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Journal Articles

Integrated radiation air dose rate maps over the 80 km radius of the Fukushima Daiichi Nuclear Power Plant and the entire Fukushima Prefecture during 2011-2022

Sakuma, Kazuyuki; Kurikami, Hiroshi; Wainwright, Haruko*; Tanimori, Soichiro*; Nagao, Fumiya; Ochi, Kotaro; Sanada, Yukihisa; Saito, Kimiaki

Journal of Environmental Radioactivity, 280, p.107554_1 - 107554_11, 2024/12

 Times Cited Count:2 Percentile:53.16(Environmental Sciences)

In this study, we created the integrated radiation air dose rate maps in the Fukushima region during 2011-2022 using multiple types of surveys such as air-borne, car-borne and walk surveys as well as fixed-location measurements. We applied the Bayesian geostatistical method developed by Wainwright et al. (2017, 2019) to the 80 km radius of the Fukushima Daiichi Nuclear Power Plant and the whole of Fukushima Prefecture while considering the history of the lifting of the evacuation zone in Fukushima. The integrated maps fixed the bias to underestimate air dose rates in forest areas, and successfully created more reproducible integrated maps with a wider area and time series than the previous studies. It is highly expected that the results of this study will be used to evaluate detailed exposure doses to the general public.

Journal Articles

A Systematic approach for the adequacy analysis of a set of experimental databases; Application in the framework of the ATRIUM activity

Baccou, J.*; Glantz, T.*; Ghione, A.*; Sargentini, L.*; Fillion, P.*; Damblin, G.*; Sueur, R.*; Iooss, B.*; Fang, J.*; Liu, J.*; et al.

Nuclear Engineering and Design, 421, p.113035_1 - 113035_16, 2024/05

 Times Cited Count:6 Percentile:96.49(Nuclear Science & Technology)

Journal Articles

Microbiome analysis of the restricted bacteria in radioactive element-containing water at the Fukushima Daiichi Nuclear Power Station

Warashina, Tomoro*; Sato, Asako*; Hinai, Hiroshi; Shaikhutdinov, N.*; Shagimardanova, E.*; Mori, Hiroshi*; Tamaki, Satoshi*; Saito, Motofumi*; Sanada, Yukihisa; Sasaki, Yoshito; et al.

Applied and Environmental Microbiology, 90(4), p.e02113-23_1 - e02113-23_23, 2024/04

 Times Cited Count:0 Percentile:0.00(Biotechnology & Applied Microbiology)

Journal Articles

Polarized neutron diffraction study on UPt$$_{2}$$Si$$_{2}$$

Kon, Fusako*; Tabata, Chihiro; Saito, Hiraku*; Nakajima, Taro*; Hidaka, Hiroyuki*; Yanagisawa, Tatsuya*; Amitsuka, Hiroshi*

Journal of the Physical Society of Japan, 93(4), p.044701_1 - 044701_11, 2024/04

 Times Cited Count:0 Percentile:0.00(Physics, Multidisciplinary)

Journal Articles

Latent ion tracks were finally observed in diamond

Amekura, Hiroshi*; Chettah, A.*; Narumi, Kazumasa*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Leino, A. A.*; Djurabekova, F.*; Nordlund, K.*; et al.

Nature Communications (Internet), 15, p.1786_1 - 1786_10, 2024/02

 Times Cited Count:2 Percentile:57.35(Multidisciplinary Sciences)

Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2-9 MeV C$$_{60}$$ fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which $$pi$$-bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS).

Journal Articles

Investigation on the management of uranium-containing wastes in view of humanities and social sciences

Yasuda, Hiroshi*; Saito, Tatsuo; Fumoto, Hiromichi*; Sugawara, Shinetsu*; Tsuchida, Shoji*; Kasai, Atsushi*; Furuta, Sadaaki*

Hoken Butsuri (Internet), 58(3), p.120 - 134, 2023/11

This paper is a summary of the activity report of the specialized study group of the Japan Health Physics Society on handling of naturally occurring radioactive wastes from humanities and social sciences perspective. To ensure the reliability of the long-term assessment, this special committee first reviews options for disposal of uranium waste depending on its concentration, especially those adopted or considered in Japan and overseas (U.S.A., U.K.) for uranium concentrations exceeding a sufficiently small amount of uranium (an average of 1 Bq/g of the sum of $$^{234}$$U, $$^{235}$$U, and $$^{238}$$U).

Journal Articles

Measurements of gas-liquid two-phase flow dynamics using high-speed neutron imaging

Ito, Daisuke*; Odaira, Naoya*; Ito, Kei*; Saito, Yasushi*; Kurita, Keisuke; Iikura, Hiroshi

Journal of Physics; Conference Series, 2605, p.012024_1 - 012024_6, 2023/10

Gas-liquid two-phase flow appears in many heat-exchanging devices. To understand the phenomena in such devices, the two-phase flow dynamics should be clarified. In this study, high-speed neutron imaging is applied to the measurements of two-phase flow dynamics, and the accuracy of the void fraction measurement is investigated.

Journal Articles

Introduction to Neutron Radiography Facilities at the Japan Research Reactor-3

Kurita, Keisuke; Iikura, Hiroshi; Tsuchikawa, Yusuke; Kai, Tetsuya; Shinohara, Takenao; Odaira, Naoya*; Ito, Daisuke*; Saito, Yasushi*; Matsubayashi, Masahito

Journal of Physics; Conference Series, 2605, p.012005_1 - 012005_6, 2023/10

The Japan Research Ractor-3 (JRR-3) is operation resumed on February 26, 2021, and the shared use was also restarted in July, 2021. With the resumption of JRR-3 operation, two imaging facilities called TNRF and CNRF have also resumed their utilization. In this presentation, we report the details of these two neutron facilities.

Journal Articles

Development of tracer particles for thermal hydraulic experiment by neutron imaging

Saito, Yasushi*; Ito, Daisuke*; Odaira, Naoya*; Kurita, Keisuke; Iikura, Hiroshi

Journal of Physics; Conference Series, 2605, p.012028_1 - 012028_6, 2023/10

To observe flow velocity distributions by Neutron Imaging, suitable tracer is necessary. The requirements are its density, its visibility, and its wettability (if applied to liquid metal). Gold cadmium tracers have been developed for the Pb-Bi two-phase flow, however, the visibility have not been verified depending on the particle size and the measurement system. As the candidates of tracer particles, Ag, Cd, Au-Cd, and Ag-Cd have been tested by varying its compositions and its diameters. Results show enough visibility if the particles size is larger than 1mm. In addition, Cd tracer particles were applied to the fluidized bed, where the bed materials are metallic particle made of stainless steel, with 1mm diameter. The diameter of Cd trace is about 1.5 mm. From the neutron imaging, the visibility of the tracers is enough to measure the velocity distributions in the fluidized bed.

Journal Articles

Impact of the ground-state 4${it f}$ symmetry for anisotropic ${it cf}$ hybridization in the heavy-fermion superconductor CeNi$$_{2}$$Ge$$_{2}$$

Fujiwara, Hidenori*; Nakatani, Yasuhiro*; Aratani, Hidekazu*; Kanai-Nakata, Yuina*; Yamagami, Kohei*; Hamamoto, Satoru*; Kiss, Takayuki*; Yamasaki, Atsushi*; Higashiya, Atsushi*; Imada, Shin*; et al.

Physical Review B, 108(16), p.165121_1 - 165121_10, 2023/10

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

JAEA Reports

Decommissioning state of Plutonium Fuel Fabrication Facility; Dismantling the glove box W-9 and equipment interior, and a part of tunnel F1

Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.

JAEA-Technology 2022-039, 117 Pages, 2023/06

JAEA-Technology-2022-039.pdf:11.96MB

Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process.

Journal Articles

Visualization of gas-liquid interfacial behavior in a narrow channel using high-speed neutron imaging

Ito, Daisuke*; Odaira, Naoya*; Ito, Kei*; Saito, Yasushi*; Kurita, Keisuke; Iikura, Hiroshi

Konsoryu, 37(1), p.73 - 78, 2023/03

Gas-liquid two-phase flow is a very complicated flow phenomenon that involves the interaction between gas and liquid phases. Recently, an accurate simulation technique of two-phase flow has been developed. However, the validation of the simulated results is insufficient due to less experimental data. It is especially difficult to measure interfacial behavior with significant spatiotemporal fluctuation. To understand such phenomena, measurement methods with high spatial and temporal resolutions are required. Neutron imaging is a powerful tool for two-phase flow visualization. In this study, two-phase flow in the narrow rectangular channel was visualized by high-speed neutron imaging.

Journal Articles

Difference in expansion and dehydration behaviors between NH$$_4$$- and K-montmorillonite

Kawakita, Ryohei; Saito, Akito*; Sakuma, Hiroshi*; Anraku, Sohtaro; Kikuchi, Ryosuke*; Otake, Tsubasa*; Sato, Tsutomu*

Applied Clay Science, 231, p.106722_1 - 106722_7, 2023/01

 Times Cited Count:2 Percentile:17.27(Chemistry, Physical)

Journal Articles

Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

Iwase, Akihiro*; Fukuda, Kengo*; Saito, Yuichi*; Okamoto, Yoshihiro; Semboshi, Satoshi*; Amekura, Hiroshi*; Matsui, Toshiyuki*

Journal of Applied Physics, 132(16), p.163902_1 - 163902_10, 2022/10

 Times Cited Count:0 Percentile:0.00(Physics, Applied)

Amorphous SiO$$_{2}$$ samples were implanted with 380 keV Fe ions at room temperature. After implantation, some of the samples were irradiated with 16 MeV Au ions. magnetic properties were investigated using a SQUID magnetometer, and the morphology of the Fe-implanted SiO$$_{2}$$ samples was examined using transmission electron microscopy and X-ray absorption spectroscopy (EXAFS and XANES), which showed that the size of Fe nanoparticles was increasing The size of Fe nanoparticles increased with increasing Fe implantation amount; some of the Fe nanoparticles consisted of Fe oxides, and the valence and structure of Fe atoms became closer to that of metallic $$alpha$$-Fe with increasing Fe injection amount. The magnetization-field curve of the sample implanted with a small amount of Fe was reproduced by Langevin's equation, suggesting that the Fe nanoparticles behave in a superparamagnetic manner. In addition, when a large amount of Fe was implanted, the magnetization-magnetic field curve shows a ferromagnetic state. These magnetic property results are consistent with the X-ray absorption results. Subsequent 16 MeV Au irradiation crushed the Fe nanoparticles, resulting in a decrease in magnetization.

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

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

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:7 Percentile:65.84(Chemistry, Analytical)

Journal Articles

Sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions onto sedimentary rock in the presence of gamma-irradiated humic acid

Zhao, Q.*; Saito, Takeshi*; Miyakawa, Kazuya; Sasamoto, Hiroshi; Kobayashi, Taishi*; Sasaki, Takayuki*

Journal of Hazardous Materials, 428, p.128211_1 - 128211_10, 2022/04

 Times Cited Count:7 Percentile:45.72(Engineering, Environmental)

The influence of humic acid and its radiological degradation on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ by sedimentary rock was investigated to understand the sorption process of metal ions and humic substances. Aldrich humic acid (HA) solution was irradiated with different doses of gamma irradiation using a Co-60 gamma-ray source prior to the contact between the metal ions and the solid sorbent. The HA molecule decomposed to smaller molecules with a lower complexation affinity. Batch sorption experiments were performed to evaluate the effect of gamma-irradiated HA on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions. The addition of non-irradiated HA weakened the sorption of Eu because of the lower sorption of the neutral or negatively charged Eu-HA complexes compared with free Eu ions. The sorption of monovalent Cs ions was barely affected by the presence of HA and its gamma irradiation. The concentration ratio of HA complexed species and non-complexed species in the solid and liquid phases was evaluated by sequential filtration and chemical equilibrium calculations. The ratios supported the minimal contribution of HA to Cs sorption. However, the concentration ratio for Eu$$^{3+}$$ in the liquid phase was high, indicating that the complexing ability of HA to Eu$$^{3+}$$ was higher than that of HA to Cs$$^{+}$$ ions. Therefore, the sorption of free Eu$$^{3+}$$ would predominate with the gamma irradiation dose applied to the HA solution under a radiation field near the HLW package.

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.

Advances in X-Ray Chemical Analysis, Japan, 53, p.223 - 229, 2022/03

no abstracts in English

Journal Articles

Current status of the environmental monitoring database on the accident at Fukushima Daiichi Nuclear Power Plant

Seki, Akiyuki; Saito, Kimiaki; Takemiya, Hiroshi

Journal of Radiological Protection, 41(3), p.S89 - S98, 2021/09

 Times Cited Count:6 Percentile:55.57(Environmental Sciences)

An enormous amount of environmental monitoring data has been acquired by various organizations for evaluation and implementation of countermeasure to mitigate the effects of the accident at the Fukushima Daiichi Nuclear Power Plant. We established procedures to collect these data, convert them into a unified format, classify them according to categories, and make the data accessible on a web-based database system. The database system enabled us to spatially and temporally compare large volumes of monitoring data. By using the database functions, characteristics of some representative data in the database were clarified.

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