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Neutron resonance fission neutron analysis for nondestructive fissile material assay

弘中 浩太; Lee, J.; 小泉 光生; 伊藤 史哲*; 堀 順一*; 寺田 和司*; 佐野 忠史*

Nuclear Instruments and Methods in Physics Research A, 1054, p.168467_1 - 168467_5, 2023/09

We propose neutron resonance fission neutron analysis (NRFNA), an active nondestructive assay (NDA) technique, to improve the capability to identify and quantify a small amount of fissile material in a sample. NRFNA uses pulsed neutrons to induce fission reactions in the sample. Fission neutrons are detected by a neutron-gamma pulse shape discrimination (PSD) scintillation detector with time-of-flight (TOF) technique. The obtained nuclide-specific resonance peaks in the neutron energy spectrum provide information to identify and quantify a fissile material in the sample. The possibility of using PSD for NRFNA was confirmed through a test experiment using a natural uranium sample. We successfully observed the resonance peaks from $$^{235}$$U(n,f) reaction and showed that NRFNA would be useful for measuring a small amount of fissile material in a sample.


New data processing method for nuclear material measurement using pulsed neutrons

米田 政夫; 藤 暢輔

Applied Radiation and Isotopes, 188, p.110391_1 - 110391_6, 2022/10

 被引用回数:0 パーセンタイル:0.01(Chemistry, Inorganic & Nuclear)

Active neutron methods using pulsed neutrons can measure nuclear materials with higher performance than passive methods. However, previous active neutron methods have not used the observed data effectively. In this study, we developed a new data processing method with higher performance than the conventional method by using time series data. This method is expected to improve the measurement performance through a significant reduction in measurement time and a sensitivity increase compared to the conventional method.


Experimental analysis on dynamics of liquid molecules adjacent to particles in nanofluids

橋本 俊輔*; 中島 健次; 菊地 龍弥*; 蒲沢 和也*; 柴田 薫; 山田 武*

Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11

 被引用回数:3 パーセンタイル:36.34(Chemistry, Physical)



Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Vu, TheDang; 宍戸 寛明*; 相澤 一也; 小嶋 健児*; 小山 富男*; 及川 健一; 原田 正英; 奥 隆之; 曽山 和彦; 宮嶋 茂之*; et al.

Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08

 被引用回数:0 パーセンタイル:0.02(Instruments & Instrumentation)

We found that the sizes of the Gd islands determined from the transmission image correlated strongly with those determined from the SEM image. We demonstrated the CB-KID could be used to identify (1) tiny voids in a thermally sprayed continuous Gd$$_2$$O$$_3$$ film in and (2) various mosaic morphologies and different eutectic microstructures in Wood's metal samples. The fact that the CB-KID system could be used to identify features of samples with a wide distribution of sizes and thicknesses is promising for real application of the device for imaging samples of interest to material scientists. Operating the CB-KID at higher temperatures appreciably improved the efficiency for simultaneously identifying the X and Y positions of hotspots. We also compared the detection efficiency with the PHITS simulations. We now plan to improve the detection efficiency by increasing the thickness of the $$^{10}$$B neutron conversion layer


Experimental characterization of high-energy component in extracted pulsed neutrons at the J-PARC spallation neutron source

原田 正英; 勅使河原 誠; 大井 元貴; 及川 健一; 高田 弘; 池田 裕二郎

Nuclear Instruments and Methods in Physics Research A, 1000, p.165252_1 - 165252_8, 2021/06

 被引用回数:1 パーセンタイル:24.48(Instruments & Instrumentation)

本研究では、箔放射化法を用いて、J-PARC核破砕中性子源からのパルス中性子ビームの高エネルギー成分を測定した。箔は、0.3MeVから79.4MeVまでのしきいエネルギーを持つAl, Au, Bi, Nb, Tmを用いた。実験はNOBORUで行われ、箔は減速材から13.4mの位置で照射された。照射実験への応用のために、高エネルギーの中性子スペクトルを変化させるB$$_{4}$$Cスリット, Pbフィルター、それらがない場合の3ケースでも反応率を測定した。JENDL-3.2評価済みファイルとJENDLドシメトリーファイルを用いたPHITSコードによる計算データと比較をした。計算値と実験値の比(C/E)を比較したところ、エネルギー依存性がみられ、しきいエネルギーが100MeVまで増えるにつれ、C/Eは減少することが分かった。すべてのC/Eは1.0$$pm$$0.2の範囲にあることを確認した。このことから、高エネルギーの中性子計算データは、NOBORUユーザーの実験データの分析に適切であることを示した。


A Two-dimensional scintillation neutron detector for TAKUMI diffractometer in J-PARC MLF

中村 龍也; 川崎 卓郎; 藤 健太郎; Harjo, S.; 坂佐井 馨; 相澤 一也

JPS Conference Proceedings (Internet), 33, p.011097_1 - 011097_6, 2021/03

J-PARC MLFのTAKUMI回折計のためのシンチレータ2次元中性子検出器を開発した。この検出器モジュールは有感面積32$$times$$32cmであり従来のSENJU型検出器の1.5倍の面積を有する。TAKUMIの中性子入射スペクトルに対応したシンチレータ厚さの最適化、新開発の高速低ノイズ回路の装填、ヘッド部の光収集効率の改良が施された。この検出器3台からなる1バンクを当該装置の後方散乱位置に配置され高ToF分解能、2次元での回折測定が可能となった。


Homogeneity of neutron transmission imaging over a large sensitive area with a four-channel superconducting detector

Vu, TheDang; 宍戸 寛明*; 小嶋 健児*; 小山 富男*; 及川 健一; 原田 正英; 宮嶋 茂之*; 奥 隆之; 曽山 和彦; 相澤 一也; et al.

Superconductor Science and Technology, 34(1), p.015010_1 - 015010_10, 2021/01

 被引用回数:3 パーセンタイル:36.64(Physics, Applied)

We demonstrated that a four-readout superconducting neutron imaging system shows good spatial heterogeneity and linearity using the delay-line method. We examined the precise pattern of a $$^{10}$$B-dot-array absorber and found the X-direction pitch (Px) = 250.7 um with a scatter of (Hx)= 5.4 um and the Y-direction pitch (Py)= 249.1 um with a scatter of (Hy)= 3.4 um while the $$^{10}$$B dot array was fully extended toward the X direction across the detector sensitive area. We consider that this demonstrates detection with good spatial homogeneity and conclude. The transmission-imaging system is suitable for use at pulsed neutron facilities. We also reported a clear transmission image of tiny screws and nuts, and ladybug (insect). We recognize that further efforts to improve the detection efficiency are necessary to make using the detector more practical.


Status and perspectives of the neutron time-of-flight facility n_TOF at CERN

Chiaveri, E.*; Aberle, O.*; Alcayne, V.*; 木村 敦; 他124名*

EPJ Web of Conferences, 239, p.17001_1 - 17001_8, 2020/09

 被引用回数:3 パーセンタイル:94.6

Since the start of its operation in 2001, the neutron time of-flight facility of CERN, n_TOF, has become one of the most forefront neutron facilities in the world for wide-energy spectrum neutron cross section measurements. Thanks to the combination of excellent neutron energy resolution and high instantaneous neutron flux available in the two experimental areas, the second of which has been constructed in 2014, n_TOF is providing a wealth of new data on neutron-induced reactions of interest for nuclear astrophysics, advanced nuclear technologies and medical applications. In this document the main characteristics of the n_TOF facility and their relevance for neutron studies in the different areas of research will be outlined. In addition, the future perspectives of the facility will be described including the upgrade of the spallation target, the setup of an imaging installation and the construction of a new irradiation area.


Kinetic inductance neutron detector operated at near critical temperature

Vu, TheDang; 西村 和真*; 宍戸 寛明*; 原田 正英; 及川 健一; 宮嶋 茂之*; 日高 睦夫*; 奥 隆之; 曽山 和彦; 相澤 一也; et al.

Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07

 被引用回数:0 パーセンタイル:0.01

Our CB-KID neutron imager detects high spatial resolution neutrons transmission images by using a delay-line technique. We found that the number of events was remarkably increased with increasing the detector temperature until close to the critical temperature Tc. We investigated the properties of CB-KID at near Tc. We observed systematic changes of neutron signals as a function of the detector temperature from 4 K to Tc. The simulations modeled the sequential physical processes for $$^{10}$$B(n,$$alpha$$)$$^{7}$$Li reactions and energy deposition by particles within CB-KID, including neutrons, $$^{4}$$He particles, $$^{7}$$Li particles, photon and electron transport.


Measurement of prompt neutron decay constant with spallation neutrons at Kyoto University Critical Assembly using linear combination method

方野 量太; 山中 正朗*; Pyeon, C. H.*

Journal of Nuclear Science and Technology, 57(2), p.169 - 176, 2020/02

 被引用回数:3 パーセンタイル:24.3(Nuclear Science & Technology)



Application of linear combination method to pulsed neutron source measurement at Kyoto University Critical Assembly

方野 量太; 山中 正朗*; Pyeon, C. H.*

Nuclear Science and Engineering, 193(12), p.1394 - 1402, 2019/12

 被引用回数:5 パーセンタイル:45.43(Nuclear Science & Technology)




麻生 智一; 達本 衡輝*; 大都 起一*; 川上 善彦*; 小守 慎司*; 武藤 秀生*; 高田 弘

JAEA-Technology 2019-013, 77 Pages, 2019/09


大強度陽子加速器施設(J-PARC)物質・生命科学実験施設において1MWの陽子ビームで駆動する核破砕中性子源では、水銀ターゲットで発生した高速中性子を冷中性子に冷却するために、液体水素(1.5MPa, 20K以下)を3基のモデレータに供給し、そこで発生する核発熱(3.8kW)を強制方式で冷却する低温水素システムを備えている。この低温水素システムでは、核発熱に伴う系内の圧力変動を低減するためにベローズ構造で圧力を吸収するアキュムレータを採用していることが特徴である。しかしながら、初期に使用したベローズで不具合が生じたため、高耐圧, 長寿命のアキュムレータが必要となった。厚肉プレートによる高耐圧性を有する溶接ベローズ(内ベローズ)の要素技術開発を行い、最適条件を見出すことができた。内ベローズの試作機を製作し、2MPaの圧力印加を繰り返す耐久試験により、設計寿命(1万回以上)を満たすことを確認した。また、その製作法による内ベローズを導入したアキュムレータの組立時、溶接歪等によって内ベローズの機能性や寿命に影響しないように、水平・垂直度を0.1$$^{circ}$$以内に抑えた。改良したアキュムレータは既に約25,000時間(繰り返し伸縮約16,000回(運転中40mm伸縮の設計寿命は50万回))の運転を実現できており、2019年1月現在、500kWビーム出力で運転中である。2018年7月には932kWビーム入射した運転を行い、アキュムレータの圧力変動抑制機能が設計どおりの性能を有することを確認し、今後の高出力において安定運転ができる見通しを得た。


Visualization of phase distribution in lead-bismuth eutectic during one-dimensional solidification process

伊藤 大介*; 佐藤 博隆*; 齊藤 泰司*; Parker, J. D.*; 篠原 武尚; 甲斐 哲也

Journal of Visualization, 22(5), p.889 - 895, 2019/06

 被引用回数:1 パーセンタイル:8.23(Computer Science, Interdisciplinary Applications)

Solidification process of lead-bismuth eutectic (LBE) is one of the key phenomena to prevent flow channel blockage accident in an LBE-cooled accelerator-driven system. However, the solidification of liquid metal cannot be observed optically and it is difficult to detect noninvasively. In this study, the one-dimensional solidification process of the LBE was visualized by pulsed neutron transmission imaging. Neutrons have higher transmittivity to the LBE than X-ray and neutron transmission spectrum of the LBE sample can be obtained by pulsed neutron imaging technique. The solid and liquid phases of the LBE were identified during the solidification process by the presence or absence of Bragg edge in the measured neutron transmission spectrum, and the transient behavior of the solid-liquid interface could be visualized. In addition, the characteristic spatial distribution of the crystalline structure was found in Bragg-edge transmission image after the solidification.


Area ratio method via linear combination of the neutron counts in pulsed neutron experiment

方野 量太

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05



Estimation method of prompt neutron decay constant reducing higher order mode effect by linear combination

方野 量太

Nuclear Science and Engineering, 193(4), p.431 - 439, 2019/04

 被引用回数:6 パーセンタイル:60.63(Nuclear Science & Technology)




池田 裕二郎; 清水 裕彦*

レーザー研究, 46(11), p.641 - 646, 2018/11



Experimental validation of the brightness distribution on the surfaces of coupled and decoupled moderators composed of 99.8% parahydrogen at the J-PARC pulsed spallation neutron source

原田 正英; 勅使河原 誠; 大井 元貴; Klinkby, E.*; Zanini, L.*; Batkov, K.*; 及川 健一; 藤 暢輔; 木村 敦; 池田 裕二郎

Nuclear Instruments and Methods in Physics Research A, 903, p.38 - 45, 2018/09

 被引用回数:8 パーセンタイル:66.51(Instruments & Instrumentation)

At the J-PARC pulsed spallation neutron source, liquid hydrogen moderators composed of 99.8% parahydrogen associated with light-water premoderator have been providing high intensity cold and thermal neutron beams. In the design stage, simulations have shown not only high total neutron intensity in the coupled moderator but also a local neutron-brightness increase at the edges. The edge-effect-brightness increase is also exploited in the design of the European Spallation Source (ESS) moderators, which are based on 99.8% parahydrogen, but thin (thickness: 3 cm) to enhance the neutron brightness. In this study, the spatial distribution of the neutron brightness at the surface of the coupled moderator in the J-PARC pulsed spallation neutron source was directly measured with the pinhole geometry to validate the calculated edge-brightness enhancement. The brightness distribution at the moderator surface was clearly observed as predicted by a Monte Carlo simulation, proving the validity of the simulation tools used in the design-optimization process of the J-PARC and ESS moderator.


Study on neutron beam pulse width dependence in the nuclear fuel measurement by the neutron resonance transmission analysis

北谷 文人; 土屋 晴文; 藤 暢輔; 堀 順一*; 佐野 忠史*; 高橋 佳之*; 中島 健*

KURRI Progress Report 2017, P. 99, 2018/08

As a non-destructive analytical technique for nuclear material in the field of nuclear security and nuclear nonproliferation, a neutron resonance transmission analysis (NRTA) attracts attention of researchers. It is important to downsize a NRTA system when it is deployed at various facilities. For this aim, we have developed a compact NRTA system which utilizes a D-T neutron generator. Its pulse width of 10$$mu$$s is much longer than that of a large electron beam accelerator. It is necessary to understand the influence of pulse widths on the NRTA measurement. Therefore, we conducted the experiments of the simulated nuclear fuel pin samples to evaluate how the NRTA measurement is influenced by the pulse width of neutron beam. Experiments were performed in Kyoto University. The simulated fuel pellet sample was made from metallic powders of Ag (around 1%) and Al (around 99%). The energy of the irradiation neutron is determined by a Time of Flight technique. We used three pulse widths of the neutron beam of 0.1, 1 and 4 $$mu$$s. A resonance dip of $$^{108}$$Ag at 5.19 eV is observed in the all spectra. And the dip of the TOF spectrum shifts towards low energy, with pulse width changed to a longer one. In this work, we confirmed that neutron pulse width affected the NRTA measurement of the fuel pin sample. On the basis of this work, we will be able to quantify the effects of long-pulse width in a resonance analysis.


ダイナミクス解析装置DNAの実用化; 背面反射結晶アナライザー型高エネルギー分解能中性子分光器の系譜

柴田 薫

波紋, 28(1), p.26 - 28, 2018/02



Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

勅使河原 誠; 池田 裕二郎; 大井 元貴; 原田 正英; 高田 弘; 柿白 賢紀*; 野口 学*; 島田 翼*; 清板 恭一*; 村島 大亮*; et al.

Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)


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