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Journal Articles

Investigation of hydration and adsorption structures on clay minerals of radium by EXAFS

Yamaguchi, Akiko; Nagata, Kojiro*; Tanaka, Kazuya; Kobayashi, Keita; Kobayashi, Toru; Shimojo, Kojiro; Tanida, Hajime; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.

Hosha Kagaku, (45), p.28 - 30, 2022/03

no abstracts in English

Journal Articles

Hydration structures of barium ions; ${it Ab initio}$ molecular dynamics simulations using the SCAN meta-GGA density functional and EXAFS spectroscopy studies

Yamaguchi, Akiko; Kobayashi, Keita; Takahashi, Yoshio*; Machida, Masahiko; Okumura, Masahiko

Chemical Physics Letters, 780, p.138945_1 - 138945_5, 2021/10

 Times Cited Count:1 Percentile:0.01(Chemistry, Physical)

no abstracts in English

Journal Articles

Fundamental study on scheduling of inspection process for fast reactor plants

Suzuki, Masaaki*; Ito, Mari*; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru

2020 9th International Congress on Advanced Applied Informatics (IIAI-AAI 2020), p.797 - 801, 2021/07

Journal Articles

Proposal of maintenance rationalization for next-generation fast reactors based on the analysis of the prolonged maintenance of the prototype fast-breeder reactor in Japan, "Monju", 1; Analysis of plant schedule of "Monju" in cold shutdown

Hashidate, Ryuta; Toyota, Kodai; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru

Hozengaku, 19(4), p.115 - 122, 2021/01

In order to improve both safety and economic efficiency of a nuclear power plant, it is necessary to realize rational maintenance based on characteristics of the plant. The prototype fast-breeder reactor in Japan, Monju, spent most of the year for the maintenance. Thus, it is important to identify causes of the prolonged maintenance of Monju and to investigate countermeasures for implementation of rational maintenance of next-generation fast reactors. In this study, the authors investigated the causes of the prolonged maintenance of Monju during reactor cold shutdown based on the plant schedule of Monju. In addition, we proposed the maintenance optimization idea for next-generation fast reactors to solve the revealed issues.

Journal Articles

Role of advection in atmospheric ammonia; A Case study at a Japanese lake basin influenced by agricultural ammonia sources

Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.

Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12

 Times Cited Count:1 Percentile:10.68(Environmental Sciences)

The dry and wet depositions of atmospheric ammonia (NH$$_{3}$$) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH$$_{3}$$ in Asian countries, are known to cause high spatial and seasonal variation of NH$$_{3}$$ and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH$$_{3}$$ concentration in basin scale are not completely understood for regulation in NH$$_{3}$$ emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH$$_{3}$$ concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH$$_{3}$$ concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH$$_{3}$$ emission inventory based on temperature-driven volatilization process. Comparing monthly NH$$_{3}$$ concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH$$_{3}$$ from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH$$_{3}$$ is known to be closely related to the ecological processes such as phytoplankton blooming.

JAEA Reports

Prototype fast breeder reactor Monju; Its history and achievements (Translated document)

Mitsumoto, Rika; Hazama, Taira; Takahashi, Keita; Kondo, Satoru

JAEA-Technology 2019-020, 167 Pages, 2020/03

JAEA-Technology-2019-020.pdf:21.06MB
JAEA-Technology-2019-020-high-resolution1.pdf:47.3MB
JAEA-Technology-2019-020-high-resolution2.pdf:34.99MB
JAEA-Technology-2019-020-high-resolution3.pdf:48.74MB
JAEA-Technology-2019-020-high-resolution4.pdf:47.83MB
JAEA-Technology-2019-020-high-resolution5.pdf:18.35MB
JAEA-Technology-2019-020-high-resolution6.pdf:49.4MB
JAEA-Technology-2019-020-high-resolution7.pdf:39.78MB

The prototype fast breeder reactor Monju has produced valuable technological achievements through design, construction, operation and maintenance over half a century since 1968. This report compiles the reactor technologies developed for Monju, including the areas: history and major achievements, design and construction, commissioning, safety, reactor physics, fuel, systems and components, sodium technology, materials and structures, operation and maintenance, and accidents and failures.

Journal Articles

Measurement of ion species in high current ECR H$$^+$$/D$$^+$$ ion source for IFMIF (International Fusion Materials Irradiation Facility)

Shinto, Katsuhiro; Sen$'e$e, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; Ichimiya, Ryo; Ihara, Akira; Ikeda, Yukiharu; Kasugai, Atsushi; et al.

Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02

 Times Cited Count:8 Percentile:45.08(Instruments & Instrumentation)

Journal Articles

Present status of the injector for IFMIF Linear Prototype Accelerator (LIPAc)

Shinto, Katsuhiro; Ichikawa, Masahiro; Takahashi, Hiroki; Kondo, Keitaro; Kasugai, Atsushi; Gobin, R.*; Sen$'e$e, F.*; Chauvin, N.*; Ayala, J.-M.*; Marqueta, A.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.493 - 495, 2015/09

Development of the prototype accelerator (LIPAc) for the engineering validation of the International Fusion Materials Irradiation Facility (IFMIF) which is an accelerator driven neutron source has been progressed at Rokkasho. The LIPAc is a deuteron linear accelerator consisting of an injector, a radio-frequency quadrupole (RFQ) linac and a superconducting linac. The objective of LIPAc is to produce a CW beam with the energy and current of 9 MeV and 125 mA, respectively. The injector was developed at CEA/Saclay and succeeded to produce CW proton and deuteron beams of 100 keV/140 mA by autumn 2012. After the test at CEA/Saclay, the injector was shipped to the International Fusion Energy Research Centre (IFERC) in Rokkasho, Aomori and started to reassemble from the end of 2013. It was successfully produced proton beams in November 2014 at Rokkasho. While the ion source conditioning was done, the beam test was progressed. In this paper, the present status of the LIPAc injector at Rokkasho with some experimental results will be presented.

Journal Articles

Progress of the high current Prototype Accelerator for IFMIF/EVEDA

Okumura, Yoshikazu; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; Gobin, R.*; Harrault, F.*; Heidinger, R.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.203 - 205, 2015/09

Under the framework of Broader Approach (BA) agreement between Japan and Euratom, IFMIF/EVEDA project was launched in 2007 to validate the key technologies to realize IFMIF. The most crucial technology to realize IFMIF is two set of linear accelerator each producing 125mA/CW deuterium ion beams up to 40MeV. The prototype accelerator, whose target is 125mA/CW deuterium ion beam acceleration up to 9MeV, is being developed in International Fusion Research Energy Center (IFERC) in Rokkasho, Japan. The injector developed in CEA Saclay was delivered in Rokkasho in 2014, and is under commissioning. Up to now, 100keV/120mA/CW hydrogen ion beams and 100keV/90mA/CW duty deuterium ion beams are successfully produced with a low beam emittance of 0.21 $$pi$$.mm.mrad (rms, normalized). Delivery of RFQ components will start in 2015, followed by the installation of RF power supplies in 2015.

Journal Articles

Numerical analysis of air-hydrogen mixture flow in rectangular indoor space with ventilators

Sugiyama, Hitoshi*; Takahashi, Keita*; Kato, Naoto*; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro

Jidosha Gijutsukai Gakujutsu Koenkai Zensatsushu, (109-14), p.5 - 10, 2014/10

Numerical analysis has been performed for vertical buoyant flow of air-hydrogen mixture in rectangular indoor space with ventilators. The unsteady and laminar flow has been calculated by using the coupled conservation equations of hydrogen and momentum. Calculated results are compared with the experiment data of hydrogen concentration and velocity profile in order to confirm the validity of the presented numerical method and clarify the mechanism of hydrogen dispersion. Although agreement is certainly not perfect in all detail, the main features are reasonably reproduced. Adding to this, calculated results suggest that hydrogen concentration depends on Froude number.

JAEA Reports

Verification of improvement of the casting process in metal melting system

Tohei, Toshio; Nakashio, Nobuyuki; Osugi, Takeshi; Ishikawa, Joji; Mizoguchi, Takafumi; Hanawa, Ritsu; Someya, Keita*; Takahashi, Kenji*; Iseda, Hirokatsu; Kozawa, Kazushige; et al.

JAEA-Technology 2010-008, 28 Pages, 2010/06

JAEA-Technology-2010-008.pdf:5.0MB

The Waste Volume Reduction Facility (WVRF) was constructed for volume reduction and the chemical stabilization of the low level radioactive waste in the Nuclear Science Research Institute of JAEA. The metal melting system in the WVRF treats radioactive metal waste. From the experience of trial operations, the improvement has conducted on the casting process in the metal melting system. The performance of the improved casting process was verified through the trial operations from Oct. 2008. In this report, we describe the reduction of the processing time, of the utilities consumption, of the load of maintenance on the improved casting process.

JAEA Reports

Improvement of the casting process in the metal melting system

Tohei, Toshio; Someya, Keita; Takahashi, Kenji; Iseda, Hirokatsu; Kozawa, Kazushige; Momma, Toshiyuki

JAEA-Technology 2009-031, 29 Pages, 2009/06

JAEA-Technology-2009-031.pdf:21.66MB

The Waste Volume Reduction Facility (WVRF) was constructed for volume reduction and the chemical stabilization of the low level radioactive waste (LLW). The metal melting system in the WVRF treats radioactive metal waste. This system has been conducted commissioning since the FY 2003. It was found, from the experience of commissioning, that the improvement of casting process in the metal melting system can be reduced the processing cost, maintenance load, and dose to workers. We planed modification of the device, and embodied from FY 2006 to FY 2007. As a result, we properly improved the casting process. In this report, we describe the idea for improvement of the casting process, the detail of improvement and the estimate of improvement.

Journal Articles

Effects of locally targeted heavy-ion and laser microbeam on root hydrotropism in ${it Arabidopsis thaliana}$

Miyazawa, Yutaka*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; et al.

Journal of Radiation Research, 49(4), p.373 - 379, 2008/07

 Times Cited Count:24 Percentile:61.06(Biology)

We examined the role of root cap and elongation zone cells in root hydrotropism using heavy-ion and laser microbeam. Heavy-ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporary suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy-ion broad-beam irradiation suppressed ${it de novo}$ expression of ${it INDOLE ACETIC ACID 5}$ gene, but not ${it MIZU-KUSSEI1}$ gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that ${it de novo}$ gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.

Journal Articles

Functional analysis of root elongation zone in hydrotropism in ${it Arabidopsis}$ using heavy-ion microbeam

Miyazawa, Yutaka*; Sakashita, Tetsuya; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 116, 2008/03

We examined the role of root cap and elongation zone cells in root hydrotropism of ${it Arabidopsis thaliana}$ using heavy ion and laser microbeam. Heavy ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy ion broad beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.

JAEA Reports

Construction, management and operation on advanced volume reduction facilities

Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.

JAEA-Technology 2007-038, 189 Pages, 2007/07

JAEA-Technology-2007-038-01.pdf:15.13MB
JAEA-Technology-2007-038-02.pdf:38.95MB
JAEA-Technology-2007-038-03.pdf:48.42MB
JAEA-Technology-2007-038-04.pdf:20.53MB
JAEA-Technology-2007-038-05.pdf:10.44MB

The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.

Journal Articles

Charged-particle spectrometry using a pencil-beam DT neutron source for double-differential cross-section measurement

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Miyamaru, Hiroyuki*; Kubota, Naoyoshi; Takagi, Satoshi*; Shido, Shoichi*; Takahashi, Akito*; Nishitani, Takeo

Nuclear Instruments and Methods in Physics Research A, 568(2), p.723 - 733, 2006/12

 Times Cited Count:15 Percentile:72.54(Instruments & Instrumentation)

Deuteron-tritium (DT) neutron induced charged-particle emission double-differential cross section (DDXc) is quite important to estimate nuclear heating, material damages for a fusion reactor. In order to realize the accurate measurement of the DDXc data especially for light nuclei, we propose a unique spectrometer system and a data processing method in this paper. The spectrometer overcomes the fundamental difficulty of the DDXc measurement with a pencil-beam neutron source and a counter telescope consisting of silicon surface barrier detectors. A superior S/N ratio, fine energy and angular resolutions, a wide detection energy range, and a excellent particle discrimination are realized. In order to confirm the validity of the spectrometer, measurements of the emitted $$alpha$$-particle from $$^{27}$$Al(${it n,x$alpha$}$) reaction and the recoiled proton from $$^{1}$$H(${it n,n}$) reaction are carried out. Based on the results, we conclude the validity and the superiority of the present spectrometry technique.

JAEA Reports

Development of measurement technique for charged-particle emission double-differential cross section using pencil-beam neutron source (Cooperative research)

Kondo, Keitaro; Ochiai, Kentaro; Kubota, Naoyoshi; Nishitani, Takeo; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*

JAEA-Research 2006-016, 50 Pages, 2006/03

JAEA-Research-2006-016.pdf:6.25MB

Charged-particle emission double- differential cross section (DDXc) is quite important to estimate nuclear heating, material damages of a fusion reactor. We have developed a new technique for detailed measurement of DDXc. The technique overcomes fundamental difficulties of DDXc measurement with a pencil-beam neutron source and a counter telescope consisting of silicon surface barrier detectors. A superior S/N ratio, fine energy and angular resolutions, a wide detection energy range, and an excellent particle discrimination are realized together with a reasonable measurement time. In order to confirm the validity of the spectrometer, measurements of the emitted $$alpha$$-particle from $$^{27}$$Al(n,x$$alpha$$) reaction and the recoiled proton from $$^{1}$$H(n,n) reaction are carried out. Based on the results, we conclude the validity and the superiority of the present spectrometry technique.

Journal Articles

New approach to measure double-differential charged-particle emission cross sections of several materials for a fusion reactor

Kondo, Keitaro; Takagi, Satoshi*; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo

Fusion Engineering and Design, 81(8-14), p.1527 - 1533, 2006/02

 Times Cited Count:12 Percentile:64.95(Nuclear Science & Technology)

In a fusion reactor development, double-differential charged-particle emission cross sections(DDXc) are necessary to estimate nuclear heating and material damages of candidate materials irradiated with neutrons. Especially in light nuclei such as Be, Li, and C, nuclear reactions are complicated and difficult to estimate energy spectra of emitted particles based only on theoretical calculations Therefore development of a new technique for precise measurements of DDXc is quite important. Recently we successfully developed a new spectrometer for measurement of DDXc using a pencil-beam DT neutron source of FNS in JAERI. In the present study we carried out measurements of DDXc of $$^{9}$$Be, $$^{12}$$C, $$^{19}$$F, and $$^{27}$$Al using the spectrometer. The present technique was valid from the result of measurement for the $$^{27}$$Al(n,x$$alpha$$) reactions. Slight differences appeared between measured data and evaluation or previous experimental values for $$^{9}$$Be(n,x$$alpha$$) reactions at backward scattering angle and in lower energy region.

Journal Articles

Measurement of energetic charged particles produced in fusion materials with 14 MeV neutron irradiation

Ochiai, Kentaro; Kondo, Keitaro; Murata, Isao*; Miyamaru, Hiroyuki*; Kubota, Naoyoshi; Takahashi, Akito*; Nishitani, Takeo

Fusion Engineering and Design, 75-79, p.859 - 863, 2005/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The Fusion Neutronics Source (FNS) of JAERI currently carries out the measurements of energetic charged particles emitted from fusion materials irradiated with a well-collimated 14 MeV neutron beam. At the beginning, the double differential cross section beryllium was measured. We have measured proton, triton and a particle emitted from a beryllium sample of 100 $$mu$$m in thickness.The a particle and triton were produced by $$^{9}$$Be(n,$$alpha$$)$$^{6}$$He, $$^{9}$$Be(n,2n)2$$alpha$$ and $$^{9}$$Be(n,t)$$^{7}$$Li reactions respectively. Measured total reaction rates from the counts of a particles and tritons were 2.7$$times$$10$$^{-24}$$ and 6$$times$$10$$^{-27}$$/atom/neutron, respectively, which were consistent with the calculated values from the nuclear data JENDL-3.2.

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