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論文

Technique of neutron resonance transmission analysis for active neutron NDA

土屋 晴文; 小泉 光生; 北谷 文人; 呉田 昌俊; 原田 秀郎; 瀬谷 道夫; Heyse, J.*; Kopecky, S.*; Mondelaers, W.*; Paradela, C.*; et al.

Proceedings of 37th ESARDA Annual Meeting (Internet), p.846 - 851, 2015/08

中性子の共鳴反応を利用した分析手法に、中性子共鳴透過分析法(NRTA)がある。本技術を活用してMA混入核燃料に含まれているウランやプルトニウムを検出・定量するアクティブ中性子非破壊分析法を開発している。さらに、本手法をMA混入核燃料のみならず、高放射線場の中にあるさまざまな物質の定量に適用することを目指している。これまで粒子状の燃料デブリへの適用を目的として、われわれが開発してきた中性子共鳴濃度分析法(NRD)で得た知見を本技術開発に活かす。NRTAにより、透過中性子スペクトルの解析を通じてウランやプルトニウムを同定・定量する。本発表では、NRTAの基礎を紹介するとともに、開発するアクティブ中性子を用いた非破壊測定手法の中でのNRTAの役割を説明する。その上で、NRDの開発で得た知見を紹介するとともに、本技術開発の中でのNRTAの今後の検討項目について議論する。

論文

Techniques of neutron resonance capture analysis and prompt $$gamma$$-ray analysis for active neutron NDA

小泉 光生; 土屋 晴文; 北谷 文人; 呉田 昌俊; 瀬谷 道夫; 原田 秀郎; Heyse, J.*; Kopecky, S.*; Mondelaers, W.*; Paradela, C.*; et al.

Proceedings of 37th ESARDA Annual Meeting (Internet), p.852 - 858, 2015/08

Active NDA techniques will draw out more information on the sample objects, in comparison with passive NDA techniques. Elementary particles (such as photons and neutrons) are used to induce nuclear reactions in the sample objects. The materials in the objects are deduced from the measured particles coming out of them. A new development program of active neutron NDA technologies has been started for detection/measurement of nuclear materials using a pulsed neutron source for nuclear security and nuclear non-proliferation; this project includes the basic technological development of NRTA, NRCA/PGA, neutron differential die-away (DDA) and a Delayed Gamma-ray (DG) technique. A system of active neutron NDA has been proposed. In this presentation, we review the methods and techniques on NRCA and PGA, which will be utilized for identifying materials in the objects in active neutron NDA.

論文

NRD demonstration experiments at GELINA

Paradela, C.*; Alaerts, G.*; Becker, B.*; 原田 秀郎; Heyse, J.*; 北谷 文人; 小泉 光生; Kopecky, S.*; Mondelaers, W.*; Moens, A.*; et al.

EUR-27507-EN, 16 Pages, 2015/04

Neutron Resonance Densitometry (NRD), a non-destructive analysis method, is presented. The method has been developed to quantify special nuclear material (SNM) in debris of melted fuel that will be produced during the decommissioning of the Fukushima Daiichi Nuclear Power Plants. The method is based on Neutron Resonance Transmission Analysis (NRTA) and Neutron Resonance Capture Analysis (NRCA). The quantification of SNM relies on the NRTA results. The basic principles of NRD, which are based on well-established methodologies for neutron resonance spectroscopy, are explained. To develop NRD for the characterization of rock- and particle like heterogeneous samples a JAEA/JRC collaboration has been established. As part of this collaboration a NRD demonstration workshop was organized at the TOF facility GELINA of the JRC-IRMM. The results of this workshop are presented. They illustrate the potential of measurements of complex mixtures of different elements. It is demonstrated that the elemental composition of an unknown sample predicted by NRTA deviated on average by less than 2% from the declared value. In addition the potential to identify the presence of light elements by NRCA is shown.

論文

NRDの開発,2; NRTAによる面密度測定に対するサンプル厚の系統的な影響の検証

土屋 晴文; 原田 秀郎; 小泉 光生; 北谷 文人; 高峰 潤; 呉田 昌俊; 飯村 秀紀; 木村 敦; Becker, B.*; Kopecky, S.*; et al.

核物質管理学会(INMM)日本支部第35回年次大会論文集(インターネット), 9 Pages, 2015/01

福島第一原子力発電所での過酷事故のような事例で発生するとされる粒子状溶融燃料デブリ中の核物質を非破壊で定量することを目的とし、中性子共鳴透過分析法(NRTA)と中性子共鳴捕獲$$gamma$$線分析法を合わせた中性子共鳴濃度分析法(NRD)を開発している。NRDの開発のために、IRMMの中性子飛行時間施設GELINAにて、NRTA実験を行った、実験では、サンプル厚の効果を調べるため、異なる厚みの銅サンプルを用い、混合物の影響を検証するために、銅にB$$_{4}$$Cを重ねたサンプルを用いた。銅の面密度を得るには、共鳴解析コードREFITを用いた。その結果、推奨共鳴パラメータを使った解析で得た面密度は、サンプルの質量や面積から計算した面密度から大きくずれるとわかった。そこで、実験データから銅の中性子幅を新たに求め、面密度が期待値と2%以内で一致することを確かめた。加えて、混合物のNRTA測定に与える影響も議論する。

論文

Impact of systematic effects on results of neutron resonance transmission analysis

土屋 晴文; 原田 秀郎; 小泉 光生; 北谷 文人; 高峰 潤; 呉田 昌俊; 飯村 秀紀; 木村 敦; Becker, B.*; Kopecky, S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 767, p.364 - 371, 2014/12

 被引用回数:6 パーセンタイル:36.56(Instruments & Instrumentation)

中性子共鳴吸収透過法(NRTA)による面密度の測定に対するサンプル厚の影響を検証するために、EC/JRC/IRMMの中性子飛行時間施設GELINAにおいて、NRTA実験を実施した。実験では、厚みの異なる円盤状の銅金属を用いて、GELINAの25m飛行導管を利用した。実験データから面密度を導出するために、共鳴解析コードREFITを用いて、共鳴解析を行った。その結果、推奨共鳴パラメータ値を用いると、求めた面密度が質量や面積から計算できる面密度から大きくずれることがわかった。そこで、0.25mm厚のサンプルを用いた実験データをREFIT用いて解析して、中性子幅と共鳴エネルギーを導出した。新たに求めた共鳴パラメータ値を使って、面密度を導出し、サンプルの厚みはもちろん、共鳴の強さが面密度の測定におよぼす影響を議論した。

論文

Measurement of the direct particle transport through stochastic media using neutron resonance transmission analysis

Becker, B.*; Kopecky, S.*; 原田 秀郎; Schillebeeckx, P.*

European Physical Journal Plus, 129(4), p.58_1 - 58_9, 2014/04

 被引用回数:11 パーセンタイル:28.13(Physics, Multidisciplinary)

A measurement of the uncollided neutron flux passing through a sample containing a stochastic mixture of tungsten and sulfur grains has been performed using neutron resonance transmission analysis in the 3-200 eV energy region. The impact of the heterogeneous characteristic of the sample is shown based on a comparison of the measurement with a calculated transmission spectrum of a homogeneous sample, which was verified by a measurement with a homogeneous metallic disc. By using a single strong resonance of tungsten, the particle self-shielding factor between 0.2-0.9 was directly measured. The experimental data have been compared with model calculations using the Markovian Levermore-Pomraning model. The measured transmission has been used to determine the effective characteristic chord length and volume fraction of the tungsten grains within the sample.

論文

Particle size inhomogeneity effect on neutron resonance densitometry

Becker, B.*; 原田 秀郎; Kauwenberghs, K.*; 北谷 文人; 小泉 光生; Kopecky, S.*; Moens, A.*; Schillebeeckx, P.*; Sibbens, G.*; 土屋 晴文

ESARDA Bulletin, (50), p.2 - 8, 2013/12

Neutron Resonance Densitometry (NRD) represents a possible option to determine the heavy metal content in melted nuclear fuel. This method is based on the well-established methodology of neutron time-of-flight (TOF) transmission and capture measurements. In particular, NRD can measure both the isotopic and the elemental composition. It is a non-destructive method and is applicable for highly radioactive material. The details of this method are explained in another contribution to this symposium. The accuracy of NRD depends among other factors on sample characteristics. Inhomogeneities such as density variations in powder samples can introduce a significant bias in the determination of the composition. In this contribution, the impact of the particle size distribution of such powder samples on results obtained with NRD is investigated. Various analytical models, describing the neutron transport through powder, are compared. Stochastic numerical simulations are used to select a specific model and to estimate the introduced model uncertainty. The results from these simulations will be verified by dedicated measurements at the TOF-facility GELINA of the EC-JRC-IRMM.

論文

Development of neutron resonance densitometry at the GELINA TOF facility

Schillebeeckx, P.*; Abousahl, S.*; Becker, B.*; Borella, A.*; Emiliani, F.*; 原田 秀郎; Kauwenberghs, K.*; 北谷 文人; 小泉 光生; Kopecky, S.*; et al.

ESARDA Bulletin, (50), p.9 - 17, 2013/12

Neutrons can be used as a tool to study properties of materials and objects. An evolving activity in this field concerns the existence of resonances in neutron induced reaction cross sections. These resonance structures are the basis of two analytical methods which have been developed at the EC-JRC-IRMM Neutron Resonance Capture Analysis (NRCA) and Neutron Resonance Transmission Analysis (NRTA). They have been applied to determine the elemental composition of archaeological objects and to characterize nuclear reference materials. A combination of NRTA and NRCA together with Prompt Gamma Neutron Analysis, referred to as Neutron Resonance Densitometry (NRD), is being studied as a non-destructive method to characterize particle-like debris of melted fuel that is formed in severe nuclear accidents such as the one which occurred at the Fukushima Daiichi Nuclear Power Plants. This study is part of a collaboration between JAEA and EC-JRC-IRMM. In this contribution the basic principles of NRTA and NRCA are explained based on the experience in the use of these methods at the time-of-flight facility GELINA of the EC-JRC-IRMM. Specific problems related to the analysis of samples resulting from melted fuel are discussed. The programme to study and solve these problems is described and results of a first measurement campaign at GELINA are given.

論文

Contribution of the JRC to the development of neutron resonance densitometry to characterize melted fuel from severe accidents

Schillebeeckx, P.*; Becker, B.*; Emiliani, F.*; Kopecky, S.*; Kauwenberghs, K.*; Moens, A.*; Mondelaers, W.*; Sibbens, G.*; 原田 秀郎; 北谷 文人; et al.

Proceedings of INMM 54th Annual Meeting (CD-ROM), 7 Pages, 2013/07

Neutron resonance densitometry (NRD) is proposed as a non-destructive method to characterize particle like debris originating from severe nuclear accidents such as the one occurred at the Fukushima Daiichi Nuclear Power Plants. The method strongly relies on the use of Neutron Resonance Transmission Analysis (NRTA) to quantify the amount of special nuclear materials present in the debris. In this contribution the basic principles of NRTA are explained based on measurements performed at the time-of-flight facility GELINA installed at the EC-JRC-IRMM. In addition, the main systematic effects affecting the accuracy of the results are discussed, with a special emphasis on the variety in shape and size of the particle like debris samples. To verify the impact of the particle size distribution various analytical models have been compared and validated by results of both stochastic numerical calculations and NRTA experiments at GELINA. Results of a preliminary analysis of the experimental data are presented.

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