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JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2019

Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Hanamuro, Takahiro; Shimada, Akiomi; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Research 2020-011, 67 Pages, 2020/10

JAEA-Research-2020-011.pdf:3.87MB

This annual report documents the progress of research and development (R&D) in the 5th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) 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, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. The current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Current status and prospects of FT and (U-Th)/He dating laboratory at Japan Atomic Energy Agency

Sueoka, Shigeru; Shimada, Koji; Kanno, Mizuho; Yokoyama, Tatsunori

Fisshion, Torakku Nyusureta, (33), p.15 - 18, 2020/10

no abstracts in English

Journal Articles

${it In situ}$ WB-STEM observation of dislocation loop behavior in reactor pressure vessel steel during post-irradiation annealing

Du, Y.*; Yoshida, Kenta*; Shimada, Yusuke*; Toyama, Takeshi*; Inoue, Koji*; Arakawa, Kazuto*; Suzudo, Tomoaki; Milan, K. J.*; Gerard, R.*; Onuki, Somei*; et al.

Materialia, 12, p.100778_1 - 100778_10, 2020/08

In order to ensure the integrity of the reactor pressure vessel in the long term, it is necessary to understand the effects of irradiation on the materials. In this study, irradiation-induced dislocation loops were observed in neutron-irradiated reactor pressure vessel specimens during annealing using our newly developed WB-STEM. It was confirmed that the proportion of $$<100>$$ loops increased with increasing annealing temperature. We also succeeded in observing the phenomenon that two $$frac{1}{2}$$$$<111>$$ loops collide into a $$<100>$$ loop. Moreover, a phenomenon in which dislocation loops decorate dislocations was also observed, and the mechanism was successfully explained by molecular dynamics simulation.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2020)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Koji; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; Komatsu, Tetsuya; Yokoyama, Tatsunori; et al.

JAEA-Review 2020-010, 46 Pages, 2020/07

JAEA-Review-2020-010.pdf:1.89MB

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 Japan Atomic Energy Agency (JAEA), in fiscal year 2020. The objectives and contents in fiscal year 2020 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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.

Journal Articles

Kinetic inductance neutron detector operated at near critical temperature

Vu, TheDang; Nishimura, Kazuma*; Shishido, Hiroaki*; Harada, Masahide; Oikawa, Kenichi; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.

Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07

Journal Articles

Development of laser cutting technology of thick steel plates for nuclear facilities

Tamura, Koji*; Toyama, Shinichi

Nippon Genshiryoku Gakkai-Shi, 62(5), p.268 - 271, 2020/05

The laser cutting technology is expected to be a promising candidate for the decommissioning measure of nuclear facilities, because it has a lot of advantage such as its high controllability and excellent suitability to remote handling by robot arm, etcetera. This report describes the recent result from laser cutting technology development for thick steel materials summarizing the cutting demonstration of 300 mm thick steels and dummy pressure vessel, the analysis of cutting condition of thick steel cutting, the observation of cutting process, remote controlled cutting system, the cutting in pile of steels by the system, and countermeasure for fume produce by cutting process.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2018

Ishimaru, Tsuneari; Ogata, Nobuhisa; Hanamuro, Takahiro; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Shimada, Koji; Watanabe, Takahiro; Saiga, Atsushi; et al.

JAEA-Research 2019-006, 66 Pages, 2019/11

JAEA-Research-2019-006.pdf:4.39MB

This annual report documents the progress of research and development (R&D) in the 4th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) 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, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Temperature dependent characteristics of neutron signals from a current-biased Nb nanowire detector with $$^{10}$$B converter

Vu, TheDang; Iizawa, Yuki*; Nishimura, Kazuma*; Shishido, Hiroaki*; Kojima, Kenji*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; et al.

Journal of Physics; Conference Series, 1293, p.012051_1 - 012051_9, 2019/10

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2019)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Hanamuro, Takahiro; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Review 2019-010, 46 Pages, 2019/09

JAEA-Review-2019-010.pdf:2.45MB

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 Japan Atomic Energy Agency, in fiscal year 2019. The objectives and contents in fiscal year 2019 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.

Journal Articles

Laser cutting technology of thick steel components; Advanced technology developed at the era of decommissioning

Tamura, Koji*; Toyama, Shinichi

Nippon Genshiryoku Gakkai-Shi, 61(5), p.413 - 415, 2019/05

In decommissioning of nuclear reactors, it is necessary to disassemble the nuclear reactor structure. In addition to the conventional cutting method, the laser method has many advantages such as remote controllability and no need for replacement parts such as blades, which can be a powerful choice. Nuclear reactor structure such as a pressure vessel are made of steel materials with a thickness exceeding 100 mm, and the laser method has poor knowledge and experience in cutting such thick steel materials. Therefore, as a result of trial cutting of steel materials under various cutting conditions with the high power fiber laser which is progressively available nowadays, it has been demonstrated that laser cutting is also possible for thick plates such as those used in nuclear reactors, and cutting of thick steel plates. We also developed the cutting technology using remote control using a robot in order to apply it to the decommissioning of thick steel cutting on the spot.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:86 Percentile:0.14(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

 Times Cited Count:2 Percentile:60.07(Physics, Condensed Matter)

Journal Articles

Outline and implementation status of decommissioning plan of JRR-4

Ishikuro, Yasuhiro; Nemoto, Tsutomu; Yamada, Yusuke; Oyama, Koji

Nippon Hozen Gakkai Dai-15-Kai Gakujutsu Koenkai Yoshishu, p.501 - 505, 2018/07

After operating until December 2010, JRR-4 was under periodical self-inspection for the next operation. After that, it suffered from the Great East Japan Earthquake on March 11, 2011. But it recovered almost a year later. However, we determined to decommission JRR-4 in September 2013. After that, we received the approval of the decommissioning plan of JRR-4 on June 7, 2017. And we received the approval of the change of the safety regulations related to it. Subsequently JRR-4 was shifted to decommission phase in December 2017. This report describes the outline of the decommissioning plan of JRR-4 and the implementation status.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Improvement of estimation of $$^{131}$$I concentrations in the air using data measured by monitoring posts applied by determination of passing-through time of plume using noble gas counts

Yamada, Junya; Hashimoto, Makoto; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

Hoken Butsuri, 52(1), p.5 - 12, 2017/03

The purpose of this study is to improve a quick method for estimation of $$^{131}$$I concentrations in the air using data measured by monitoring posts in case that a nuclear disaster occurs. In this method, $$^{131}$$I concentrations were estimated by multiplying $$^{131}$$I count rates of cloud-shine measured with NaI (Tl) detector by concentration conversion factor. A previous study suggested that it was difficult to determine passing-through time of plume from temporal change of $$^{131}$$I count rates or dose rate. Our study applies the method for estimating passing-through time of plume from temporal change of noble gas counts. The $$^{131}$$I concentrations in the air at Oarai center, Japan Atomic Energy Agency resulting from the accident at the Fukushima Daiichi Nuclear Power Plant were estimated by proposal technique. The result of comparison of this method with sampling method for $$^{131}$$I concentrations in the air were within factor 3.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2015

Ishimaru, Tsuneari; Umeda, Koji*; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Yokoyama, Tatsunori; Fujita, Natsuko; Shimizu, Mayuko; et al.

JAEA-Research 2016-023, 91 Pages, 2017/02

JAEA-Research-2016-023.pdf:13.33MB

This annual report documents the progress of research and development (R&D) in the 1st fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) 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, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Predoping effects of boron and phosphorous on arsenic diffusion along grain boundaries in polycrystalline silicon investigated by atom probe tomography

Takamizawa, Hisashi; Shimizu, Yasuo*; Inoue, Koji*; Nozawa, Yasuko*; Toyama, Takeshi*; Yano, Fumiko*; Inoue, Masao*; Nishida, Akio*; Nagai, Yasuyoshi*

Applied Physics Express, 9(10), p.106601_1 - 106601_4, 2016/10

 Times Cited Count:0 Percentile:100(Physics, Applied)

Journal Articles

Calculation of conversion factor for estimation of $$^{131}$$I concentrations in the air from pulse-height distribution observed by NaI(Tl) detector in monitoring posts

Yamada, Junya; Hashimoto, Makoto; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

Radioisotopes, 65(10), p.403 - 408, 2016/10

The purpose of this study is to develop a quick method for estimation of $$^{131}$$I concentrations in the air using data measured by monitoring posts. In this method, $$^{131}$$I concentrations were estimated by multiplying $$^{131}$$I count rates at the full-energy peak measured with a NaI(Tl) detector by a concentration conversion factor. The concentration conversion factor for monitoring posts in JAEA Oarai Center was calculated with an EGS5 Monte Carlo code. As a result, the concentration conversion factor for an infinite-air-source was 25.7 Bq/m$$^{3}$$/cps.

Journal Articles

Recent progress in the chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

JAEA-Conf 2015-002, p.319 - 329, 2016/02

Journal Articles

Triangle and concave pentagon electrodes for an improved broadband frequency response of stripline beam position monitors

Shobuda, Yoshihiro; Chin, Y. H.*; Takata, Koji*; Toyama, Takeshi*; Nakamura, Keigo*

Physical Review Accelerators and Beams (Internet), 19(2), p.021003_1 - 021003_15, 2016/02

 Times Cited Count:1 Percentile:100(Physics, Nuclear)

The frequency domain performance of a stripline beam position monitor depends largely on the longitudinal shape of its electrode. To attain a good impedance matching along the electrode, it needs to be precisely bent down toward its downstream in proportion to its width. In this report, we first propose a triangle electrode for easy fabrication and set-up. Theoretical and simulation results show that the simple triangle electrode has a remarkably flatter frequency response than the rectangle one. The frequency response, in particular at high frequencies, can be further improved by attaching an "apron" plate, perpendicular to the upstream edge of the electrode. The overshooting of the frequency response at low frequency can be eliminated by replacing the straight sidelines of the triangle by three-point polylines. We found that the concave pentagon electrode achieves a wide and flat frequency response up to about $$4$$ GHz for the J-PARC Main Ring.

214 (Records 1-20 displayed on this page)