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Journal Articles

Present status of the tandem accelerator at the JAEA-AMS-TONO; 2015

Fujita, Natsuko; Matsubara, Akihiro*; Watanabe, Takahiro; Kokubu, Yoko; Umeda, Koji*; Ishimaru, Tsuneari; Nishizawa, Akimitsu*; Miyake, Masayasu; Owaki, Yoshio*; Nishio, Tomohiro*; et al.

Dai-29-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.39 - 42, 2017/03

no abstracts in English

Journal Articles

Present status of the JAEA-AMS-TONO; 2015

Fujita, Natsuko; Matsubara, Akihiro; Watanabe, Takahiro; Kokubu, Yoko; Umeda, Koji; Nishizawa, Akimitsu*; Miyake, Masayasu*; Owaki, Yoshio*; Nishio, Tomohiro*; Kato, Motohisa*

Dai-18-Kai AMS Shimpojiumu Hokokushu, p.85 - 90, 2016/12

no abstracts in English

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific programme for fiscal year 2015)

Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Matsubara, Akihiro; Tamura, Hajimu; Yokoyama, Tatsunori; et al.

JAEA-Review 2015-019, 42 Pages, 2015/09

JAEA-Review-2015-019.pdf:4.64MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in JAEA, in fiscal year 2015. The objectives and contents in fiscal year 2015 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Research on geosphere stability for long-term isolation of radioactive waste; Scientific programme for fiscal years 2015-2021

Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Shimada, Akiomi; Matsubara, Akihiro; Tamura, Hajimu; et al.

JAEA-Review 2015-012, 43 Pages, 2015/08

JAEA-Review-2015-012.pdf:1.24MB

The concept of geological disposal of high-level radioactive waste (HLW) in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in tectonically active zone. This report is to outline 7 years plan (fiscal years 2015-2021) of research and development (R&D) for geosphere stability for long-term isolation of the HLW in JAEA. Background of this research is clarified with the necessity and the significance, and the past progress in this report. The objectives, outline, contents and schedule during the next 7 years are described in detail. In addition, the plan framework is structured into the following categories: (1) Development and Systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific programme for fiscal year 2014)

Yasue, Kenichi; Asamori, Koichi; Niwa, Masakazu; Kokubu, Yoko; Kobori, Kazuo; Makuuchi, Ayumu; Matsubara, Akihiro; Shibata, Kenji; Tamura, Hajimu; Tanabe, Hiroaki; et al.

JAEA-Review 2014-033, 43 Pages, 2014/09

JAEA-Review-2014-033.pdf:16.91MB

The concept of geological disposal of HLW in Japan is based on a multi-barrier system which combines a stable geological environment with a robust barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2014. The objectives and contents in fiscal year 2014 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Journal Articles

Quaternary geochronology using accelerator mass spectrometry (AMS); Current status of the AMS system at the Tono Geoscience Center

Matsubara, Akihiro; Kokubu, Yoko; Nishizawa, Akimitsu*; Miyake, Masayasu*; Ishimaru, Tsuneari; Umeda, Koji

Geochronology; Methods and Case Studies, p.3 - 30, 2014/07

Our ongoing efforts have been dedicated to development of a multi-nuclide AMS system for measurement of the rare radionuclides $$^{10}$$Be, $$^{14}$$C, $$^{26}$$Al, and $$^{36}$$Cl. In this article, the current status of the AMS system at the TONO-AMS-JAEA and our activities leading to development of a multi-nuclide AMS are presented.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2012

Yasue, Kenichi; Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Kokubu, Yoko; Sueoka, Shigeru; Makuuchi, Ayumu; Ikuta, Masafumi; Matsubara, Akihiro; Tamura, Hajimu; et al.

JAEA-Research 2013-047, 109 Pages, 2014/03

JAEA-Research-2013-047.pdf:6.81MB

This annual report documents the progress of R&D in the 3rd fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific programme for fiscal year 2013)

Yasue, Kenichi; Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Kokubu, Yoko; Makuuchi, Ayumu; Ikuta, Masafumi; Matsubara, Akihiro; Ishimaru, Tsuneari; Umeda, Koji

JAEA-Review 2013-023, 42 Pages, 2013/10

JAEA-Review-2013-023.pdf:2.82MB

The concept of geological disposal of HLW in Japan is based on a multi-barrier system which combines a stable geological environment with a robust barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2013. The objectives and contents in fiscal year 2013 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Journal Articles

Current status of the AMS facility at the Tono Geoscience Center of the Japan Atomic Energy Agency

Kokubu, Yoko; Nishizawa, Akimitsu*; Suzuki, Mototaka*; Owaki, Yoshio*; Nishio, Tomohiro*; Matsubara, Akihiro; Saito, Tatsuo; Ishimaru, Tsuneari; Umeda, Koji; Hanaki, Tatsumi

Nuclear Instruments and Methods in Physics Research B, 294, p.43 - 45, 2013/01

 Times Cited Count:3 Percentile:29.69(Instruments & Instrumentation)

The Tono Geoscience center of JAEA installed the JAEA-AMS-TONO system at 1997. Since 1998, the system has routinely used for $$^{14}$$C-AMS. Recently, about 800 samples/y have been measured mainly for studies of neotectonics and hydrogeology in relation to research of geosphere stability for long-term Isolation of high-level radioactive waste. Under the common-use facility program, the system has also been used by researchers of universities and other institutes. In addition, $$^{10}$$Be-AMS has been developed for geochronological study. A gas ionisation detector was exchanged. As the detector has a gas absorber cell which has larger volume than the previous one, it is possible to remove $$^{10}$$B efficiently. Test measurement by using several standard samples supplied from University of California, Berkeley was performed. Ratios of $$^{10}$$Be/$$^{9}$$Be were comparable to the certified values, indicating that our system has sufficient ability to be useful to $$^{10}$$Be-AMS.

Journal Articles

Change in the electrical performance of GaAs solar cells with InGaAs quantum dot layers by electron irradiation

Oshima, Takeshi; Sato, Shinichiro; Imaizumi, Mitsuru*; Nakamura, Tetsuya*; Sugaya, Takeyoshi*; Matsubara, Koji*; Niki, Shigeru*

Solar Energy Materials and Solar Cells, 108, p.263 - 268, 2013/01

 Times Cited Count:12 Percentile:51.84(Energy & Fuels)

GaAs solar cells which have a PiN structure with 50 self-organized In$$_{0.4}$$Ga$$_{0.6}$$As Quantum Dot (QD) layers were irradiated with 1 MeV electrons up to 1$$times$$10$$^{16}$$ /cm$$^{2}$$. After irradiation at 1$$times$$10$$^{16}$$/cm$$^{2}$$, the remaining factor of I$$_{rm SC}$$, V$$_{rm OC}$$ and P$$_{rm MAX}$$ for the InGaAs 50 QD solar cell becomes 80, 90 and 55% of the initial values, respectively. On the other hand, those values for non QD GaAs solar cells decrease to 95, 80 and 63% of the initial values, respectively. Since the i-layer for the 50 QD solar cells (1.1 $$mu$$m) is thicker than the non QD solar cells (660 nm), the larger degradation of I$$_{rm SC}$$ for the 50 QD solar cells than the non QD ones can be interpreted in terms that the carrier recombination in the i-layer for the 50 QD solar cells is larger than that for the non QD solar cells. For V$$_{rm OC}$$, the 50 QD solar cells showes better radiation resistance than the non QD solar cells. Furthermore, the annealing behavior of the electrical characteristics for the 50 QD and the non QD solar cells was investigated at RT under AM 0 immediately after the irradiation. As a result, the recovery of the electrical characteristics for both solar cells was observed, and the GaAs solar cells shows relatively larger recovery compared to the 50 QD solar cells. Although the mechanism of this recovery has not yet been clarified, the origin of this recovery is thought not to come from the existence of QDs because the GaAs solar cell without QD layers also shows the recovery.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2011

Asamori, Koichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamada, Kunimi; Kusano, Tomohiro; Makuuchi, Ayumu; Takatori, Ryoichi; Kokubu, Yoko; Matsubara, Akihiro; Ishimaru, Tsuneari; et al.

JAEA-Research 2012-024, 132 Pages, 2012/09

JAEA-Research-2012-024.pdf:15.68MB

This annual report documents the progress of R&D in the 2nd fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planed framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Extraction and separation of uranium from simulated uranium-containing liquid wastes of Ningyo-toge environmental engineering center

Mitamura, Hisayoshi; Naganawa, Hirochika; Nagano, Tetsushi; Yanase, Nobuyuki; Hanzawa, Yukiko; Shimojo, Kojiro; Matsubara, Tatsuo; Mita, Yutaka; Taki, Tomihiro; Murata, Masato

JAEA-Research 2008-113, 27 Pages, 2009/03

JAEA-Research-2008-113.pdf:31.84MB

An effective mass processing equipment using solvent extraction method, named "emulsion flow extractor," is the most promising apparatus for removal and recovery of uranium from liquid waste originated from decontamination of uranium-contaminated fluoride waste in the uranium conversion test facility and of used gas centrifuges in the uranium enrichment facility at Ningyo-toge environmental engineering center. Prior to application of the emulsion flow extractor for actual uranium-containing liquid waste, properties of some phosphorous extractants for extraction and separation of uranium and constituents from simulated liquid wastes were examined through batch tests. These preliminary tests revealed that D2EHPA would be a promising candidate for extractant used for treatment of the actual uranium-containing liquid wastes, and that the extractants with a surfactant like AOT would not be useful.

Journal Articles

Gated multiple-sampling and tracking proportional chamber; New detector system for nuclear astrophysical study with radioactive nuclear beams

Hashimoto, Takashi; Ishiyama, Hironobu*; Ishikawa, Tomoko*; Kawamura, Takashi*; Nakai, Koji*; Watanabe, Yutaka*; Miyatake, Hiroari; Tanaka, Masahiko*; Fuchi, Yoshihide*; Yoshikawa, Nobuharu*; et al.

Nuclear Instruments and Methods in Physics Research A, 556(1), p.339 - 349, 2006/01

 Times Cited Count:31 Percentile:89.78(Instruments & Instrumentation)

A new type of three dimensional tracking and proportional gas counter has been developed. Adopting a gating-grid system, performance of the detector becomes stable under the injection rate of charged particles less than 4$$times$$10$$^4$$ pps. It is a useful detection system for astrophysical experiments using radioactive nuclear beams, since the efficiency is so high as 100 %.

Journal Articles

Higher-order collinear interaction and magnetic excitation in the 5f localized system U$$_{3}$$Pd$$_{20}$$Si$$_{6}$$

Metoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Kaneko, Koji; Araki, Shingo; McEwen, K. A.*; Kogi, Masafumi*; Aso, Naofumi*; Lander, G. H.; Komatsubara, Takemi*; et al.

Journal of Physics; Condensed Matter, 15(28), p.S1957 - S1963, 2003/07

 Times Cited Count:2 Percentile:15.73(Physics, Condensed Matter)

no abstracts in English

Oral presentation

Radiation degradation of the electrical performance of InGaAs quantum dot solar cells and its recovery at room temperature

Oshima, Takeshi; Sato, Shinichiro; Imaizumi, Mitsuru*; Nakamura, Tetsuya*; Sugaya, Takeyoshi*; Matsubara, Koji*; Niki, Shigeru*

no journal, , 

Oral presentation

Radiocarbon measurement of JAEA-AMS-TONO at the Tono geosciences center and its application of investigation for fault

Kokubu, Yoko; Yasue, Kenichi; Niwa, Masakazu; Matsubara, Akihiro; Umeda, Koji; Ishimaru, Tsuneari; Shimada, Koji

no journal, , 

no abstracts in English

Oral presentation

Geoscience studies using by AMS at JAEA-AMS-TONO in the Tono Geoscience Center of the Japan Atomic Energy Agency

Kokubu, Yoko; Matsubara, Akihiro; Hanaki, Tatsumi; Yasue, Kenichi; Umeda, Koji

no journal, , 

The JAEA-AMS-TONO facility was established in 1997 at the Tono Geoscience Center, Japan Atomic Energy Agency (JAEA). Our AMS system is a versatile system based on a 5MV tandem Pelletron type accelerator (National Electrostatic Corporation, US) and has been made available for $$^{14}$$C-, $$^{10}$$Be- and $$^{26}$$Al-AMSs. These multi-nuclide AMSs have been mainly applied to neotectonics and hydrogeology, in support of our research on geosphere stability applicable to the long-term isolation of high-level radioactive waste. Furthermore, the $$^{14}$$C- and $$^{10}$$Be-AMSs are used for geoscience, environmental science and archaeology by researchers of universities and other institutes under the JAEA's common-use facility program. In this presentation, we introduce dating of $$^{14}$$C and $$^{10}$$Be through our AMS to geoscience studies. Moreover we report development of $$^{26}$$Al-AMS.

Oral presentation

Radiation response of fill-factor for GaAs solar cells with InGaAs quantum dot layers

Nakamura, Tetsuya*; Sumita, Taishi*; Imaizumi, Mitsuru*; Sugaya, Takeyoshi*; Matsubara, Koji*; Niki, Shigeru*; Mochizuki, Toru*; Takeda, Akihiro*; Okano, Yoshinobu*; Sato, Shinichiro; et al.

no journal, , 

Radiation effects on GaAs solar cells with InGaAs dot layers were investigated in order to consider the capability of them for space applications. The GaAs solar cells with 50 InGaAs dot layers and also GaAs solar cells with no dot layer were fabricated using a MBE method. They were irradiated with 150 keV-protons at room temperature. As a result, solar cell with dot layers showed higher radiation degradation in short circuit current however, lower degradation in open circuit voltage. Since no significant difference in the degradation of current - voltage characteristics under dark conditions between dot and non-dot solar cells, it is concluded that the degradation of fill fuctor does not come from the degradation of pn diode characteristics but might come from the degradation of minority carrier diffusion length.

Oral presentation

In-situ observation of radiation degradation of GaAs solar cells with InGaAs quantum dot layers

Oshima, Takeshi; Nakamura, Tetsuya*; Sugaya, Takeyoshi*; Sumita, Taishi*; Imaizumi, Mitsuru*; Sato, Shinichiro; Matsubara, Koji*; Niki, Shigeru*; Mochizuki, Toru*; Takeda, Akihiro*; et al.

no journal, , 

Oral presentation

Evaluation of radiation degradation of GaAs solar cells with InGaAs quantum dot layers using radiation induced current

Oshima, Takeshi; Nakamura, Tetsuya*; Sumita, Taishi*; Imaizumi, Mitsuru*; Sato, Shinichiro; Sugaya, Takeyoshi*; Matsubara, Koji*; Niki, Shigeru*; Mochizuki, Toru*; Okano, Yoshinobu*

no journal, , 

22 (Records 1-20 displayed on this page)