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Journal Articles

Local structure analysis of KNbO$$_3$$ nanocubes by solvothermal synthesis

Yoneda, Yasuhiro; Kohara, Shinji*; Nakashima, Koichi*; Nagata, Hajime*; Wada, Satoshi*

Japanese Journal of Applied Physics, 54(10S), p.10NC01_1 - 10NC01_6, 2015/10

 Times Cited Count:4 Percentile:18.73(Physics, Applied)

The atomic-scale structure of KNbO$$_3$$ nanopowder synthesized by solvothermal method has been studied using high-energy X-ray diffraction, Rietveld refinement, and the atomic pair-distribution function (PDF) technique. It was found that the local structure of KNbO$$_3$$ nanoparticles deviates from the average structure. The local structure was found to be rhombohedral structure though the average structure was tetragonal structure. The rhombohedral distortion of NbO$$_6$$ octahedra was maintained in the annealed sample.

Journal Articles

JAEA's contribution to development of J-MOX safeguards system

Nagatani, Taketeru; Nakajima, Shinji; Kawakubo, Yoko; Shiromo, Hideo; Asano, Takashi; Marlow, J.*; Swinhoe, M. T.*; Menlove, H.*; Rael, C.*; Kawasue, Akane*; et al.

Book of Abstracts, Presentations and Papers of Symposium on International Safeguards; Linking Strategy, Implementation and People (Internet), 8 Pages, 2015/03

Journal Articles

Monte Carlo N-Particle eXtended (MCNPX) simulation for passive neutron measurement of fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

Meltdown of the reactor cores of Units 1-3 occurred at Fukushima Daiichi Nuclear Power Plants (1F). Fuel debris at 1F contains minor actinides and fission products and neutron absorber. These materials make it difficult to quantify fertile nuclear materials in fuel debris by the conventional passive neutron technique. We consider that DDSI and PNAR which focused on fissile material are promising techniques to quantify the nuclear materials in the fuel debris. A concept of application of these techniques to fuel debris measurement was investigated and presented at the last INMM annual meeting. In order to evaluate the applicability of these techniques to fuel debris measurement, we investigated the neutron behavior in the fuel debris by using MCNPX simulation code. Because property of fuel debris is not clear, source term data used were prepared by referring TMI data. This paper provides results of MCNPX simulation for fuel debris measurement at 1F with passive neutron techniques.

Journal Articles

Performance test results for the Advanced Fuel Assembly Assay System (AFAS) on the active length verification of LWR MOX fuel assembly by neutron detectors

Nakajima, Shinji; Nagatani, Taketeru; Shiromo, Hideo; Asano, Takashi; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; Rael, C. D.*; Kawasue, Akane*; Iso, Shoko*; et al.

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

The Advanced Fuel Assembly Assay System (AFAS) is an unattended non-destructive assay (NDA) system by neutron measurement to verify the plutonium amount in an LWR plutonium and uranium mixed oxide (MOX) fuel assembly. The assembly will be fabricated in the MOX fuel fabrication plant under construction by the Japan Nuclear Fuel Limited. The AFAS has been developed by Los Alamos National Laboratory under the auspices of the Secretariat of Nuclear Regulation Authority in Japan. The AFAS is the first NDA system which will verify the active length of the assembly without inspector attendance. Japan Atomic Energy Agency (JAEA) has conducted the performance test for the AFAS under the contract with Nuclear Material Control Center to demonstrate this active length verification technology by using MOX fuel assemblies owned by JAEA. As the results, it was confirmed that measurement error of the active length for the MOX fuel assembly was less than 0.1% and it was satisfied with requirement by IAEA. This paper provides the performance test results for the active length verification of the AFAS.

Journal Articles

Performance test results of the Advanced Verification for Inventory Sample System (AVIS), 2

Nakajima, Shinji; Nagatani, Taketeru; Asano, Takashi; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; Watanabe, Takehito*; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; et al.

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

The Advanced Verification for Inventory Sample System (AVIS) is a nondestructive assay (NDA) system in order to verify the plutonium mass in the small MOX samples at Japan Nuclear Fuel Limited (JNFL) MOX fuel fabrication plant (J-MOX) under construction. The AVIS is required the high measurement performance because the AVIS will be used as a verification tool to substitute destructive analysis for a part of the samples which needs the bias defect verification. Therefore, the AVIS will fulfill an important role in the safeguards approach for J-MOX. Japan Atomic Energy Agency (JAEA) conducted the performance test of the AVIS under the contract with NMCC. As the results of these tests, we confirmed that the AVIS could almost satisfy the required performance by IAEA.

Journal Articles

Feasibility study on passive neutron technique applied to fuel debris measurement at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Asano, Takashi

Proceedings of INMM 54th Annual Meeting (CD-ROM), 8 Pages, 2013/07

Fukushima Daiichi Nuclear Power Plants (1F) were struck by the earthquake and tsunami on March 11, 2011 and meltdown of the reactor cores of Units 1-3 occurred. Japan decided decommissioning of them. For decommissioning of 1F, Japan plans to recover fuel debris safely and to account nuclear material in it adequately. Survey of applicable technologies for nuclear material quantification of fuel debris, currently, is being conducted by Japan Atomic Energy Agency (JAEA) and United States Department of Energy (DOE) under the collaborative agreement. This survey will identify technologies with the most promising capability to meet IAEA safeguards needs. As one of candidate technologies of plutonium quantification in fuel debris, we, Plutonium Fuel Development Center of JAEA, consider the application of the passive neutron technique which is wildly applied to the field of material accountancy and safeguards in plutonium handing facilities. Fuel debris contains minor actinides and fission products which are intense neutron and $$gamma$$ ray emitter due to burn-up of fuel in the reactor. It also contains neutron absorber such as gadolinium included in fuel to moderate burn-up and boron added after accident to avoid re-criticality. These materials make it difficult to quantify plutonium by the current passive neutron technique. Therefore, R&D activities regarding selective counting for neutron derived from plutonium, reduction of $$gamma$$ ray influence and estimation of neutron absorber influence are required in order to overcome above difficulties. This paper provides a concept for application of passive neutron technique to fuel debris measurement.

Journal Articles

Performance test results of the advanced verification for inventory sample system (AVIS)

Nakajima, Shinji; Nagatani, Taketeru; Asano, Takashi; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; Rael, C. D.*; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; et al.

Proceedings of INMM 54th Annual Meeting (CD-ROM), 10 Pages, 2013/07

The advanced verification inventory system (AVIS) is a nondestructive assay (NDA) system developed by Los Alamos National Laboratory (LANL) to measure small samples of bulk plutonium and uranium mixed oxide (MOX) powder and pellets at the Japan Nuclear Fuel Limited (JNFL) mixed oxide fuel fabrication plant (J-MOX). In order to mitigate the workload on the Rokkasho On-Site Laboratory (OSL), it is intended that the AVIS measurement will be substituted for a part of the Destructive Assay (DA) for J-MOX. Based on the commission from Office for Nuclear Non-Proliferation and Safeguards (JSGO) of Ministry of Education, Culture, Sports, Science and Technology (MEXT) and Nuclear Material Control Center (NMCC), Japan Atomic Energy Agency (JAEA) has conducted the performance test of the AVIS in order to confirm the system performance before installation at the J-MOX site. The performance test consists of two phases. In the phase 1 test, detector parameters such as detector efficiency and die-away time were evaluated by using a californium-252 neutron source. These results agreed well with design value and were reported at the 53rd INMM annual meeting. JAEA conducted the phase 2 test by using MOX materials in order to evaluate the total measurement uncertainty (TMU). In the test, influence of sample density, plutonium concentration and organic additives in samples were also evaluated. Consequently, it is expected that AVIS can achieve the target TMU of 0.5% required in user requirement of IAEA by optimizing measurement condition and by using well-characterized standards. This paper provides a summary of the results of comprehensive performance test of AVIS.

Journal Articles

Interim report of performance test of the advanced verification for inventory sample system (AVIS)

Nagatani, Taketeru; Nakajima, Shinji; Asano, Takashi; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; Rael, C. D.*; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; et al.

Proceedings of INMM 53rd Annual Meeting (CD-ROM), 9 Pages, 2012/07

The advanced verification for inventory sample system (AVIS) is a nondestructive assay (NDA) system designed to measure small samples of bulk plutonium uranium mixed oxide (MOX) powder and pellets at the proposed Japan Nuclear Fuel Limited (JNFL) mixed oxide fuel fabrication plant (J-MOX). The system consists of a $$^{3}$$He-based passive neutron well counter with an integrated high-purity germanium $$gamma$$ system. The AVIS is intended to meet a performance specification of a total measurement uncertainty of less than 0.5% in the neutron ($$^{240}$$Pu effective) measurement. It is intended that the AVIS measurement will be substituted for a fraction of the DA samples from J-MOX. JAEA has conducted performance testing on the AVIS in order to confirm the system performance before installation and to minimize the period of calibration at J-MOX site. In this paper, we provide a summary of the result of performance test phase 1 and the test plan of performance test phase 2 of the AVIS.

Journal Articles

Experience on implementation of the Integrated Safeguards approach for the MOX facility from the operator's point of view

Nomi, Takayoshi; Nagatani, Taketeru; Ninagawa, Junichi; Nakajima, Shinji; Maruyama, Hajime; Asano, Takashi; Fujiwara, Shigeo

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2011/11

The IS approach for the JNC-1 site was implemented in August 2008, and this was the first experience in the world. This IS approach aimed not only to improve efficiency and effectiveness of safeguards but also to reduce burden of the plant operation by improvement of efficiency of the inspection activity. It was planned to review effectiveness of this new approach after three years from implementation. And JAEA also evaluated effects by application of the IS approach for two MOX fuel facilities in the JNC-1 site based on the three years experiences from the operator's view point. As the result of evaluation, it was confirmed that there were some difference of benefits by application of the IS approach depending on features of the facility, automation level of equipment and advance level of safeguards systems.

Journal Articles

Evaluation of application effect of the integrated safeguards approach for MOX fuel fabrication facilities from the operator's viewpoint

Ninagawa, Junichi; Asano, Takashi; Nagatani, Taketeru; Nakajima, Shinji; Nomi, Takayoshi; Fujiwara, Shigeo

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 8 Pages, 2011/07

Japan was transferred to the Integrated Safeguards (IS) scheme in September 2004. The IS approach for JNC-1 site, including PFPF, was developed to improve the efficiency of safeguards while maintaining the effectiveness and has been implemented since August 2008. JAEA has evaluated the validity of the IS approach for PFPF based on the historical performance over about three-year period. As the result of evaluation, JAEA confirmed the improvement of efficiency of inspection activities and the reduction of the impact of inspection activities on plant operation. On the other hand, the IAEA has also evaluated the validity of IS approach and considered to modify based on the result of its evaluation. In order to maintain or improve the validity of the IS approach, JAEA thinks that it will be necessary to work very closely and honestly with the inspectorate to address this modification process.

Journal Articles

High-accuracy measurement of plutonium mass by non-destructive assay; An Improved approach for the effectiveness and efficiency of safeguards

Nagatani, Taketeru; Nakajima, Shinji; Asano, Takashi; Fujiwara, Shigeo; Menlove, H. O.*; Swinhoe, M. T.*; Browne, M. C.*

Journal of Nuclear Materials Management, 39(3), p.4 - 10, 2011/04

Journal Articles

Performance test of ENMC (Epithermal Neutron Multiplicity Counter), phase II

Ninagawa, Junichi; Asano, Takashi; Fujiwara, Shigeo; Takahashi, Saburo; Menlove, H.*; Rael, C. D.*; Nakajima, Shinji*; Sato, Takashi*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-27-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2006/00

no abstracts in English

Oral presentation

Low-energy dynamics in silicate glasses

Suzuya, Kentaro; Nakamura, Mitsutaka; Nakajima, Kenji; Kohara, Shinji*; Kikuchi, Tatsuya; Kawamura, Seiko; Inamura, Yasuhiro; Shibata, Kaoru*

no journal, , 

The origin of low energy dynamics termed Boson peak in glasses has long been controversial and hence it is necessary to reveal the relationship between glass structure and low energy dynamics. Inelastic neutron scattering (INS) using time-of-flight chopper spectrometer with a pulsed neutron source is a very powerful tool for the investigation of excitations in glasses. We discuss the relationship between the low energy excitations of silicate glasses (SiO$$_{2}$$ and PbO-SiO$$_{2}$$) from S(Q,E) maps obtained by time-of-flight measurements at AMATERAS spectrometer J-PARC and the structure on the basis of large atomic configuration derived from reverse Monte Carlo (RMC) modelling employing neutron and X-ray diffraction data with special focus on ring statistics, cavity volume, and connectivity of short-range structural units (polyhedra).

Oral presentation

Interim report on the performance test results for the Advanced Verification for Inventory sample System (AVIS)

Nagatani, Taketeru; Nakajima, Shinji; Asano, Takashi; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; Watanabe, Takehito*; Marlow, J.*; Martyn, S.*; Menlove, H.*; et al.

no journal, , 

The AVIS (Advanced Verification for Inventory sample System), which was designed by LANL in partnership with Nuclear Material Control Center (NMCC), is a nondestructive assay (NDA) system to measure the plutonium mass for plutonium uranium mixed oxide (MOX) powder and pellet for large scale MOX fuel fabrication plant (J-MOX). The AVIS is intended to meet a performance specification of a total measurement uncertainty of less than 0.5% in the neutron ($$^{240}$$Pu effective) measurement. It is intended that the AVIS measurement will be substituted for a fraction of the DA samples to reduce the number of DA from J-MOX. Therefore, the AVIS has a crucial role to attain effective safeguards for J-MOX. JAEA, which has experience/knowledge to develop the NDA system and plutonium handling field, was entrusted with performance testing for the AVIS from NMCC. JAEA has conducted performance testing on the AVIS using standard radiation source (neutron and $$gamma$$). As the results of test, it was confirmed that the AVIS has the designed performance. As a next step, JAEA will conduct the AVIS test using MOX materials in order to evaluate the relevant measurement accuracy. This paper reports the performance test results and future MOX test plans of the AVIS.

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