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Journal Articles

Wet separation between palladium(II) and molybdenum(IV) ions by using laser-induced particle formation; Enhancement of recovery efficiency of palladium by laser condition

Saeki, Morihisa; Taguchi, Tomitsugu; Nakashima, Nobuaki*; Oba, Hironori

Journal of Photochemistry and Photobiology A; Chemistry, 299, p.189 - 193, 2015/02

 Times Cited Count:7 Percentile:21.94(Chemistry, Physical)

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

Journal Articles

A Simple radioactivity determination technique by alpha-ray spectrometry for homogenous thick sample

Kameo, Yutaka; Fujiwara, Asako; Watanabe, Koichi; Kono, Nobuaki; Nakashima, Mikio

Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(3), p.187 - 193, 2005/09

no abstracts in English

JAEA Reports

A Study of existing experimental data and validation process for evaluated high energy nuclear data; Report of task force on integral test for JENDEL high energy file in japanese nuclear data committee

Oyama, Yukio; *; Watanabe, Yukinobu*; Kawano, Toshihiko*; Numajiri, M.*; Ueki, Kotaro*; *; Yamano, Naoki*; Kosako, Kazuaki*; *; et al.

JAERI-Review 98-020, 130 Pages, 1998/11

JAERI-Review-98-020.pdf:6.4MB

no abstracts in English

Journal Articles

None

Izawa, Yasukazu*; *; Suto, O.; Wada, Yukio; Nakashima, Nobuaki*

Reza Kenkyu, 26(1), p.112 - 119, 1998/01

None

Oral presentation

Coexistence effect of molybdenum ion in the laser-induced particle formation of palladium

Saeki, Morihisa; Taguchi, Tomitsugu; Matsumura, Daiju; Nakashima, Nobuaki*; Oba, Hironori

no journal, , 

no abstracts in English

Oral presentation

Metal nano-particle formation by femtosecond laser filamentation

Nakashima, Nobuaki*; Yamanaka, Kenichi*; Yatsuhashi, Tomoyuki*; Taniguchi, Seiji*; Saeki, Morihisa; Oba, Hironori

no journal, , 

no abstracts in English

Oral presentation

Coexistence effect of molybdenum ion in the laser-induced particle formation of palladium

Saeki, Morihisa; Taguchi, Tomitsugu; Matsumura, Daiju; Nakashima, Nobuaki*; Oba, Hironori

no journal, , 

no abstracts in English

Oral presentation

XAFS study on effect of molybdenum addition on photo-induced particle formation of palladium

Saeki, Morihisa; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu; Tsuji, Takuya; Kusano, Shogo*; Miyazaki, Tatsuya*; Takao, Koichiro*; Oba, Hironori; Nakashima, Nobuaki*

no journal, , 

Recently, we found that photo-induced particle formation of Pd$$^{2+}$$ was promoted by coexistence of molybdenum anion in aqueous solution. In this study, we performed in-situ time-resolved XAFS measurement in the photoreduction of Pd$$^{2+}$$ in presence of various concentration of molybdenum anion. The effect of molybdenum addition on photo-induced particle formation of Pd will be discussed based on the relationship between the photoreduction rate of Pd$$^{2+}$$ and the concentration of molybdenum anion.

Oral presentation

XAFS study on effect of molybdenum addition on photo-induced particle formation of palladium

Saeki, Morihisa; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu; Tsuji, Takuya; Kusano, Shogo*; Miyazaki, Tatsuya*; Takao, Koichiro*; Oba, Hironori; Nakashima, Nobuaki*

no journal, , 

no abstracts in English

Oral presentation

Development of separation for platinum-group metal using laser-induced photoreduction; Application to radioactive waste disposal

Saeki, Morihisa*; Oba, Hironori*; Taguchi, Tomitsugu*; Yokoyama, Jun*; Asai, Shiho; Yomogida, Takumi; Hanzawa, Yukiko; Nakashima, Nobuaki*

no journal, , 

We are developing separation of platinum-group metals from a solution of high-level radioactive waste by laser-induced particle formation. In this report, we will show method and proof-of-principle experiments of the separation using the laser-induced particle formation.

Oral presentation

Concept of laser-assisted separation and recovery for f-electron elements

Yokoyama, Keiichi; Nakashima, Nobuaki*; Yaita, Tsuyoshi

no journal, , 

We propose a new concept for separating f-electron elements like lanthanides or actinides. These elements have similar chemical property because only the inner shell electronic configuration is different from each other. Therefore, it is considered that chemical techniques alone is hard to complete precise mutual separation between these elements. Meanwhile, the f-f transitions exhibit drastic difference for each element in their photo absorption spectra owing to the inner shell character. There is a possibility to realize precise mutual separation by applying these f-f transitions to the separation processes. In the conference, we introduce and discuss our target and a technical feature in our study plan.

Oral presentation

Laser chemistry for Eu recovery

Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Sakota, Kenji*; Iwakura, Izumi*

no journal, , 

Studies on photo-reduction of trivalent europium, Eu(III), is revisited by nanosecond lasers at various wavelengths with a Ti:Sapphire, excimer, and dye lasers. We measured the quantum yields, wavelength dependence, and power dependence. As a result, we found that the photo-reduction is induced by a two-photon absorption with a relatively high efficiency as to be observed directly with eyes. Also, the quantum yield of one-photon reduction at 308 nm was determined to be 0.6. These results indicate that highly efficient and selective separation techniques are possible for f-electron elements using multi-photon absorption process induced by laser light.

Oral presentation

Reduction of Eu$$^{3+}$$ by multiphoton excitation in alcohol solutions

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*

no journal, , 

The photoredox reactions of lanthanides as a photochemical separative technique proposed in the 1970s are expected to be applied for recovery and recycling of rare metals and nuclear fuel reprocessing. In this study, Eu$$^{3+}$$ ions in methanol and ethanol solutions were reduced to Eu$$^{2+}$$ ions upon irradiation with nanosecond laser pulses. Eu$$^{2+}$$ was observed when the laser wavelength was tuned to f-f transition bands at 394 and 465 nm. The formation rate of Eu$$^{2+}$$ was proportional to the square of the incident laser intensity, indicating that the photoreduction is induced by a two-photon process. The efficiency of the photoreduction in ethanol was higher than that in methanol.

Oral presentation

Fluence dependence of multiphoton reduction of Eu(III) via f-f transition

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*

no journal, , 

The photochemical reactions of lanthanide and actinide ions are expected to be utilized for recovery and recycling of rare earths, and nuclear fuel reprocessing. Heading towards research for implementation of photochemical purification, a unified evaluation of the efficiency of multiphoton processes is required. In this study, we have evaluated the fluence dependence of photoreduction of Eu(III) more precisely than before by measuring the beam profile of the excitation laser. The reduction rate of Eu(III)$$rightarrow$$Eu(II) is proportional to the square of the laser fluence, indicating that the photoreduction of Eu(III) is induced by a two-photon process.

Oral presentation

Photooxidation of trivalent americium in nitric acid

Matsuda, Shohei; Yokoyama, Keiichi; Yaita, Tsuyoshi; Kobayashi, Toru; Nakashima, Nobuaki*

no journal, , 

One of the spectroscopic properties for lanthanides and actinides is that they have f-f transitions in the visible region of their spectra. Those absorption appears at specific wavelength and has narrow line width even in the liquid phase owing to shielded f electrons. It has been reported that reduction reactions of Sm$$^{3+}$$, Eu$$^{3+}$$, and Yb$$^{3+}$$ are induced by multiphoton excitation through each f-f transition depending on conditions. This photochemical process may be applicable to mutual separation of f elements. In this study, we tried to optically control the oxidation state of americium. As a result, we found that trivalent americium (Am$$^{3+}$$) in nitric acid solution is oxidized to pentavalent one (AmO$$_{2}$$$$^{+}$$) during nanosecond pulsed-laser irradiation at 503 nm corresponding to the $$^{5}$$L$$_{6}$$ $$leftarrow$$ $$^{7}$$F$$_{0}$$ transition of Am$$^{3+}$$. Identification and quantification of the reactants and products were performed by absorption spectroscopy. Excitation wavelength dependence and fluence dependence of the oxidation suggest that it is initiated by a resonance-enhanced multiphoton process.

Oral presentation

Oxidation of trivalent americium in nitric acid induced by multiphoton excitation via an f-f transition

Matsuda, Shohei; Yokoyama, Keiichi; Yaita, Tsuyoshi; Kobayashi, Toru; Nakashima, Nobuaki*

no journal, , 

We have recently realized the oxidation of trivalent americium (Am$$^{III}$$) in nitric acid by multiphoton excitation via an f-f transition. In this study, an effect of nitrate ion (NO$$_{3}$$$$^{-}$$) on the Am$$^{III}$$ photooxidation have been investigated. Our results of NO$$_{3}$$$$^{-}$$ activity dependence of the Am$$^{III}$$ photooxidation and density functional theory calculation indicate that the complex of Am$$^{III}$$ with NO$$_{3}$$$$^{-}$$, in particular one-nitrate complex, contributes to it.

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