*

Journal of Nuclear Materials, 443(1-3), p.218 - 221, 2013/11

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Polycrystalline specimens of barium uranate, BaUO$$_{4}$$, were prepared and several properties such as the thermal expansion coefficient, elastic moduli, thermal conductivity, and Debye temperature were evaluated.

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:3 Percentile:63.46(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.

Journal Articles

Generation of radioisotopes with accelerator neutrons by deuterons

Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sonoda, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro*; Tsukada, Kazuaki; et al.

Journal of the Physical Society of Japan, 82(6), p.064201_1 - 064201_7, 2013/06

 Times Cited Count:30 Percentile:15.22(Physics, Multidisciplinary)

Journal Articles

Complementary characterization of radioactivity produced by repetitive laser-driven proton beam using shot-to-shot proton spectral measurement and direct activation measurement

Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.

Japanese Journal of Applied Physics, 51(4), p.048003_1 - 048003_2, 2012/04

 Times Cited Count:2 Percentile:89.05(Physics, Applied)

A proton beam driven by a repetitive high-intensity-laser is utilized to induce a $$^{7}$$Li(p,n)$$^{7}$$Be nuclear reaction. The total activity of $$^{7}$$Be are evaluated by two different methods. The activity obtained measuring the decay $$gamma$$-rays after 1912 shots at 1 Hz is 1.7$$pm$$0.2 Bq. This is in good agreement with 1.6$$pm$$0.3 Bq evaluated from the proton energy distribution measured using a time-of-flight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system.

Journal Articles

Actinide-handling experience for training and education of future expert under J-ACTINET

Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.

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

Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.

Journal Articles

Suppression of time-reversal symmetry breaking superconductivity in Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$ and Pr$$_{1-y}$$La$$_y$$Os$$_4$$Sb$$_{12}$$

Shu, L.*; Higemoto, Wataru; Aoki, Yuji*; Hillier, A. D.*; Oishi, Kazuki*; Ishida, Kenji*; Kadono, Ryosuke*; Koda, Akihiro*; Bernal, O. O.*; MacLaughlin, D. E.*; et al.

Physical Review B, 83(10), p.100504_1 - 100504_4, 2011/03

 Times Cited Count:23 Percentile:26.67(Materials Science, Multidisciplinary)

Zero-field muon spin relaxation experiments have been carried out in the Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$ and Pr$$_{1-y}$$La$$_y$$Os$$_4$$Sb$$_{12}$$ alloy systems to investigate broken time-reversal symmetry (TRS) in the superconducting state, signaled by the onset of a spontaneous static local magnetic field B$$_s$$. In both alloy series B$$_s$$ initially decreases linearly with solute concentration. Ru doping is considerably more efficient than La doping, with a 50% faster initial decrease. The data suggest that broken TRS is suppressed for Ru concentration $$xgeq$$0.6 but persists for essentially all La concentrations. Our data support a crystal-field excitonic cooper pairing mechanism for TRS-breaking superconductivity.

Journal Articles

Laser-driven proton generation with a thin-foil target

Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Ma, J.*; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

NIFS-PROC-85, p.30 - 33, 2011/02

The experiment of proton generation is performed for developing the laser-driven ion source. We observe proton signals in the laser-plasma interaction by using a thin-foil target. To get higher energy protons the size of the preformed plasma is reduced by changing the laser contrast level. In the high-contrast laser pulse case the maximum energy of the protons generated at rear side of the target increases.

Journal Articles

Chemical states of fission products and actinides in irradiated oxide fuels analyzed by thermodynamic calculation and post-irradiation examination

Kurosaki, Ken*; Tanaka, Kosuke; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Uno, Masayoshi*; Yamanaka, Shinsuke*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

It is important to understand the behavior of fission products and actinides under irradiation. In the present study, the chemical states of fission products and actinides in irradiated oxide fuels were evaluated by both thermodynamic equilibrium calculation and post-irradiation examination.

Journal Articles

Proton generation and terahertz radiation from a thin-foil target with a high-intensity laser

Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Ma, J.*; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

Reza Kenkyu, 38(9), p.702 - 705, 2010/09

High-intensity laser and thin-foil interactions produce high-energy particles, hard X-ray, high-order harmonics, and terahertz (THz) radiation. A proton beam driven by a high-intensity laser has received attention as a compact ion source for medical applications. In this study we have tested simultaneous generation of protons and THz radiation from a thin-foil target. We use a Ti:sapphire laser system (J-KAREN) at JAEA. A laser beam is focused by an off-axis parabolic mirror at the thin-foil target. We observed the high-energy proton in the rear side of the target and THz radiation in the reflected direction. Next, high energy protons are observed by reducing the size of preformed plasma.

Journal Articles

Characterization of electron self-injection in laser wake field acceleration due to the parametric resonance

Zhidkov, A.*; Koga, J. K.; Hosokai, Tomonao*; Fujii, Takashi*; Oishi, Yuji*; Nemoto, Koshichi*; Kodama, Ryosuke*

Physics of Plasmas, 17(8), p.083101_1 - 083101_6, 2010/08

 Times Cited Count:11 Percentile:53.41(Physics, Fluids & Plasmas)

Journal Articles

Microscopic study of antiferromagnetic ground state and possible high-field ordered state in CeOs$$_4$$Sb$$_{12}$$ using muon spin rotation and relaxation

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Sato, Kazuhiko*; Aoki, Yuji*; Toda, Shizuka*; Kikuchi, Daisuke*; Sato, Hideyuki*; Baines, C.*

Physical Review B, 82(1), p.014420_1 - 014420_8, 2010/07

 Times Cited Count:7 Percentile:61.79(Materials Science, Multidisciplinary)

An antiferromagnetic (AFM) ground state and a possible high-field ordered state in magnetic fields $$H>1$$ T of a filled-skutterudite compound CeOs$$_4$$Sb$$_{12}$$ were investigated by the muon spin rotation and relaxation method. In a zero applied field, a spontaneous local filed due to the weak AFM ordering was observed below $$sim$$1.6 K. The magnetic volume fraction gradually increases below 1.6 K with decreasing temperature, suggesting that this phase is sensitive to sample quality. The magnitude of the ordered dipole moment in the AFM state was estimated to be in the range from 0.11 to 0.17 $$mu_B$$/Ce at 0.1 K. In a field of 2 T applied along the [001] direction, clear anomalies in the muon Knight shift and line width were observed at $$sim$$ 1.5 K, consistent with the phase transition scenario into the high-field ordered state suggested from specific heat, resistivity, elastic, and NMR anomalies.

Journal Articles

$$mu^+$$ diffusion in cubic $$f$$-electron compounds observed by high transverse field $$mu^+$$SR

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Heffner, R. H.; Aoki, Yuji*; Suzuki, Hiroyuki*; Onimaru, Takahiro*; Tanida, Hiroshi*; Takagi, Shigeru*

Journal of Physics; Conference Series, 225, p.012021_1 - 012021_6, 2010/06

 Times Cited Count:1 Percentile:45.2

The diffusion of positive muon $$mu^+$$ in condensed matter has been investigated for many years by using $$mu^+$$ spin rotation/relaxation ($$mu^+$$SR) technique. The $$mu^+$$SR studies have provided deep insight into quantum diffusion at low temperatures as well as hopping process at high temperatures, which are closely related to hydrogen dynamics in the dilute limit. We here report transverse field (TF) $$mu^+$$SR studies of the $$mu^+$$ diffusion in cubic $$f$$-electron compounds PrPb$$_3$$ and SmAg$$_2$$In. The $$mu^+$$ site splits into two magnetically labeled sites when high TF is applied to single-crystalline specimens along the [001] direction. The $$mu^+$$SR lines show drastic variation according to the $$mu^+$$ motion between the magnetically labeled sites. From detailed analysis of the $$mu^+$$SR lines, we deduced $$mu^+$$ hopping parameters for both compounds.

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