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高崎 浩司; 安宗 貴志; 山口 祐加子; 橋本 周; 前田 宏治; 加藤 正人
Journal of Nuclear Science and Technology, 60(11), p.1437 - 1446, 2023/11
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)空気力学的放射能中央径(AMAD)は内部被ばくの評価に必要な情報である。2017年6月6日に日本原子力研究開発機構の大洗サイトのプルトニウム取扱施設において、核燃料物質を収納した貯蔵容器の調査作業中に事故的な汚染が発生し、5名の作業者がプルトニウムを含む放射性物質を吸入した。線量評価のために、いくつかのスミアろ紙と空気サンプリングフィルタをイメージングプレートで測定し、硝酸プルトニウムと二酸化プルトニウムの2つのケースの最小AMADを保守的に推定した。AMADの指定の結果、スミアろ紙の極端に大きな粒子を除いても、塗抹紙からの硝酸プルトニウムの最小AMADは4.3-11.3
m、二酸化プルトニウムのそれは5.6-14.1mであった。また、空気サンプリングフィルタからの硝酸プルトニウムの最小AMADは3.0mで、二酸化プルトニウムは3.9mであった。
土屋 晴文; 藤 暢輔; 大図 章; 古高 和禎; 北谷 文人; 前田 亮; 米田 政夫
Journal of Nuclear Science and Technology, 60(11), p.1301 - 1312, 2023/11
被引用回数：1 パーセンタイル：72.91(Nuclear Science & Technology)An integrated active neutron non-destructive analysis (NDA) system, Active-N, was developed to gain knowledge of active neutron NDA techniques that are applicable to measurements of nuclear materials in highly radioactive nuclear fuels. Active-N, equipped with a D-T neutron generator, combines three complementary active neutron NDA techniques: Differential Die-away Analysis (DDA), Prompt Gamma-ray Analysis (PGA), and Neutron Resonance Transmission Analysis (NRTA). In this paper, we provide an overview of Active-N and then demonstrate that the compact NRTA system in Active-N can quantify nuclear materials. Monte Carlo simulations were conducted to determine the design of the compact NRTA system including a moderator, flight tubes, and a detector shield. To investigate how accurately the compact NRTA system determines areal densities in a sample, measurements were performed with a Pu pellet-type sample as well as metallic plate samples of In and Ag. The experimental areal densities of 
Pu, 
In and 
Ag were consistent with those calculated for the individual nuclei. These results show that it is feasible to develop a compact NRTA system capable of determining the contents of nuclear materials in nuclear fuels. This research was implemented under the subsidy for nuclear security promotion of MEXT.
前田 亮; 瀬川 麻里子; 藤 暢輔; 遠藤 駿典; 中村 詔司; 木村 敦
Journal of Radioanalytical and Nuclear Chemistry, 332(8), p.2995 - 2999, 2023/08
被引用回数：0 パーセンタイル：0.01(Chemistry, Analytical)The accuracy of the prompt 
-ray analysis is known to degrade for the samples containing neutron-scattering materials, such as hydrogen, depending on its content. Recently, we discovered that the density of the scattering materials also affects the accuracy. In this paper, we developed a correction method for the effect of the sample densities. The developed correction method is straightforward and applicable to samples with unknown densities. The simulation and experiments verified the performance of the correction method. The results confirmed that the correction method could reduce the uncertainty due to sample density from 47% to approximately 1%.
-ray analysis木下 哲一*; 能任 琢真*; 中島 均*; 小迫 和明*; 加藤 雄大*; 黒岩 洋一*; 倉部 美彩子*; 佐々木 勇気*; 鳥居 和敬*; 前田 亮; et al.
Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.479 - 486, 2023/02
There are some different chemical and physical forms of water molecules in concretes. Especially, bound water is difficult to determine. In the present work, we determined free + adsorbed water and bound water contained in aggregates and cement pastes, which are component of concretes, by means of conventional gravimetric analysis and prompt -ray analysis (PGA), respectively, in order to evaluate a total water content in concretes. In the PGA, background reduction was attempted by using the time-of-flight (TOF) signal. In addition, the degree of contribution to analytical values by scattered neutrons by samples was evaluated because water would adsorb on the surface of instruments inside the irradiation chamber for the PGA. Contents of the free + adsorbed water and bound water in some geochemical references determined in the present work were compared with the nominal values to confirm the precision. Each water content in aggregates collected from different quarries and cement pastes with different water-to-cement ratios were analyzed. A total water content in young concrete was evaluated on the basis of the analytical values.
Ta遠藤 駿典; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之; Rovira Leveroni, G.; 藤 暢輔; 瀬川 麻里子; 前田 亮
Nuclear Science and Engineering, 18 Pages, 2023/00
被引用回数：1 パーセンタイル：72.91(Nuclear Science & Technology)The neutron transmission ratio and capture yield for Ta were measured in J-PARC MLF ANNRI to improve the accuracy of resonance parameters. The total cross section was determined from the transmission ratio in the energy range from 0.2 to 150 eV. The capture cross section was obtained from the capture yield using the pulse height weighting technique (PHWT) in the energy range from thermal to 150 eV. The obtained transmission ratio and capture cross-section were fitted by the resonance analysis code, REFIT, and the resonance parameters were determined below 150 eV. It was also discussed the correlations caused by fitting based on statistical uncertainty and correlations for systematic uncertainty based on sample thickness in the transmission measurements.
-ray analysis前田 亮; 瀬川 麻里子; 藤 暢輔; 遠藤 駿典; 中村 詔司; 木村 敦
Scientific Reports (Internet), 12(1), p.6287_1 - 6287_8, 2022/06
被引用回数：2 パーセンタイル：31.9(Multidisciplinary Sciences)A high-accuracy analytical method is broadly required to obtain reliable research results. Thus, prompt -ray analysis (PGA), one of the most accurate non-destructive analytical methods, has been employed in various fields. However, the measurement accuracy of PGA is also known to degrade in hydrogenous samples. The degradation is caused by variation in the measurement sensitivity (counts per milligram) following the change in neutron energy due to scattering with hydrogen nucleus. Number of scatterings is well known to depend on the hydrogen content in a sample. However, considering multiple scatterings, hydrogen density, which has not been taken into account as yet, may also lead to the accuracy degradation. In this research, the effect of the hydrogen density in PGA is investigated by evaluating the measurement sensitivity of samples with the same hydrogen content and different densities. The results showed that the measurement sensitivity varies by more than 30% depending on the hydrogen density even at the same hydrogen content. The variation is a particularly serious problem for PGA requiring a few percent accuracy in most cases. Additionally, although the variation is apparently observed in hydrogenous samples, the similar phenomenon can occur in other nuclides with a large scattering cross section; it may affect nuclear cross-section measurements using neutrons in such fields as astrophysics and nuclear energy.
遠藤 駿典; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之; Rovira Leveroni, G.; 寺田 和司*; 明午 伸一郎; 藤 暢輔; 瀬川 麻里子; et al.
Journal of Nuclear Science and Technology, 59(3), p.318 - 333, 2022/03
被引用回数：5 パーセンタイル：65.59(Nuclear Science & Technology)In order to improve the accuracy of the cross-section and the resonance parameters of 
Nb, neutron capture and total cross-sections were measured using the J-PARC MLF ANNRI. The thermal-neutron capture cross-section was deduced as 0.97
0.12 b. The resonance parameters of 11 resonances below 400 eV were determined from obtained capture cross-sections and transmission ratios by using the resonance analysis code, REFIT.
藤 暢輔; 大図 章; 土屋 晴文; 古高 和禎; 北谷 文人; 米田 政夫; 前田 亮; 小泉 光生
Proceedings of INMM & ESARDA Joint Virtual Annual Meeting (Internet), 8 Pages, 2021/08
Since neutrons have exceptional ability to penetrate high-density materials and can induce fission, they are used in non-destructive analysis such as, Differential Die-Away Analysis (DDA), Prompt Gamma-ray Analysis (PGA) and Neutron Resonance Transmission Analysis (NRTA). The different analytical methods give us complementary information, which are particularly useful for the quantification of Special Nuclear Materials in highly radioactive nuclear materials, including spent fuel. The Japan Atomic Energy Agency (JAEA) and the Joint Research Centre (JRC) of the European Commission are collaborating to develop an active neutron NDA system for nuclear non-proliferation and nuclear security. In the second phase of the project, an integrated active neutron NDA system: Active-N which enables the simultaneous measurements of DDA, PGA and NRTA has been developed. The DDA detects fission neutrons, and it can determine small amounts of the fissile mass. PGA is utilized for the quantification of neutron absorber and particularly useful for the detection of explosives. NRTA can be used to quantify almost all medium and high-Z elements and considered as one of the most accurate NDA. In this presentation, we will provide an overview of Active-N and report the recent experimental results. This research was implemented under the subsidy for nuclear security promotion of MEXT: Ministry of Education, Culture, Sports, Science and Technology.
Pd and 
Tc藤 暢輔; 瀬川 麻里子; 前田 亮; 常山 正幸*; 木村 敦; 中村 詔司; 遠藤 駿典; 海老原 充*
Analytical Chemistry, 93(28), p.9771 - 9777, 2021/07
被引用回数：4 パーセンタイル：24.69(Chemistry, Analytical)Considering the expanding demand for nuclear waste management of the spent nuclear fuel materials in near future, a non-destructive analytical scheme applicable to the most difficult-to-measure nuclide of Pd, which emits no decay gamma-rays and whose half-life is too long to be decayed out during a human lifetime, was designed. The scheme consists of a sophisticated instrument capable of the detection of gamma-rays by Ge detectors coupled with time-of-flight measurement of neutrons and a high-intensity pulsed neutron beam, and can simultaneously perform TOF-coupled prompt gamma-ray analysis (TOF-PGA) as well as PGA and NRCA. An analytical capability was evaluated by applying to simulated samples of the Tc-platinum group metals (Tc-PGMs) obtained by the group partitioning process of spent nuclear fuels, which contain not only Pd but also Tc and another difficult-to-measure fission product. It was confirmed that, although PGA and NRCA could accurately analyze both nuclides in individual single substances, only TOF-PGA can analyze Pd as well as Tc in the Tc-PGMs simulated sample. The TOF-PGA measurement technique can be widely used for the non-destructive analysis of Pd and Tc in nuclear wastes.
土川 雄介; 阿部 雄太; 大石 佑治*; 甲斐 哲也; 藤 暢輔; 瀬川 麻里子; 前田 亮; 木村 敦; 中村 詔司; 原田 正英; et al.
JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03
福島原子力発電所の解体作業では、溶融した燃料棒に含まれるホウ素分布を事前に把握することが重要である。溶融燃料棒の模擬試験体を用意し、ホウ素やホウ化物の含有量を調査する研究が行われてきた。本研究では、その一環として中性子を用いたホウ素並びにホウ化物分布の測定技術開発を行った。ホウ素の中性子吸収に伴う即発ガンマ線を測定し、ホウ素量や二次元分布を測定した。また、n(B,
)反応における478keV線は、ホウ素の化合状態により、線ピークの幅が変化することが知られている。このことを用い、特に溶融燃料棒周辺に存在することが予測されているZrBやFeBといったホウ化物の識別可能性について調査した。測定はJ-PARC/MLFのANNRI, NOBORU, RADENにて行った。これらの解析結果について報告する。
At using an -scintillation-camera system and thin-layer chromatography瀬川 麻里子; 西中 一朗*; 藤 暢輔; 前田 亮
Journal of Radioanalytical and Nuclear Chemistry, 326(1), p.773 - 778, 2020/10
被引用回数：1 パーセンタイル：12.16(Chemistry, Analytical)At is a candidate nuclide for alpha-targeted therapy. In order to use At as a pharmaceutical, the radioactivity and chemical forms of generated At are the most fundamental specifications that need to be analyzed prior to its medical use. However, previous methods of separately measuring the radioactivity and chemical forms are not adaptable to the medical use of At because they cause a severe loss of At and do not analyze all the chemical forms of At. Therefore, a new analytical method for both the radioactivity and chemical forms of generated At is urgently needed. Accordingly, in this study, we developed an experimental system optimized to simultaneously analyze both the radioactivity and chemical forms of a At solution to significantly shorten the analysis time; we experimentally verified the accuracy and capabilities of this system at the Japan Atomic Energy Agency. The experiments confirmed that the present system could analyze the radioactivity and all the chemical forms of At with an uncertainty of approximately 5% in the region higher than 150 Bq and that it was 200 times more sensitive than the conventional method using an imaging technique with an X-ray imaging plate. As a result, a new method for analyzing the radioactivity and chemical forms of At was successfully established and this method will meet the demands for alpha-targeted therapy using At. This method will contribute to promoting the stable supply of the medical use of At in the near future.
大図 章; 前田 亮; 米田 政夫; 藤 暢輔
Proceedings of 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2019), Vol.1, p.101 - 104, 2020/08
In the fields of safeguards, nuclear non-proliferation, and nuclear security, non-destructive analysis (NDA) techniques useful for highly radioactive nuclear materials (NMs) are not established yet because there are so many technical difficulties to measure the amount of the highly radioactive NMs. A novel NDA system with a pulsed neutron source as the method for determining the composition of mixed NMs has been developing in the Japan Atomic Energy Agency. In the NDA system, a differential die-away analysis (DDA) technique is used to quantify the amount of fissile materials. The detection limit of fissile materials in DDA system is determined by the signal to noise ratio in fast neutron counting. A method to reduce the noise signal by using neutron absorber (B
C rubber) sheets mounted on the inner entire surface in the sample cavity is proposed. The effect of the sheets on the reduction of noise signal in the fast neutron counting was investigated in both experimental test and simulation. The experimental results show that it is possible to detect a nuclear fissile material (
Pu) of as low as 1 mg in a vial bottle when the absorber sheets with a thickness of 3 mm is used. This paper also presents comparison between experimental data and simulation results.
中野 政尚; 細見 健二; 西村 周作; 松原 菜摘; 大倉 毅史; 倉持 彰彦; 川崎 将亜; 竹内 絵里奈; 藤井 裕*; 神野 職*; et al.
保健物理(インターネット), 55(2), p.102 - 109, 2020/06
2011年3月の東京電力福島第一原子力発電所事故以降、茨城県の環境放射線モニタリング結果の一部に上昇が観測された。技術的観点からモニタリングデータの変動等について意見交換する場として、「福島第一原発事故による環境影響検討会」を設置し、4つの原子力事業所からモニタリングデータを収集し、変動傾向, 
Cs/
Cs放射能比等を検討した。本報告では線量率と、降下じん, 表土, カレイ・ヒラメ, 海底土中Csの検討結果について紹介する。また、検討会における課題解決についても紹介する。
NpRovira, G.*; 片渕 竜也*; 登坂 健一*; 松浦 翔太*; 寺田 和司*; 岩本 修; 木村 敦; 中村 詔司; 岩本 信之; 瀬川 麻里子; et al.
Journal of Nuclear Science and Technology, 57(1), p.24 - 39, 2020/01
被引用回数：10 パーセンタイル：79.13(Nuclear Science & Technology)The neutron capture cross-section of Np has been measured in the neutron energy region of 10 meV to 500 eV. A neutron time-of-flight method was employed using the NaI(Tl) spectrometer in the ANNRI beam-line at the Japanese Proton Accelerator Re-search Complex (J-PARC). The experimental capture yield was derived using the pulse-height weighting technique and an energy dependent cross-section was obtained relative to the incident neutron spectrum derived from a 
B(n, )
Li reaction yield. The absolute cross-section was determined by normalizing the results to JENDL-4.0 cross-section data at the first resonance of Np. The thermal cross-section was measured to be 177.6 3.8 b. The resolved resonance region was analyzed with the REFIT code.
大図 章; 前田 亮; 米田 政夫; 藤 暢輔
Proceedings of 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2018) (Internet), 4 Pages, 2019/10
A Differential Die-away Analysis (DDA) system using a compact pulsed neutron (DT: 14 MeV) generator has been successfully developed for nuclear non-proliferation and nuclear security in the Japan Atomic Energy Agency. The DDA system employing the fast neutron direct interrogation method is designed to quantify fissile materials in samples which have different volume from a vial bottle (4 cc) to pail container (20 liter). It has been demonstrated experimentally that the DDA system is capable of quantifying a nuclear fissile material (Pu-239) less than 10 mg in a vial bottle. The performance of the DDA system with a large measurement sample such as a MOX can container (2 liter) was evaluated through the Monte Carlo simulation studies. The simulation results show that the Pu-239 mass of around 10 mg even in the MOX can container can be detected. The results of the simulation study are discussed and compared to those of the experimental test.
岡 眞; 前田 沙織*; Liu, Y.-R.*
International Journal of Modern Physics; Conference Series (Internet), 49, p.1960004_1 - 1960004_8, 2019/07
被引用回数：6 パーセンタイル：94.54(Astronomy & Astrophysics)本論文は、チャームバリオン, 
や
と核子
の束縛状態について、ポテンシャルクォーク模型による短距離力とメソン交換による長距離力の組み合わせによって生じる共鳴状態の発見を論じている。複素スケーリング法を用いた解析で、-と
-の閾値のすぐ下に幅の狭い共鳴が存在することを示した。
前田 亮; 古高 和禎; 呉田 昌俊; 大図 章; 米田 政夫; 藤 暢輔
Journal of Nuclear Science and Technology, 56(7), p.617 - 628, 2019/07
被引用回数：3 パーセンタイル：31.89(Nuclear Science & Technology)In order to measure the amount of nuclear materials in the fuel debris produced in the Fukushima Daiichi Nuclear Power Plant accident, we have designed a measurement system based on a Fast Neutron Direct Interrogation (FNDI) method. In particular, we have developed a fast response detector bank for fast neutron measurements by Monte Carlo simulations. The new bank has more than an order of magnitude faster response compared to the standard ones. We have also simulated the nondestructive measurements of the nuclear materials in homogeneously mixed fuel debris with various matrices which contain Stainless Steel (JIS SUS304), concrete, and various control-rod (CR) contents in the designed system. The results show that at least some types of the fissile materials in the debris can be measured by using the designed system.
藤 暢輔; 大図 章; 土屋 晴文; 古高 和禎; 北谷 文人; 米田 政夫; 前田 亮; 小泉 光生
Proceedings of INMM 60th Annual Meeting (Internet), 7 Pages, 2019/07
Nuclear material accountancy plays a key role in nuclear safeguards and security. The collaboration between the Japan Atomic Energy Agency (JAEA) and the Joint Research Centre (JRC) of the European Commission aims to develop an active neutron NDA system for Special Nuclear Materials (SNM) and Minor Actinides (MA) in highly radioactive nuclear materials. Several active neutron NDA techniques, namely Differential Die-Away Analysis (DDA), Prompt Gamma-ray Analysis (PGA), Neutron Resonance Capture Analysis (NRCA), Neutron Resonance Transmission Analysis (NRTA) and Delayed Gamma-ray Analysis (DGA) have been developed. The different methods can provide complementary information. In the first phase of the project, we developed a combined NDA system, which enables the simultaneous measurements of DDA and PGA. The DDA technique can determine very small amounts of the fissile mass. PGA is valuable for the measurement of light elements. In the second phase, we will continue to conduct additional research to improve the methodology and develop a new integrated NDA system which can use for NRTA as well as DDA and PGA. In this presentation, we will provide an overview of the project and report the recent results, especially the design of new integrated NDA system. This research was implemented under the subsidiary for nuclear security promotion of MEXT.
高崎 浩司; 安宗 貴志; 橋本 周; 前田 宏治; 加藤 正人; 吉澤 道夫; 百瀬 琢麿
JAEA-Review 2019-003, 48 Pages, 2019/03
JAEA-Review-2019-003.pdf:3.81MB
平成29年6月6日に大洗研究開発センター燃料研究棟の管理区域内において、貯蔵容器の点検等作業中、貯蔵容器内にある核燃料物質が入った容器を封入した樹脂製の袋が破裂した。室内で作業をしていた作業員5名は半面マスクを着用していたが、5名全員が飛散したPu等のダストで汚染され、体内摂取による内部被ばくが生じた。国際放射線防護委員会は作業者による放射性核種の吸入摂取について、空気力学的放射能中央径(AMAD)の1mと5mの実効線量係数を示しており、内部被ばく線量の評価において、放射性粒子のAMADは重要な情報である。事象発生後に採取した室内のスミヤ試料14枚とPuダストモニタのサンプリングろ紙1枚について、イメージングプレートで測定し、画像解析により室内に飛散したPu等の粒子のAMADを評価した。評価の結果、スミヤ試料からは硝酸Pu塩と仮定した場合のAMADは4.3
11m以上、酸化Puと仮定した場合のAMADは5.614m以上と評価された。また、Puダストモニタの集塵ろ紙については、硝酸Pu塩とした場合のAMADは3.0m以上、酸化Puとした場合は3.9m以上と評価された。
大図 章; 前田 亮; 米田 政夫; 藤 暢輔; 小泉 光生; 瀬谷 道夫
Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 4 Pages, 2018/11
A Differential Die-away Analysis (DDA) system using a compact pulsed neutron (14 MeV) generator has been newly developed for non-nuclear proliferation and nuclear security in the Japan Atomic Energy Agency (JAEA). The DDA system was designed to be able to detect a nuclear fissile material (Pu-239) of as low as 10 mg and to handle samples of a different volume: a vial bottle (20 mL), a pail container (20 L), through a Monte Carlo simulation. In the DDA system, the Fast Neutron Direct Interrogation (FNDI) technique, which utilizes fast neutrons for interrogation, was applied to measure the amount of fissile mass contained in the sample. The fundamental performance of the DDA system was investigated in the demonstration experiment. The simulation results show that the Pu-239 masses of less than 10 mg can be detected in the DDA system. The results of the experiment are discussed and compared with those of the simulation.
