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Rapid analysis of $$^{90}$$Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometry

小荒井 一真; 松枝 誠; 青木 譲; 柳澤 華代*; 寺島 元基; 藤原 健壮; 木野 康志*; 岡 壽崇; 高橋 温*; 鈴木 敏彦*; et al.

Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08

 被引用回数:0 パーセンタイル:0.02(Chemistry, Analytical)



Radioactivity and radionuclides in deciduous teeth formed before the Fukushima-Daiichi Nuclear Power Plant accident

高橋 温*; 千葉 美麗*; 棚原 朗*; 相田 潤*; 清水 良央*; 鈴木 敏彦*; 村上 忍*; 小荒井 一真; 小野 拓実*; 岡 壽崇; et al.

Scientific Reports (Internet), 11(1), p.10355_1 - 10355_11, 2021/05

 被引用回数:1 パーセンタイル:65.97(Multidisciplinary Sciences)

The Fukushima-Daiichi Nuclear Power Plant (FNPP) accident released substantial amounts of radionuclides into the environment. We collected 4,957 deciduous teeth, from children living in Fukushima and reference prefectures. Radioactivity was detected in most of the teeth examined and was attributed to the presence of natural radionuclides, including $$^{40}$$K and daughter nuclides in $$^{238}$$U and $$^{232}$$Th series. Additionally, artificial radionuclides, $$^{90}$$Sr and $$^{137}$$Cs, were detected in the teeth obtained from children from Fukushima and the reference prefectures. However, these radionuclides were not believed to have originated from the FNPP accident. Because the teeth examined in the present study were formed before the FNPP accident occurred, the aforementioned findings may serve as important control data for future studies regarding the radioactivity of teeth formed after the FNPP accident.


Speciation of cesium in tree tissues and its implication for uptake and translocation of radiocesium in tree bodies

田中 万也; 金指 努*; 竹中 千里*; 高橋 嘉夫*

Science of the Total Environment, 755(Part 2), p.142598_1 - 142598_8, 2021/02

 被引用回数:3 パーセンタイル:83.41(Environmental Sciences)



A Sensitive method for Sr-90 analysis by accelerator mass spectrometry

笹 公和*; 本多 真紀; 細谷 青児*; 高橋 努*; 高野 健太*; 落合 悠太*; 坂口 綾*; 栗田 沙緒里*; 佐藤 志彦; 末木 啓介*

Journal of Nuclear Science and Technology, 58(1), p.72 - 79, 2021/01

 被引用回数:1 パーセンタイル:39.17(Nuclear Science & Technology)

Strontium-90 ($$^{90}$$Sr) is one of the most important fission products due to the potential health risks of its uptake and retention in the human body. Conventional analysis techniques involve beta-counting, which requires ingrowth of $$^{90}$$Y over a period of two weeks or more. Accelerator mass spectrometry (AMS) has the potential to shorten the analysis time while offering a lower limit of detection than beta-counting. Here, Sr in samples was recovered as SrF$$_{2}$$ to provide sufficient negative ions in the caesium-sputtering ion source. In the sample preparation step, 95-98% of Sr was recovered and 99-100% of Zr removed by ion-exchange separation. Sr recovery was $$sim$$30% in the precipitation process, and this can be improved. The recovered $$^{90}$$Sr was mixed with PbF$$_{2}$$ at an SrF$$_{2}$$:PbF$$_{2}$$ weight ratio of 4:1. A maximum 500 nA beam current of Sr$$_{3}$$ ions was obtained from SrF$$_{2}$$ samples. A five-anode gas ionization detector was used to avoid isobaric interference from $$^{90}$$Zr. The $$^{90}$$Sr/Sr atomic ratio background of $$sim$$6 $$times$$ 10$$^{-13}$$ (equivalent to $$sim$$3 mBq $$^{90}$$Sr) was comparable with that achieved at other AMS facilities. Good linearity $$^{90}$$Sr/Sr atomic ratios was obtained from 1.75 $$times$$ 10$$^{-10}$$ to 3.38 $$times$$ 10$$^{-9}$$. Suitable techniques for sample preparation and measurement were thus achieved for $$^{90}$$Sr analysis by AMS.


External exposure dose estimation by electron spin resonance technique for wild Japanese macaque captured in Fukushima Prefecture

岡 壽崇; 高橋 温*; 小荒井 一真; 光安 優典*; 木野 康志*; 関根 勉*; 清水 良央*; 千葉 美麗*; 鈴木 敏彦*; 小坂 健*; et al.

Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06

 被引用回数:1 パーセンタイル:39.17(Nuclear Science & Technology)



Sorption behavior of selenide on montmorillonite

杉浦 佑樹; 戸村 努*; 石寺 孝充; 土井 玲祐; Francisco, P. C. M.; 塩飽 秀啓; 小林 徹; 松村 大樹; 高橋 嘉夫*; 舘 幸男

Journal of Radioanalytical and Nuclear Chemistry, 324(2), p.615 - 622, 2020/05

 被引用回数:1 パーセンタイル:0.01(Chemistry, Analytical)

Batch sorption experiments were performed to investigate the sorption mechanism of Se on montmorillonite under reducing conditions in deep geological environments. Based on Eh-pH diagrams and ultraviolet-visible spectra, Se was dissolved as selenide (Se(-II)) anions under the experimental conditions. The distribution coefficients ($$K_{rm d}$$; m$$^{3}$$ kg$$^{-1}$$) of Se(-II) indicated ionic strength independence and slight pH dependence. The $$K_{rm d}$$ values of Se(-II) were higher than those of Se(IV), which also exists as an anionic species. X-ray absorption near edge spectroscopy showed that the oxidation state of Se-sorbed on montmorillonite was zero even though selenide remained in the solution. These results suggest that Se(-II) was oxidized and precipitated on the montmorillonite surface. Therefore, it is implied that a redox reaction on the montmorillonite surface contributed to high $$K_{rm d}$$ values for Se(-II).


Pre- and post-accident $$^{14}$$C activities in tree rings near the Fukushima Dai-ichi Nuclear Power Plant

松中 哲也*; 笹 公和*; 高橋 努*; 松村 万寿美*; 佐藤 志彦; Shen, H.*; 末木 啓介*; 松崎 浩之*

Radiocarbon, 61(6), p.1633 - 1642, 2019/12

 被引用回数:0 パーセンタイル:0.01(Geochemistry & Geophysics)

Areas affected by routine radiocarbon ($$^{14}$$C) discharges from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) and accidental releases in March 2011 were investigated by analysis of cores from Japanese cypress and cedar trees growing at sites 9 and 24 km northwest of the plant. $$^{14}$$C concentrations in tree rings from 2008-2014 (before and after the accident) were determined by accelerator mass spectrometry, with $$^{14}$$C activities in the range 231-256 Bq kg$$^{-1}$$ C. Activities during the period 2012-2014, after FDNPP shutdown, represent background levels, while the significantly higher levels recorded during 2008-2010, before the accident, indicate uptake of $$^{14}$$C from routine FDNPP operations. The mean excess $$^{14}$$C activity for the pre-accident period at the sites 9 and 24 km northwest of the plant were 21 and 12 Bq kg$$^{-1}$$ C, respectively, indicating that the area of influence during routine FDNPP operations extended at least 24 km northwest. The mean excess tree-ring $$^{14}$$C activities in 2011 were 10 and 5.8 Bq kg$$^{-1}$$ C at 9 and 24 km northwest, respectively, documenting possible impact of the FDNPP accident on $$^{14}$$C levels in trees.



太田 祐貴*; 末木 啓介*; 笹 公和*; 高橋 努*; 松中 哲也*; 松村 万寿美*; 戸崎 裕貴*; 本多 真紀*; 細谷 青児*; 高野 健太*; et al.

JAEA-Conf 2018-002, p.99 - 102, 2019/02

福島第一原子力発電所事故により放出された放射性核種に長寿命の$$^{36}$$Cl(半減期: 30.1万年)がある。$$^{36}$$Clは放射性廃棄物の処理の際に土壌中における高い移動能と相まって重要な核種である。しかし、土壌中では無機塩素(Clinorg)が有機塩素(Clorg)に変換・保持されることで、その移動の機構は不明である。本研究では、汚染地域の無機$$^{36}$$Clの深度分布を得ることで$$^{36}$$Clの動態を検討し、事故による$$^{36}$$Cl汚染の程度を検討した。また、5cm表土に含まれる$$^{36}$$Clについても検討した。2017年における深度分布では、$$^{36}$$Cl濃度は表層で最も高くなり、深度とともに緩やかに減少した。一方で、$$^{36}$$Cl/Clはほぼ一定(平均値: 3.24$$pm$$0.55 ($$times$$10$$^{-12}$$))の値を示した。事故前の$$^{36}$$Cl/Clと比べると$$^{36}$$Cl/Clの増加を示し、事故由来の$$^{36}$$Clは土壌3.6g/cm$$^{2}$$(=5cm深)より深く移動していることが分かった。


Radiocarbon variations in tree rings since 1960 near the Tokai nuclear facility, Japan

松中 哲也*; 笹 公和*; 高橋 努*; 細谷 青児*; 松村 万寿美*; 佐藤 志彦; Shen, H.*; 末木 啓介*

Nuclear Instruments and Methods in Physics Research B, 439, p.64 - 69, 2019/01

 被引用回数:2 パーセンタイル:42.44(Instruments & Instrumentation)



Quantum paramagnet near spin-state transition

富安 啓輔*; 伊藤 菜緒子*; 岡崎 竜二*; 高橋 佑生*; 小野寺 貢*; 岩佐 和晃*; 野島 勉*; 青山 拓也*; 大串 研也*; 石川 喜久*; et al.

Advanced Quantum Technologies (Internet), 1(3), p.1800057_1 - 1800057_7, 2018/12



Application of the transient pulse method to measure clay permeability

加藤 昌治*; 奈良 禎太*; 岡崎 勇樹*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

Materials Transactions, 59(9), p.1427 - 1432, 2018/09

 被引用回数:3 パーセンタイル:28.45(Materials Science, Multidisciplinary)



Evaluation of thermal strain induced in components of Nb$$_{3}$$Sn strand during cooling

諏訪 友音*; 辺見 努*; 齊藤 徹*; 高橋 良和*; 小泉 徳潔*; Luzin, V.*; 鈴木 裕士; Harjo, S.

IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04

 被引用回数:0 パーセンタイル:0(Engineering, Electrical & Electronic)

Nb$$_{3}$$Sn strands, whose properties are very sensitive to stress/strain, are utilized for ITER cable-in-conduit conductor (CICC) of the central solenoids. The Nb$$_{3}$$Sn strands experience temperature range of $$sim$$1000 K from the temperature of the heat treatment with the initiation of the Nb$$_{3}$$Sn reaction to the operation temperature of $$sim$$4 K. Due to this large temperature range, large thermal strain is induced in the Nb$$_{3}$$Sn filaments due to the differences between the coefficients of thermal expansion and Young's moduli of the components of the strand. Therefore, it is considered that initial performance of the CICC is influenced by the thermal strain on the Nb$$_{3}$$Sn, and it is important to evaluate the strain state of the Nb$$_{3}$$Sn strand at low temperature. In this study, the thermal strain of the components of free Nb$$_{3}$$Sn strand was measured by neutron diffraction and stress/strain state was assessed from room temperature to low temperature. As the results of diffraction measurements, it was found that 0.111 % and 0.209 % compressive strain were generated in Nb$$_{3}$$Sn filaments at 300 and 10 K, respectively.


Permeability of granite including macro-fracture naturally filled with fine-grained minerals

奈良 禎太*; 加藤 昌治*; 二里 竜平*; 河野 勝宣*; 佐藤 稔紀; 福田 大祐*; 佐藤 努*; 高橋 学*

Pure and Applied Geophysics, 175(3), p.917 - 927, 2018/03

 被引用回数:7 パーセンタイル:55.03(Geochemistry & Geophysics)




加藤 昌治*; 奈良 禎太*; 岡崎 勇樹*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

材料, 67(3), p.318 - 323, 2018/03




松中 哲也*; 笹 公和*; 高橋 努*; 細谷 青児*; 松村 万寿美*; 末木 啓介*; 佐藤 志彦

第19回AMSシンポジウム・2016年度「樹木年輪」研究会共同開催シンポジウム報告集, p.76 - 79, 2017/06

原子力施設の稼働に伴い放出する$$^{14}$$C放出量を松の木の年輪に含まれる$$^{14}$$Cを測定することで評価した。結果、(1)東海原子力施設周辺における1967-2010年単年輪内の$$^{14}$$C濃度は、北半球バックグラウンドに比べ2.6-70Bq kg$$^{-1}$$C高かった。(2)単年輪内の余剰$$^{14}$$C濃度は、2つの原子力発電所からの$$^{14}$$C放出量変動の影響を受けて、稼働開始時期と終了時期におよそ応答して増加傾向と減少傾向を示した。(3)再処理施設からの$$^{14}$$C放出量が比較的多かった3つの時期(1980年, 1985年, 1992年付近)に余剰$$^{14}$$C濃度の増大が認められた。(4)主として東海原子力施設に由来すると考えられる単年輪内余剰$$^{14}$$Cは、食物摂取による実効線量に換算すると最大で3.9$$mu$$Sv yr$$^{-1}$$程度であった。



加藤 昌治*; 奈良 禎太*; 福田 大祐*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

材料, 65(7), p.489 - 495, 2016/07



Non-destructive examination of jacket sections for ITER central solenoid conductors

高橋 良和; 諏訪 友音; 名原 啓博; 尾関 秀将; 辺見 努; 布谷 嘉彦; 礒野 高明; 松井 邦浩; 河野 勝己; 押切 雅幸; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200904_1 - 4200904_4, 2015/06

 被引用回数:0 パーセンタイル:0(Engineering, Electrical & Electronic)

原子力機構はITER中心ソレノイド(CS)コイル用導体の調達を担当し、製作したCS導体をコイル製作担当の米国に送付することになっている。CSコイルは高さ約12m、外径約4mで、6個のモジュールを積み重ねた構造を有する。導体の単長は最大910mであり、通電電流値は13Tの磁場中において40kAである。導体はケーブル・イン・コンジット型と呼ばれるもので、576本のNb$$_{3}$$Sn素線と288本の銅素線で構成される撚線を、矩形の中に円形の穴がある高マンガン鋼(JK2LB)製ジャケットに挿入し、ジャケットを圧縮成型したものである。圧縮成型される前のジャケットは、外寸法51.3mm、穴の直径35.3mm、単長7m、重さ約90kgである。このジャケットは、出荷前に非破壊検査により、最大許容サイズの欠陥がないことを確認する必要がある。内及び外表面の欠陥は、渦電流探傷(ECT)法 で、内部の欠陥は、超音波探傷(UT)法で行われる。UTにおいて、矩形の中に円形の穴がある形状であるので、超音波の入射の方向を工夫する必要があった。表面のECT及び内部のUTについて、その技術と検査実績を報告する。


Behavior of Nb$$_{3}$$Sn cable assembled with conduit for ITER central solenoid

名原 啓博; 諏訪 友音; 高橋 良和; 辺見 努; 梶谷 秀樹; 尾関 秀将; 櫻井 武尊; 井口 将秀; 布谷 嘉彦; 礒野 高明; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200305_1 - 4200305_5, 2015/06

 被引用回数:0 パーセンタイル:0(Engineering, Electrical & Electronic)

JAEA procures all superconductors for central solenoid (CS) in the ITER project. The cable is inserted into a conduit and compacted with it. During the insertion, the number of the rotation at the point ($$N_{p}$$) of the TF cable increased linearly to 50 against the inserted cable length ($$l_{i}$$). At first, $$N_{p}$$ of the CS cable also increased linearly by $$l_{i}$$ of 150 m. However, the increasing rate declined and the $$N_{p}$$ became constant to 30 at 600 m. During the compaction, the number of the rotation at the tail ($$N_{t}$$) of the CS cable increased linearly to 69 against the compacted cable length ($$l_{c}$$). It is important to measure not only $$N_{p}$$ but also $$N_{t}$$ because the rotation affects the twist pitch of the cable ($$l_{p}$$). After manufacturing the CS conductor, an X-ray transmission imaging made clear the $$l_{p}$$ along the whole length of the conductor for the first time. The $$l_{p}$$ peaked at the point; thus, a conductor sample should be taken there to investigate the effect of the $$l_{p}$$ elongation on the conductor performance.


Optimization of heat treatment of Japanese Nb$$_3$$Sn conductors for toroidal field coils in ITER

名原 啓博; 辺見 努; 梶谷 秀樹; 尾関 秀将; 諏訪 友音; 井口 将秀; 布谷 嘉彦; 礒野 高明; 松井 邦浩; 小泉 徳潔; et al.

IEEE Transactions on Applied Superconductivity, 24(3), p.6000605_1 - 6000605_5, 2014/06



Cabling technology of Nb$$_3$$Sn conductor for ITER central solenoid

高橋 良和; 名原 啓博; 尾関 秀将; 辺見 努; 布谷 嘉彦; 礒野 高明; 松井 邦浩; 河野 勝己; 押切 雅幸; 宇野 康弘; et al.

IEEE Transactions on Applied Superconductivity, 24(3), p.4802404_1 - 4802404_4, 2014/06

 被引用回数:20 パーセンタイル:73.53(Engineering, Electrical & Electronic)


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