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Endo, Akira
Annals of the ICRP, 52(4), p.5 - 7, 2024/12
In its Publication 155, International Commission on Radiological Protection (ICRP) has developed data on the Specific Absorbed Fraction (SAF) for reference males and females at ages of newborn, 1 year, 5 years, 10 years, and 15 years. The SAF represents the fraction of energy emitted within a source region which is absorbed in a target region per mass of the target region and is essential for calculating absorbed doses in organs or tissues for internal exposure. By combining the data of Publication 155 with the SAF data for reference adult males and females already published as Publication 133, an SAF dataset for the calculation of age-dependent dose coefficients for members of the public for environmental intakes of radionuclides has been completed. This, together with revised biokinetic models and nuclear decay data, means that the key building blocks for calculating new dose coefficients are in place. The outcome will soon be available in a series of ICRP Publications of Dose Coefficients for Intakes of Radionuclides by Members of the Public.
Arai, Yoichi; Watanabe, So; Watanabe, Masayuki; Arai, Tsuyoshi*; Katsuki, Kenta*; Agou, Tomohiro*; Fujikawa, Hisaharu*; Takeda, Keisuke*; Fukumoto, Hiroki*; Hoshina, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research B, 554, p.165448_1 - 165448_10, 2024/09
Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)Shikaze, Yoshiaki
Journal of Nuclear Science and Technology, 61(7), p.894 - 910, 2024/07
Times Cited Count:2 Percentile:57.39(Nuclear Science & Technology)Among the radioactive nuclides inside the nuclear reactor buildings emitted by the Fukushima Daiichi nuclear reactor accident, high-energy beta-ray sources, such as strontium-90 and yttrium-90, generate bremsstrahlung photons in the building materials, comprising the wall, floor, and interior structure. Therefore, evaluating the radiation dose of the bremsstrahlung to the workers in the nuclear reactor building is crucial for radiation protection. The precision of the evaluation calculation of the bremsstrahlung dose was investigated by comparing the Particle and Heavy Ion Transport code System (PHITS) and the GEometry ANd Tracking (GEANT4) simulation code results. In the calculation, behind various shielding plates (lead, copper, aluminum, glass, and polyethylene, with thicknesses ranging from 1.0 to 40 mm), the water cylinder was set as the evaluated material, the absorbed dose and the deposited energy spectrum by the bremsstrahlung photons were obtained, and the characteristics and differences for both simulation codes were investigated. In the comparison results of the deposited energy spectrum, the spectral shapes have consistent trends. In the energy range below several tens of keV, a peak is seen in the PHITS spectrum for the lead shielding material. In comparing the absorbed dose under various conditions of the shielding plate for generating bremsstrahlung photons, most results for both codes correlate within an 10% difference for 2.280 MeV beta-ray sources and an
20% difference for 0.5459 MeV beta-ray sources, except for
30% for 20 mm thick lead. Although there were differences in some cases, the evaluation results of the two simulation codes were concluded to correlate well with the above precision.
Collaborative Laboratories for Advanced Decommissioning Science; Shinshu University*
JAEA-Review 2023-053, 87 Pages, 2024/05
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of environmental mitigation technology with novel water purification agents" conducted from FY2020 to FY2022. The present study aims to develop a reusable adsorbent for strontium ions with high adsorption property to contribute to the improvement of the treatment process of radioactive contaminated water generated by the Great East Japan Earthquake. As a result, reusable adsorbent materials showing excellent Sr adsorption performances were developed. The current adsorbent materials for strontium are extremely expensive and single use, so the storage and disposal of massive generation of waste have become a major problem.
Soler, J. M.*; Kekl
inen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*;
ha, J.*; Havlov
, V.*; Trpko
ov
, D.*; et al.
Nuclear Technology, 209(11), p.1765 - 1784, 2023/11
Times Cited Count:3 Percentile:73.09(Nuclear Science & Technology)Takahatake, Yoko; Watanabe, So; Arai, Tsuyoshi*; Sato, Takahiro*; Shibata, Atsuhiro
Applied Radiation and Isotopes, 196, p.110783_1 - 110783_5, 2023/06
Times Cited Count:1 Percentile:34.39(Chemistry, Inorganic & Nuclear)Collaborative Laboratories for Advanced Decommissioning Science; Shinshu University*
JAEA-Review 2022-067, 98 Pages, 2023/03
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of environmental mitigation technology with novel water purification agents" conducted in FY2021. The present study aims to develop a reusable adsorbent for strontium ions through joint research between Japan and the United Kingdom, and to reduce the amount of used adsorbent generated through the decontamination process. This fiscal year, the preparation method of materials was improved based on the results obtained in the first year of the project. Moreover, various metal salts were added as additives to see the influence on the yield and adsorption performance. Structural analyses were conducted by observing the resulting materials with SEM, and theoretical analyses were performed by combining ...
Suzuki, Tomoya*; Otsubo, Ukyo*; Ogata, Takeshi*; Shiwaku, Hideaki; Kobayashi, Toru; Yaita, Tsuyoshi; Matsuoka, Mitsuaki*; Murayama, Norihiro*; Narita, Hirokazu*
Separation and Purification Technology, 308, p.122943_1 - 122943_7, 2023/03
Times Cited Count:3 Percentile:19.28(Engineering, Chemical)HNO leaching is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) often remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO
solutions is essential to promote efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO
solutions was investigated using four N-donor-type adsorbents functionalized with amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), or bis-picolylamine (R-BPA). R-Amine, R-IDA, and R-Py selectively adsorbed Pd(II) over Ag(I), Cu(II), Ni(II), and Fe(III) from HNO
solutions (0.3-7 M), but R-Amine exhibited a lower Pd adsorption efficiency. In contrast,
90% of Pd(II), Ag(I), and Cu(II) were adsorbed by R-BPA over the entire range of HNO
concentrations. Structural analyses of the adsorbed metal ions using Fourier transform infrared spectroscopy and extended X-ray absorption fine structure spectroscopy revealed the separation mechanisms of the N-donor-type adsorbents. Pd(II) adsorption on R-IDA, R-Py, and R-BPA occurred via Pd(II) coordination of the functional groups (iminodiacetic acid, pyridine, and bis-picolylamine, respectively), whereas that on R-Amine occurred via anion exchange of NO
with [Pd(NO
)
]
. The coordinative adsorption mechanisms resulted in the higher Pd(II) adsorption behaviors of R-IDA, R-Py, and R-BPA. HCl (5.0 M) and thiourea (0.1 M) eluents desorbed 83% of Pd(II) from R-IDA and 95% from R-Py, respectively. R-Py was the most effective Pd(II) adsorbent based on adsorption selectivity and desorption efficiency.
Collaborative Laboratories for Advanced Decommissioning Science; Shinshu University*
JAEA-Review 2021-051, 81 Pages, 2022/01
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of environmental mitigation technology with novel water purification agents" conducted in FY2020. The present study aims to develop a reusable adsorbent for strontium ions through joint research between Japan and the United Kingdom, and to reduce the amount of used adsorbent generated through the decontamination process. The basic strategy of this research is to produce adsorbents and examine their Sr adsorption performance at Shinshu University. The structural analyses of the adsorbents are conducted by the Institute for Molecular Science (IMS) and the UK teams.
Hidaka, Akihide
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.341 - 356, 2021/10
Toigawa, Tomohiro; Tsubata, Yasuhiro; Kai, Takeshi; Furuta, Takuya; Kumagai, Yuta; Matsumura, Tatsuro
Solvent Extraction and Ion Exchange, 39(1), p.74 - 89, 2021/00
Times Cited Count:2 Percentile:8.03(Chemistry, Multidisciplinary)Absorbed-dose estimation is essential for evaluation of the radiation feasibility of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha ray depends upon the emulsion structure, and that from beta and gamma ray depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process.
Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko; Horita, Takuma; Yomogida, Takumi; Kitatsuji, Yoshihiro
Analytical Chemistry, 92(4), p.3276 - 3284, 2020/02
Times Cited Count:6 Percentile:28.07(Chemistry, Analytical)The long-term safety assessment of spent Cs adsorbents produced during the decontamination of radiocesium-containing water at the Fukushima Daiichi Nuclear Power Plant requires one to estimate their Cs content prior to final disposal.
Cs is usually quantified by inductively coupled plasma mass spectrometry (ICP-MS), which necessitates the elution of Cs from Cs adsorbents. However, this approach suffers from the high radiation dose from
Cs. To address this challenge, we herein employed laser ablation ICP-MS for direct quantitation of
Cs in Cs adsorbents and used a model Cs adsorbent prepared by immersion of a commercially available Cs adsorbent into radiocesium-containing liquid waste to verify the developed technique. The use of the
Cs/
Cs ratio and
Cs radioactivity obtained by gamma spectrometry achieved simple and precise quantitation of
Cs and the resulting
Cs activity of 0.36 Bq agreed well with that in the original radiocesium-containing liquid waste.
Kofuji, Hirohide; Watanabe, So; Takeuchi, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.61 - 65, 2018/11
Takada, Hiroshi
Plasma and Fusion Research (Internet), 13(Sp.1), p.2505013_1 - 2505013_8, 2018/03
The pulsed spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC) has been supplying users with high intensity and sharp pulse cold neutrons using the moderators with following distinctive features; (1) 100% para-hydrogen for increasing pulse peak intensity with decreasing pulse tail, (2) cylindrical shape with 14 cm diam.12 cm long for providing high intensity neutrons to wide neutron extraction angles of 50.8
, (3) neutron absorber made from Ag-In-Cd alloy to make pulse width narrower and pulse tails lower. Actually, it was measured at a low power operation that high neutron intensity of 4.5
10
n/cm
/s/sr could be emitted from the coupled moderator surface for 1-MW operation, and a superior resolution of
d/d = 0.035% was achieved at a beamline (BL8) with a poisoned moderator, where d is the d-spacing of reflection. Towards the goal to achieve the target operation at 1-MW for 5000 h in a year, technical developments to mitigate cavitation damages on the target vessel with injecting gas micro-bubbles into mercury target and design improvement of target vessel structure to reducing welds and bolt connections as much as possible are under way.
Azami, Kazuhiro*; Otagaki, Takahiro*; Ishida, Mutsushi; Sanada, Yukihisa
Landscape and Ecological Engineering, 14(1), p.3 - 15, 2018/01
Times Cited Count:2 Percentile:10.60(Biodiversity Conservation)Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.
Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.
Hidaka, Akihide; Yokoyama, Hiroya
Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2017 (AWC 2017) (USB Flash Drive), p.29 - 42, 2017/09
no abstracts in English
Takeuchi, Masayuki; Sano, Yuichi; Watanabe, So; Nakahara, Masaumi; Aihara, Haruka; Kofuji, Hirohide; Koizumi, Tsutomu; Mizuno, Tomoyasu
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04
Awual, M. R.; Miyazaki, Yuji; Taguchi, Tomitsugu; Shiwaku, Hideaki; Yaita, Tsuyoshi
Chemical Engineering Journal, 291, p.128 - 137, 2016/05
Times Cited Count:243 Percentile:99.25(Engineering, Environmental)Awual, M. R.; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu
Scientific Reports (Internet), 6, p.19937_1 - 19937_10, 2016/01
Times Cited Count:198 Percentile:97.40(Multidisciplinary Sciences)