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Journal Articles

Rotation of complex ions with ninefold hydrogen coordination studied by quasielastic neutron scattering and first-principles molecular dynamics calculations

Omasa, Yoshinori*; Takagi, Shigeyuki*; Toshima, Kento*; Yokoyama, Kaito*; Endo, Wataru*; Orimo, Shinichi*; Saito, Hiroyuki*; Yamada, Takeshi*; Kawakita, Yukinobu; Ikeda, Kazutaka*; et al.

Physical Review Research (Internet), 4(3), p.033215_1 - 033215_9, 2022/09

Journal Articles

Uranium chelating ability of decorporation agents in serum evaluated by X-ray absorption spectroscopy

Uehara, Akihiro*; Matsumura, Daiju; Tsuji, Takuya; Yakumaru, Haruko*; Tanaka, Izumi*; Shiro, Ayumi*; Saito, Hiroyuki*; Ishihara, Hiroshi*; Homma-Takeda, Shino*

Analytical Methods, 14(24), p.2439 - 2445, 2022/06

 Times Cited Count:1 Percentile:72.2(Chemistry, Analytical)

Journal Articles

Repeatable photoinduced insulator-to-metal transition in yttrium oxyhydride epitaxial thin films

Komatsu, Yuya*; Shimizu, Ryota*; Sato, Ryuhei*; Wilde, M.*; Nishio, Kazunori*; Katase, Takayoshi*; Matsumura, Daiju; Saito, Hiroyuki*; Miyauchi, Masahiro*; Adelman, J. R.*; et al.

Chemistry of Materials, 34(8), p.3616 - 3623, 2022/04

 Times Cited Count:3 Percentile:87.74(Chemistry, Physical)

Journal Articles

Volatilization of B$$_{4}$$C control rods in Fukushima Daiichi nuclear reactors during meltdown; B-Li isotopic signatures in cesium-rich microparticles

Fueda, Kazuki*; Takami, Ryu*; Minomo, Kenta*; Morooka, Kazuya*; Horie, Kenji*; Takehara, Mami*; Yamasaki, Shinya*; Saito, Takumi*; Shiotsu, Hiroyuki; Onuki, Toshihiko*; et al.

Journal of Hazardous Materials, 428, p.128214_1 - 128214_10, 2022/04

 Times Cited Count:2 Percentile:79.7(Engineering, Environmental)

Journal Articles

Time-resolved 3D visualization of liquid jet breakup and impingement behavior in a shallow liquid pool

Kimura, Fumihito*; Yamamura, Sota*; Fujiwara, Kota*; Yoshida, Hiroyuki; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*

Nuclear Engineering and Design, 389, p.111660_1 - 111660_11, 2022/04

 Times Cited Count:2 Percentile:91.04(Nuclear Science & Technology)

Journal Articles

Dispersive XAFS Study on the Laser-Induced Reduction of a Rh$$^{3+}$$ ion complex; Presence of a Rh$$^{+}$$ Intermediate in Direct Photoreduction

Saeki, Morihisa*; Matsumura, Daiju; Nakanishi, Ryuzo*; Yomogida, Takumi; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*

Journal of Physical Chemistry C, 126(12), p.5607 - 5616, 2022/03

 Times Cited Count:1 Percentile:61.27(Chemistry, Physical)

The reaction mechanism of the direct photoreduction of a Rh$$^{3+}$$ ion complex to a Rh$$^{0}$$ species induced by pulsed ultraviolet laser irradiation was studied using dispersive X-ray absorption fine structure (DXAFS) spectroscopy. The time-resolved X-ray absorption near edge structure (XANES) showed the absence of isosbestic points and suggested that more than two Rh$$^{n+}$$ species contribute toward the direct photoreduction of Rh$$^{3+}$$. Analysis of the time-resolved XANES data by singular value deposition showed that the direct photoreduction involves three Rh$$^{n+}$$ species. Multivariate curve resolution by alternating least-squares analysis (MCR-ALS) of the time-resolved XANES data gave pure spectra and concentration profiles of the three Rh$$^{n+}$$ species. The Rh$$^{n+}$$ species were assigned to Rh$$^{3+}$$, Rh$$^{+}$$, and Rh$$^{0}$$ species based on the features of the pure XANES spectra. The concentration profiles suggested that the direct photoreduction proceeds in the order of Rh$$^{3+}$$ $$rightarrow$$ Rh$$^{+}$$ $$rightarrow$$ Rh$$^{0}$$. A reaction mechanism, which was proposed involving photoreductions of Rh$$^{3+}$$ and Rh$$^{+}$$, photoinduced autocatalytic reductions of Rh$$^{3+}$$ and Rh$$^{+}$$, and photooxidation of Rh$$^{+}$$, well reproduced the concentration profiles of three Rh$$^{n+}$$ species.

Journal Articles

Improving the safety of the high temperature gas-cooled reactor "HTTR" based on Japan's new regulatory requirements

Hamamoto, Shimpei; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Sekita, Kenji; Watanabe, Shuji; Furusawa, Takayuki; Iigaki, Kazuhiko; et al.

Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03

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

Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, the Japan Atomic Energy Agency adapted High-Temperature engineering Test Reactor (HTTR) to meet the new regulatory requirements that began in December 2013. The safety and seismic classifications of the existing structures, systems, and components were discussed to reflect insights regarding High Temperature Gas-cooled Reactors (HTGRs) that were acquired through various HTTR safety tests. Structures, systems, and components that are subject to protection have been defined, and countermeasures to manage internal and external hazards that affect safety functions have been strengthened. Additionally, measures are in place to control accidents that may cause large amounts of radioactive material to be released, as a beyond design based accident. The Nuclear Regulatory Commission rigorously and appropriately reviewed this approach for compliance with the new regulatory requirements. After nine amendments, the application to modify the HTTR's installation license that was submitted in November 2014 was approved in June 2020. This response shows that facilities can reasonably be designed to meet the enhanced regulatory requirements, if they reflect the characteristics of HTGRs. We believe that we have established a reference for future development of HTGR.

Journal Articles

Fundamental study for decorporation of plutonium by chelating agents; Coordination analyses of simulated plutonium with chelating agents by X-ray absorption spectroscopy

Uehara, Akihiro*; Shuhui, X.*; Sato, Ryotaro*; Matsumura, Daiju; Tsuji, Takuya; Yakumaru, Haruko*; Shiro, Ayumi*; Saito, Hiroyuki*; Tanaka, Izumi*; Ishihara, Hiroshi*; et al.

X-sen Bunseki No Shimpo, 53, p.223 - 229, 2022/03

no abstracts in English

Journal Articles

Bayesian sparse modeling of extended X-ray absorption fine structure to determine interstitial oxygen positions in yttrium oxyhydride epitaxial thin film

Kumazoe, Hiroyuki*; Igarashi, Yasuhiko*; Iesari, F.*; Shimizu, Ryota*; Komatsu, Yuya*; Hitosugi, Taro*; Matsumura, Daiju; Saito, Hiroyuki*; Iwamitsu, Kazunori*; Okajima, Toshihiko*; et al.

AIP Advances (Internet), 11(12), p.125013_1 - 125013_5, 2021/12

 Times Cited Count:1 Percentile:19.54(Nanoscience & Nanotechnology)

Journal Articles

${it In situ}$ spectrometry of terrestrial gamma rays using portable germanium detectors in area of 80 km radius around the Fukushima Daiichi Nuclear Power Plant

Mikami, Satoshi; Tanaka, Hiroyuki*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Ochi, Kotaro; Uno, Kiichiro*; Matsuda, Norihiro; Saito, Kimiaki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(4), p.159 - 178, 2021/12

In order to know the background radiation level where the area affected by the Fukushima Daiichi Nuclear Power Plant accident in 2011, terrestrial gamma rays had been measured by using portable germanium detectors repeatedly from 2013 through 2019, at 370 locations within 80 km radius area centered on the Fukushima Daiichi Nuclear Power Plant. Radioactive concentrations of Uranium 238, Thorium 232, Potassium 40 and kerma rates in air due to terrestrial gamma rays were obtained at those locations based on the method of ICRU report 53. Averaged concentrations of $$^{238}$$U, $$^{232}$$Th and $$^{40}$$K were 18.8, 22.7, 428 Bq/kg, respectively, and kerma rate in air over the area was found to be 0.0402 $$mu$$Gy/h. The obtained kerma rates in air were compared to those reported in literatures. It was confirmed that the data were correlated with each other, and were agreed within the range of their uncertainty. This is because the kerma rate in air due to terrestrial gamma rays is depend on geology. The similar trend to previous findings was observed that the kerma rate in air at locations geologically classified as Mesozoic era, Granite and Rhyolite were statistically significantly higher than the others.

JAEA Reports

Impact assessment for internal flooding in HTTR (High temperature engineering test reactor)

Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji

JAEA-Technology 2021-014, 80 Pages, 2021/09


In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.

Journal Articles

Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*

Tetsu To Hagane, 107(9), p.760 - 768, 2021/09

 Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Observation of the angular momentum compensation by Barnett effect and NMR

Chudo, Hiroyuki; Imai, Masaki; Matsuo, Mamoru; Maekawa, Sadamichi; Saito, Eiji

Journal of the Physical Society of Japan, 90(8), p.081003_1 - 081003_11, 2021/08

 Times Cited Count:1 Percentile:29.4(Physics, Multidisciplinary)

Journal Articles

Rabi-oscillation spectroscopy of the hyperfine structure of muonium atoms

Nishimura, Shoichiro*; Torii, Hiroyuki*; Fukao, Yoshinori*; Ito, Takashi; Iwasaki, Masahiko*; Kanda, Sotaro*; Kawagoe, Kiyotomo*; Kawall, D.*; Kawamura, Naritoshi*; Kurosawa, Noriyuki*; et al.

Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08

 Times Cited Count:7 Percentile:86.17(Optics)

Journal Articles

Droplet-entrainment phenomena affected by interfacial behavior of a high-speed gas jet into a liquid pool

Saito, Masafumi*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Kurihara, Akikazu; Takata, Takashi*; Ohshima, Hiroyuki

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 7 Pages, 2021/08

In order to provide the data for validation and improvement of the sodium-water reaction analysis code, a visualization experiment on liquid droplet entrainment in a high-pressure air jet submerged in a water pool was conducted. Diameter and velocity of entrained liquid droplets were successfully measured. The effect of a nozzle shape was elucidated.

Journal Articles

Barnett field, rotational Doppler effect, and Berry phase studied by nuclear quadrupole resonance with rotation

Chudo, Hiroyuki; Matsuo, Mamoru*; Maekawa, Sadamichi*; Saito, Eiji

Physical Review B, 103(17), p.174308_1 - 174308_10, 2021/05

 Times Cited Count:2 Percentile:19.54(Materials Science, Multidisciplinary)

Journal Articles

Effects of stress and plastic strain on hydrogen embrittlement fracture of a U-bent martensitic steel sheet

Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*

ISIJ International, 61(4), p.1322 - 1329, 2021/04

 Times Cited Count:2 Percentile:36.58(Metallurgy & Metallurgical Engineering)

Journal Articles

Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*

ISIJ International, 61(4), p.1170 - 1178, 2021/04

 Times Cited Count:1 Percentile:19.78(Metallurgy & Metallurgical Engineering)

Journal Articles

Incorporation of U, Pb and rare earth elements in calcite through crystallisation from amorphous calcium carbonate; Simple preparation of reference materials for microanalysis

Miyajima, Yusuke*; Saito, Ayaka*; Kagi, Hiroyuki*; Yokoyama, Tatsunori; Takahashi, Yoshio*; Hirata, Takafumi*

Geostandards and Geoanalytical Research, 45(1), p.189 - 205, 2021/03

 Times Cited Count:4 Percentile:33(Geochemistry & Geophysics)

Uncertainty for elemental and isotopic analyses of calcite by LA-ICP-MS is largely controlled by the homogeneity of the reference materials (RMs) used for normalization and validation. In order to produce calcite RMs with homogeneous elemental and isotopic compositions, we incorporated elements including U, Pb, and rare earth elements into calcite through heat- and pressure-induced crystallization from amorphous calcium carbonate that was precipitated from element-doped reagent solution. X-ray absorption spectra showed that U was present as U(VI) in the synthesized calcite, probably with a different local structure from that of aqueous uranyl ions. The uptake rate of U by our calcite was higher in comparison to synthetic calcite of previous studies. Variations of element mass fractions in the calcite were better than 12% 2RSD, mostly within 7%. The $$^{207}$$Pb/$$^{206}$$Pb ratio in the calcite showed $$<$$1% variations, while the $$^{238}$$U/$$^{206}$$Pb ratio showed 3-24% variations depending on element mass fractions. Using the synthetic calcite as primary RMs, we could date a natural calcite RM, WC-1, with analytical uncertainty as low as $$<$$3%. The method presented can be useful to produce calcite with controlled and homogeneous element mass fractions, and is a promising alternative to natural calcite RMs for U-Pb geochronology.

Journal Articles

Neutron diffraction study of hydrogen site occupancy in Fe$$_{0.95}$$Si$$_{0.05}$$ at 14.7 GPa and 800 K

Mori, Yuichiro*; Kagi, Hiroyuki*; Kakizawa, Sho*; Komatsu, Kazuki*; Shito, Chikara*; Iizuka, Riko*; Aoki, Katsutoshi*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; et al.

Journal of Mineralogical and Petrological Sciences, 116(6), p.309 - 313, 2021/00

 Times Cited Count:0 Percentile:0.02(Mineralogy)

The Earth's core is believed to contain some light elements because it is 10% less dense than pure Fe under the corresponding pressure and temperature conditions. Hydrogen, a promising candidate among light elements, has phase relations and physical properties that have been investigated mainly for the Fe-H system. This study specifically examined an Fe-Si-H system using in-situ neutron diffraction experiments to investigate the site occupancy of deuterium of hcp-Fez$$_{0.95}$$Si$$_{0.05}$$ hydride at 14.7 GPa and 800 K. Results of Rietveld refinement indicate hcp-Fe$$_{0.95}$$Si$$_{0.05}$$ hydride as having deuterium (D) occupancy of 0.24(2) exclusively at the interstitial octahedral site in the hcp lattice. The effect on the site occupancy of D by addition of 2.6 wt% Si into Fe (Fe$$_{0.95}$$Si$$_{0.05}$$) was negligible compared to results obtained from an earlier study of an Fe-D system (Machida et al., 2019).

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