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Journal Articles

Core-level photoelectron spectroscopy study of UTe$$_{2}$$

Fujimori, Shinichi; Kawasaki, Ikuto; Takeda, Yukiharu; Yamagami, Hiroshi; Nakamura, Ai*; Homma, Yoshiya*; Aoki, Dai*

Journal of the Physical Society of Japan, 90(1), p.015002_1 - 015002_2, 2021/01

 Times Cited Count:0

Journal Articles

Eco-friendly carboxymethyl cellulose nanofiber hydrogels prepared via freeze cross-linking and their applications

Sekine, Yurina; Nankawa, Takuya; Yunoki, Shunji*; Sugita, Tsuyoshi; Nakagawa, Hiroshi; Yamada, Teppei*

ACS Applied Polymer Materials (Internet), 2(12), p.5482 - 5491, 2020/12

We developed a cross-linking method using freeze concentration and used it to synthesize a new type of carboxymethyl cellulose nanofiber (CMCF) hydrogel with high compressive strength ($$>$$ 80 MPa) and high compressive recoverability. The hydrogels were prepared by adding an aqueous solution of citric acid (CA) to a frozen CMCF sol and then thawing the sol. The reaction between the freeze-concentrated CMCF and CA created a rigid porous structure that reflected the ice crystal structure. Their cross-linked structure has a high stability to compressive stress. Bentonite was immobilized on a CMCF hydrogel by adding bentonite to the CMCF sol before freeze cross-linking. The CMCF-bentonite hydrogel showed high adsorptivity for chemical dyes. The physically cross-linked CMCF hydrogels are non-toxic, metal-free, and simple to prepare, and thus they may be useful as sustainable materials in various fields.

Journal Articles

Lens dosimetry study in $$^{90}$$Sr+$$^{90}$$Y beta field; Full-face mask respirator shielding and dosemeter positioning

Tsujimura, Norio; Hoshi, Katsuya; Yamazaki, Takumi; Momose, Takumaro; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

KEK Proceedings 2020-5, p.21 - 28, 2020/11

Journal Articles

Measurements of the doses of eye lens for the workers of Fukushima Daiichi Nuclear Power Plant

Yokoyama, Sumi*; Ezaki, Iwao*; Tatsuzaki, Hideo*; Tachiki, Shuichi*; Hirao, Kazushige*; Aoki, Katsunori; Tanimura, Yoshihiko; Hoshi, Katsuya; Yoshitomi, Hiroshi; Tsujimura, Norio

Radiation Measurements, 138, p.106399_1 - 106399_5, 2020/11

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

Journal Articles

Relationship between the microstructure and local corrosion properties of weld metal in austenitic stainless steels

Tokita, Shun*; Kadoi, Kota*; Aoki, So; Inoue, Hiroshige*

Corrosion Science, 175, p.108867_1 - 108867_8, 2020/10

 Times Cited Count:1 Percentile:100(Materials Science, Multidisciplinary)

The purpose of this study is to evaluate the corrosion resistance of weld metal by electrochemical methods and discuss the relationship between microstructure and corrosion resistance. Intergranular and pitting corrosion resistances were measured using electrochemical potentiokinetic reactivation (EPR) test and pitting potential measurement respectively. The reactivation ratio and pitting potential corresponded to its chemical composition. The specimens containing more Cr and Mo showed higher resistance. In the EPR test, the dendrite core with a relatively low Cr content was corroded. In the pitting corrosion test, Nb carbide became the initiation site of pitting corrosion which propagated along the cell structure.

Journal Articles

Proliferation resistance evaluation of an HTGR transuranic fuel cycle using PRAETOR code

Aoki, Takeshi; Chirayath, S. S.*; Sagara, Hiroshi*

Annals of Nuclear Energy, 141, p.107325_1 - 107325_7, 2020/06

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

The proliferation resistance (PR) of an inert matrix fuel (IMF) in the transuranic nuclear fuel cycle (NFC) of a high temperature gas cooled reactor is evaluated relative to the uranium and plutonium mixed-oxide (MOX) NFC of a light water reactor using PRAETOR code and sixty-eight input attributes. The objective is to determine the impacts of chemical stability of IMF and fuel irradiation on the PR. Specific material properties of the IMF, such as lower plutonium content, carbide ceramics coating, and absence of $$^{235}$$U, contribute to enhance its relative PR compared to MOX fuel. The overall PR value of the fresh IMF (an unirradiated direct use material with a one-month diversion detection timeliness goal) is nearly equal to that of the spent MOX fuel (an irradiated direct use nuclear material with a three-month diversion detection timeliness goal). Final results suggest a reduced safeguards inspection frequency to manage the IMF.

Journal Articles

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Plant, 2; Field study using humanoid phantoms

Tsujimura, Norio; Hoshi, Katsuya; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

Radiation Measurements, 134, p.106305_1 - 106305_5, 2020/06

 Times Cited Count:1 Percentile:28.06(Nuclear Science & Technology)

Journal Articles

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Plant, 1; Laboratory study on the dosemeter position and the shielding effect of full face mask respirators

Hoshi, Katsuya; Yoshitomi, Hiroshi; Aoki, Katsunori; Tanimura, Yoshihiko; Tsujimura, Norio; Yokoyama, Sumi*

Radiation Measurements, 134, p.106304_1 - 106304_5, 2020/06

 Times Cited Count:1 Percentile:28.06(Nuclear Science & Technology)

In FY 2017, the Japanese Nuclear Regulatory Agency (NRA) established the Radiation Safety Research Promotion Fund for funding projects on nuclear safety regulation, and adopted the two-year research project entitled "Study on standard eye lens monitoring, suitable dose management and radiation protection for nuclear and medical workers". The study is a two-phase study: a laboratory study on the eye lens dosemeter's characteristics to photons, and a field study executed at actual workplaces at Fukushima Daiichi Nuclear Power Station. This paper summarizes the results of the first-phase study, which was designed to clarify the eye lens dosemeter positioning and the shielding effect of full face mask respirators used at the station. No marked difference was observed in readings of the dosemeters attached on the different positions on the head phantom. Two types of full face mask respirators provided insignificant shielding effect for photons of 83 keV to 662 keV.

Journal Articles

A Remote continuous air monitoring system for measuring airborne alpha contamination

Morishita, Yuki; Usami, Hiroshi; Furuta, Yoshihiro; Aoki, Katsunori; Tsurudome, Koji; Hoshi, Katsuya; Torii, Tatsuo

Radiation Protection Dosimetry, 189(2), p.172 - 181, 2020/04

 Times Cited Count:0 Percentile:100(Environmental Sciences)

We developed a remote continuous air monitoring (RCAM) system. The RCAM system consisted of a personal air monitor and a robot. The personal air monitor (poCAMon, SARAD, Germany) had a 400 mm$$^{2}$$ ion-injected silicon detector and a membrane air filter with 25 mm-diameter. The personal air monitor provides the alpha energy spectra for any measurement time interval. Demonstration measurements were taken underground at the Mizunami Underground Research Laboratory (MIU) and at a poorly ventilated concrete building. The RCAM system was remotely operated and successfully measured the $$^{222}$$Rn progeny even though the relative humidity (RH) was almost 100%. In the measured alpha spectra, the peaks of $$^{218}$$Po (6.0 MeV alpha) and $$^{214}$$Po (7.7 MeV alpha) were clearly identified. Our developed monitor is promising for alpha dust monitoring in a high gamma-ray environment or contaminated areas where a worker cannot safely physically enter.

Journal Articles

Hard X-ray photoelectron spectroscopy study of Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$

Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Kawasaki, Ikuto; Okane, Tetsuo; Yamagami, Hiroshi; Yaita, Tsuyoshi; Harii, Kazuya; Ieda, Junichi; Okayasu, Satoru; et al.

JPS Conference Proceedings (Internet), 30, p.011192_1 - 011192_6, 2020/03

High energy X-ray photoelectron spectroscopy (HAXPES) measurements were carried out for the Spin Seebeck system Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$(YIG). This system was found to show anomalous Hall effect, possible due to the formation of intermetallic compounds between Fe$$^{3+}$$ and Pt. To reveal this possibility, we have measured the Fe 1s photoelectron peaks by using HAXPES. It was found that the Fe ions consist of Fe$$^{3+}$$ in YIG and metallic Fe. The formation of the metallic state is consistent with the proposed origin of the anomalous Hall effect. Other spectra such as Pt 4f will be presented at the conference.

JAEA Reports

On-site training using JMTR and related facilities in FY2018

Eguchi, Shohei; Nakano, Hiroko; Otsuka, Noriaki; Nishikata, Kaori; Nagata, Hiroshi; Ide, Hiroshi; Kusunoki, Tsuyoshi

JAEA-Review 2019-012, 22 Pages, 2019/10

JAEA-Review-2019-012.pdf:3.37MB

A practical training course using the JMTR and other research infrastructures was held from July 31st to August 7th in 2018 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 11 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2018 is reported in this paper.

Journal Articles

Electronic structure of UTe$$_2$$ studied by photoelectron spectroscopy

Fujimori, Shinichi; Kawasaki, Ikuto; Takeda, Yukiharu; Yamagami, Hiroshi; Nakamura, Ai*; Homma, Yoshiya*; Aoki, Dai*

Journal of the Physical Society of Japan, 88(10), p.103701_1 - 103701_5, 2019/10

 Times Cited Count:6 Percentile:28.59(Physics, Multidisciplinary)

Journal Articles

Novel bond stress evaluation technique using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Mukai, Tomohisa*

Konkurito Kozobutsu No Hihakai Kensa Shimpojiumu Hobunshu, 6, p.343 - 348, 2018/08

no abstracts in English

Journal Articles

Non-destructive bond stress evaluation of bending and shear deformed reinforced concrete structure using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Satake, Kosuke*; Kanematsu, Manabu*; Koyama, Taku*; Niwa, Akinobu*; Kabayama, Kenji*; Mukai, Tomohisa*; Kawasaki, Takuro; Harjo, S.

Hihakai Kensa, 67(4), p.180 - 186, 2018/04

The bond behavior between rebar and concrete under bending moment was investigated by measuring the stress distribution in the two-dimensionally distributed rebars embedded in the reinforced concrete (RC) beam using neutron diffraction. The stress distributions in both of the main rebar and the transverse stirrups embedded in concrete were successfully measured at the fixed measurement configuration without any sample rotations, by suggesting a simple measurement technique on the premise that the transverse restriction from the surrounding concrete to the main rebar is negligible. The bending and shear fracture behavior of the RC beam specimen was predicted by comparing changes in the stress distribution in the rebars measured by neutron diffraction with respect to the applied stress, with the macroscopic deformation measured by strain gauges fixed on the concrete surface. In this study, it was found that the neutron diffraction technique can be a useful technique to evaluate not only the anchorage performance but also the bending behavior of the RC beam.

JAEA Reports

On-site training using JMTR and related facilities in FY2017

Eguchi, Shohei; Shibata, Hiroshi; Imaizumi, Tomomi; Nagata, Hiroshi; Tanimoto, Masataka; Kusunoki, Tsuyoshi

JAEA-Review 2017-032, 26 Pages, 2018/02

JAEA-Review-2017-032.pdf:2.44MB

A practical training course using the JMTR and other research infrastructures was held from July 24th to August 4th in 2017 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 10 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2017 is reported in this paper.

Journal Articles

Nondestructive measurement of bond stress distribution of reinforced concrete using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Mukai, Tomohisa*

Konkurito Kozobutsu No Hoshu, Hokyo, Appuguredo Rombun Hokokushu, 17, p.179 - 184, 2017/10

no abstracts in English

Journal Articles

Magnetic structure and quadrupolar order parameter driven by geometrical frustration effect in NdB$$_4$$

Yamauchi, Hiroki; Metoki, Naoto; Watanuki, Ryuta*; Suzuki, Kazuya*; Fukazawa, Hiroshi; Chi, S.*; Fernandez-Baca, J. A.*

Journal of the Physical Society of Japan, 86(4), p.044705_1 - 044705_9, 2017/04

 Times Cited Count:6 Percentile:38.74(Physics, Multidisciplinary)

Neutron diffraction experiments have been carried out to characterize the magnetic structures and order parameters in an intermediate phase of NdB$$_4$$ showing the successive phase transitions at $$T_{rm 0} = 17.2$$ K, $$T_{rm N1} = 7.0$$ K, and $$T_{rm N2} = 4.8$$ K. The observed patterns in phase II ($$T_{rm N1} < T < T_{rm 0}$$) are successfully explained by postulating a planar structure with static magnetic moments in the tetragonal $$ab$$-plane. We have found that the magnetic structure in phase II can be uniquely determined to be a linear combination of noncolinear "all-in/all-out"-type and "vortex"-type antiferromagnetic structures. We propose that the quadrupolar interaction holds the key to stabilizing the noncollinear magnetic structure and quadrupolar order. Here, the frustration in the Shastry - Sutherland lattice would play an essential role in suppressing the dominance of the magnetic interaction.

JAEA Reports

On-site training using JMTR and related facilities in FY2016

Eguchi, Shohei; Takemoto, Noriyuki; Shibata, Hiroshi; Tanimoto, Masataka; Kusunoki, Tsuyoshi

JAEA-Review 2017-007, 32 Pages, 2017/03

JAEA-Review-2017-007.pdf:3.19MB

A practical training course using the JMTR and other research infrastructures was held from July 25th to August 5th in 2016 for domestic and foreign young researchers and engineers. This course aims to enlarge the number of high-level nuclear researchers/engineers in Japan and foreign countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 13 young researchers and engineers joined the course from 7 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training and technical tour of nuclear facilities on nuclear energy. At the end of the course, the trainees discussed the energy policy and prospect of each country, each country's research reactor, and trainee's current research. The content of this course in FY 2016 is reported in this paper.

Journal Articles

Structural engineering studies on reinforced concrete structure using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Mukai, Tomohisa*; Harjo, S.

Materials Research Proceedings, Vol.2, p.25 - 30, 2017/00

 Times Cited Count:1 Percentile:47.23

It has been demonstrated in our past studies that neutron diffraction can be an alternative method to conventional strain gauge for measuring the stress distribution along rebar embedded in concrete. The current study investigated the possibility of the bond stress evaluation using neutron diffraction in order to find further capability of neutron diffraction for the structural engineering study on the reinforced concrete structure. Several peaks appeared in the bond stress distribution measured by neutron diffraction, showing the inhomogeneous bond variation along the embedded rebar. This result suggests that the neutron diffraction technique with high spacial resolution makes it possible to catch local bond resistance caused by the transverse ribs. The bond stress distribution measured by the neutron diffraction technique is expected to bring detailed understanding of the bond mechanism between rebar and concrete for the reinforced concrete structure.

Journal Articles

Three-dimensional electronic structures and the metal-insulator transition in Ruddlesden-Popper iridates

Yamasaki, Atsushi*; Fujiwara, Hidenori*; Tachibana, Shoichi*; Iwasaki, Daisuke*; Higashino, Yuji*; Yoshimi, Chiaki*; Nakagawa, Koya*; Nakatani, Yasuhiro*; Yamagami, Kohei*; Aratani, Hidekazu*; et al.

Physical Review B, 94(11), p.115103_1 - 115103_10, 2016/11

AA2016-0587.pdf:2.55MB

 Times Cited Count:12 Percentile:35.1(Materials Science, Multidisciplinary)

In this study, we systematically investigate three-dimensional(3D) momentum-resolved electronic structures of Ruddlesden-Popper-type iridium oxides Sr$$_{n+1}$$Ir$$_{n}$$O$$_{3n+1}$$ using soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO$$_{2}$$-plane structure. This transition occurs when the spin-orbit-coupled $$j_{eff}$$ = 1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. By scanning the photon energy over 350 eV, we reveal the 3D Fermi surface in SrIrO$$_{3}$$ and $$k_{z}$$-dependent oscillations of photoelectron intensity in Sr$$_{3}$$Ir$$_{2}$$O$$_{7}$$. To corroborate the physics deduced using low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful complementary technique, as this method surveys more than one whole Brillouin zone and provides a panoramic view of electronic structures.

344 (Records 1-20 displayed on this page)