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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

JAEA and EC-JRC started a collaboration to study Neutron Resonance Densitometry (NRD) as a method for the characterization of melted fuel formed in nuclear accidents. NRD is based on a combination of Neutron Resonance Transmission Analysis (NRTA) and Neutron Resonance Capture Analysis (NRCA). In this presentation, the contribution of the EC-JRC-IRMM to the project is discussed. Within the project the GELINA facility will be used to validate the method and perform tests on calibration and test samples. In a first exercise the test samples will not contain actinides, however, they will contain nuclides having similar characteristics as the melted fuel for NRCA and NRTA. These samples will be produced and characterized at dedicated laboratories of our institute. To study the impact of the sample characteristics, in particular the particle size distribution of powder samples, various analytic models are compared. In addition stochastic simulations are used to select a specific model and to estimate the uncertainties introduced by the model. The stochastic model is also used to verify bias effects due to sample properties. The results of the simulations are verified by measurements at GELINA. In addition, the data reduction and analysis procedures will be adapted such that they can be used for in-field application of NRD. The changes required for NRD applications are discussed.

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.

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

Proceedings of 35th ESARDA Annual Meeting (Internet), 7 Pages, 2013/05

Neutron Resonance Densitometry (NRD) represents a possible option to determine the heavy metal content in melted nuclear fuel. It is a non-destructive method and is applicable for highly radioactive material. 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.

Proceedings of 35th ESARDA Annual Meeting (Internet), 11 Pages, 2013/05

Neutron Resonance Capture Analysis (NRCA) and Neutron Resonance Transmission Analysis (NRTA) have been applied to determine the elemental composition of archaeological objects and to characterize nuclear reference materials. A combination of NRTA and NRCA, 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.

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