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Rodriguez, D.; Abbas, K.*; 小泉 光生; Nonneman, S.*; Rossi, F.; 高橋 時音
Nuclear Instruments and Methods in Physics Research A, 1014, p.165685_1 - 165685_10, 2021/10
被引用回数：1 パーセンタイル：32.08(Instruments & Instrumentation)Under the MEXT subsidy on research for improving nuclear security related development, we designed the Delayed Gamma-ray Californium Test (DGCT) instrument. From He-3 count-rate experiments performed in collaboration with the European Commission Joint Research Centre, we show the effective neutron flux entering the sample space. Further, we show delayed gamma-ray spectra of both U and Pu samples as well as a comparison to the background from Cf activation of the environment. Finally, we make comparisons to earlier spectra obtained using PUNITA, including relative fission capability, spectral signature, and mass correlations.
Rodriguez, D.; Bogucarska, T.*; 小泉 光生; Lee, H.-J.; Pedersen, B.*; Rossi, F.; 高橋 時音; Varasano, G.*
Nuclear Instruments and Methods in Physics Research A, 997, p.165146_1 - 165146_13, 2021/05
被引用回数：1 パーセンタイル：32.08(Instruments & Instrumentation)Under the MEXT subsidy to strengthen nuclear security related research, the ISCN is developing delayed gamma-ray spectroscopy (DGS) for nuclear safeguards. Here we present results from experiments using the PUNITA instrument in collaboration with JRC-Ispra to evaluate the gamma-ray spectral dependence on interrogation time patterns and number of cycles. Specifically, we investigated the observable gamma rays useful to quantify the 
Pu and 
U contributions. Of the time patterns tested in this study, we determined that irradiating the sample for 60-
followed by a gamma-ray measurement of 60- was the best for a comparable one-hour total interrogation time.
Rodriguez, D.; 小泉 光生; Rossi, F.; 瀬谷 道夫; 高橋 時音; Bogucarska, T.*; Crochemore, J.-M.*; Pedersen, B.*; 高峰 潤
Journal of Nuclear Science and Technology, 57(8), p.975 - 988, 2020/08
被引用回数：3 パーセンタイル：47.69(Nuclear Science & Technology)Present safeguards verification methods of high-radioactivity nuclear material use destructive analysis techniques since passive nondestructive techniques are incapable of determining the nuclear material content. To improve this verification process, the JAEA and EC-JRC Ispra, Italy have been collaborating to develop delayed gamma-ray spectroscopy for composition analysis of the fissile nuclides as an aspect of the MEXT subsidy for improving nuclear security and the like. Multiple experiments were performed over three years using PUNITA to interrogate U and Pu samples to determine the signature from the short-lived fission products. We observed many gamma rays useful to determine the composition of a mixed nuclear material sample. Presented here are the results of these measurements with correlations to the interrogation, mass, volume, and sample homogeneity.
Cf for safeguards verification measurementsRodriguez, D.; Rossi, F.; 高橋 時音; 瀬谷 道夫; 小泉 光生
Applied Radiation and Isotopes, 148, p.114 - 125, 2019/06
被引用回数：5 パーセンタイル：58.93(Chemistry, Inorganic & Nuclear)Delayed gamma-ray spectroscopy is an active-NDA technique used to determine the composition of HRNM samples by peak-ratio comparison of GRs above 3-MeV from the short-lived fission products. Filtering out the passive GRs from long-lived FPs reduces the DGS signal, so thermal neutrons are used to induce more fission events from fissile nuclides. We are developing a compact system to moderate 
2-MeV neutrons that are easier to moderate than 14-MeV neutrons from DT generators. This work describes the ideal moderator optimization for a Cf source that results in 
cm
passing through the sample space with 
70% of those below 1-eV. Practical modifications resulted in 
20% reductions compared to the optimized design. Evaluations of DGS signals and backgrounds conclude that only a 21-MBq Cf source is required.
Rodriguez, D.; Rossi, F.; 高橋 時音; 瀬谷 道夫; 小泉 光生; Crochemore, J. M.*; Varasano, G.*; Bogucarska, T.*; Abbas, K.*; Pedersen, B.*
Proceedings of INMM 59th Annual Meeting (Internet), 7 Pages, 2018/07
DGS has great potential for HRNM, since it determines fissile nuclide compositions by correlating the observed DG spectrum to the unique FY of the individual nuclides. Experiments were performed with LRNM using both PUNITA and a JAEA designed Cf-shuffler tested in PERLA. The data was analyzed using an inverse MC method that both determines DG peak intensity correlations and provides an evaluation of the uncertainty of the measurements. The results were used to verify DG signatures for varying fissile compositions, total fissile content, and DGS interrogation timing patterns. Future development will focus on measuring HRNM and designing a compact system by evaluating different neutron sources, moderating materials, and detection capabilities. This presentation summarizes the JAEA/JRC DGS program to date and the future direction of this collaborative work performed using the MEXT subsidy for the promotion of strengthening nuclear security.
Rodriguez, D.; Rossi, F.; 高峰 潤; 小泉 光生; 瀬谷 道夫; Crochemore, J. M.*; Varasano, G.*; Bogucarska, T.*; Abbas, K.*; Pedersen, B.*
Proceedings of INMM 58th Annual Meeting (Internet), 6 Pages, 2017/07
原子力機構は、4つのアクティブ法を組合せたNDAシステムの開発をEC-JRCと共同で実施している。遅発
線分光法は核分裂性核種の組成比を決定することができるもので、観測する核分裂生成核種の時間依存型の、高エネルギー線を、サンプルの複雑な核分裂収率と関連付けて分析するものである。興味のある核分裂性核種比を定量するためには、使用する(小型の持ち運びが可能な)中性子源からの速中性子を、核分裂反応断面積の大きな熱中性子までエネルギーを下げつつ、有意な計数信号を得るためのフラックス強度を必要とする。現在、遅発線分光法の改良のため、JRC-IspraのPUNITAを含むいくつかの施設での実験が進行中である。これらの中性子フラックス、測定環境等データは、遅発線分光データの分析を行うモンテカルロ法(逆モンテカルロ法)の開発に使われる。ここでの遅発線分光法は、その実証に関して、これまでの開発成果である減速系の最適化、実験、逆モンテカルロ法についてまとめる。
Rossi, F.; Abbas, K.*; 小泉 光生; Lee, H.-J.; Nonneman, S.*; Pedersen, B.*; Rodriguez, D.; 高橋 時音
no journal, ,
In the field of nuclear material samples safeguard verifications, mixed high-radioactivity nuclear material in facility like reprocessing nuclear plant are challenging. Addressing this, the JAEA/ISCN is developing a DG-nondestructive assay technique. We successfully completed several experiments in collaboration with the EC/JRC to evaluate the instrumentation requirements of a compact instrument. In principle, a neutron source is used to produce neutrons that are then thermalized in a moderator before reaching the sample to induce fission. The optimization of the moderator is crucial to reach an efficient and compact instrument. Having a good thermalized neutron flux enhances the delayed gamma-ray signature of the fissile due to their greater thermal fission cross section compared to the fertile. After the irradiation, the gamma-ray peaks above 3 MeV are analyzed to determine the initial composition of the fissile nuclides. The gamma-ray spectrum and subsequent analysis are strongly affected by the source type; the sample; and the interrogation pattern, driven by the analysis. To investigate all these aspects, we performed several experiments using small standard samples of both Uranium and Plutonium with PUNITA to understand basic principles. These were factored into the JAEA DGCT instrument that was tested in PERLA. This work first describes the PUNITA and PERLA experiments and how these were used to validate the various model designs. From these, further modifications to reach our final instrument concept design for a deuterium-deuterium neutron generator source are presented. This work is supported by MEXT under the subsidy for the "promotion for strengthening nuclear security and the like". This work was done under the agreement between JAEA and EURATOM in the field of nuclear material safeguards research and development.
