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Tomikawa, Hirofumi; Koizumi, Mitsuo; Tamai, Hiroshi
Genshiryoku Heiwa Riyo To Kakufukakusan, Kakusekyuritei; NSA/Commentaries, No.25, p.167 - 174, 2020/06
Japan's efforts for research and development on nuclear material detection and nuclear forensics and international cooperation are introduced focusing on the various aspects implemented in JAEA.
Kimura, Yoshiki; Matsui, Yoshiki; Tomikawa, Hirofumi
ITWG Nuclear Forensics Update (Internet), (15), p.4 - 7, 2020/06
Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki
Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.231 - 234, 2017/10
Times Cited Count:2 Percentile:19.37(Chemistry, Analytical)The model date of two enriched uranium materials were determined using a new method for nuclear forensics investigation. In this method, the Th/U ratio was calculated without spike addition from measured ratios of Th/Th and U/U, and calculated Th/U ratio in secular equilibrium. The obtained model date for the low-enriched uranium material was agreed with the known production date within uncertainty. For the highly enriched uranium material, slightly younger model date than the known production date was obtained. The U interference on Th counting in thermal ionization mass spectrometry measurement was suspected as a potential cause.
Tamai, Hiroshi; Okubo, Ayako; Kimura, Yoshiki; Shinohara, Nobuo; Tazaki, Makiko; Shimizu, Ryo; Suda, Kazunori; Tomikawa, Hirofumi
Proceedings of INMM 58th Annual Meeting (Internet), 6 Pages, 2017/07
Nuclear forensics is a technical measure to analyse and collate samples of illegally used nuclear materials, etc., to clarify their origins, routes, etc. and contribute to criminal identifications. Close collaboration with police and judicial organizations is essential. The national response framework is being built up with international cooperation. Discussions on promoting technical capability and regional cooperation are presented.
Tamai, Hiroshi
Hiroshima Repoto 2017-Nen Ban; Kakugunshuku, Kakufukakusan, Kakusekyuritei O Meguru 2016-Nen No Doko, p.163 - 165, 2017/03
The series of Nuclear Security Summit, initiated by President Barack Obama, was held biennially, four times since 2010, and played an important role in promoting international efforts to enhance nuclear security. Despite Russia's refusal to participate in the fourth meeting, these summit-level meetings have gained both international and domestic attention, which have led to remarkable improvements in the field of nuclear security of each participating country. Therefore, there is an urgent need to take continuous measures to keep this momentum alive even after the final Nuclear Security Summit concluded in 2016. The challenges in strengthening nuclear security, prospects in the post-Nuclear Security Summit phase, as well as efforts and measures that Japan should pursue are investigated.
Tamai, Hiroshi; Okubo, Ayako; Kimura, Yoshiki; Kokaji, Lisa; Shinohara, Nobuo; Tomikawa, Hirofumi
Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu (CD-ROM), 8 Pages, 2017/02
Nuclear Forensics capability has been developed under the international collaborations. For its effective function, technical development in analysis of seized nuclear materials as well as the institutional development in comprehensive response framework are required under individual national responsibility. In order to keep the "chain of custody" in the proper operation of sample collection at the event scene, radiological analysis at the laboratory, storage of the samples, and further inspection and trial, close cooperation and information sharing between relevant organisations are essential. IAEA issues the Implementing Guide to provide the model action plan and assists individual national development. International cooperation for the technical improvement and awareness cultivation is promoted. Examples in such national developments will be introduced and prospective technical/institutional prerequisite for nuclear forensics response framework will be studied.
Gaffney, A.*; Hubert, A.*; Kinman, W. S.*; Magara, Masaaki; Okubo, Ayako; Pointurier, F.*; Schorzman, K. C.*; Steiner, R. E.*; Williams, R. W.*
Journal of Radioanalytical and Nuclear Chemistry, 307(3), p.2055 - 2060, 2016/03
Times Cited Count:22 Percentile:89.61(Chemistry, Analytical)In and inter-laboratory measurement comparison study, four laboratories (LLNL, LANL, CEA, JAEA) determined Th-U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. These model ages are concordant with to slightly older than the known production age of NBL U050, indicating unsufficient purification of U050.
Asai, Shiho; Limbeck, A.*
no journal, ,
no abstracts in English
Asai, Shiho; Limbeck, A.*
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Okubo, Ayako; Esaka, Fumitaka; Magara, Masaaki; Shinohara, Nobuo
no journal, ,
To elucidate the final purification date of uranium material namely age-dating is important subject on nuclear forensic analysis. Age-dating of uranium using U-Th nuclide pair was established in the field of geochemical science, and has been applied for nuclear forensics. Recently, safeguard analysis also demand age-dating of uranium materials. In order to measure a small amount of Th by ICP-MS, anion exchange column separation is commonly conducted to eliminate U tailing effect. However, column separation step could raise procedural blank of Th. In contrast, TIMS can separately ionize U and Th in filament heating step using the difference of optical ionization temperature of these elements. We developed analytical method for age-dating of single particle uranium material by TIMS.
Okubo, Ayako; Shinohara, Nobuo; Toda, Nobufumi; Kataoka, Osamu; Matsumoto, Tetsuya
no journal, ,
no abstracts in English
Shinohara, Nobuo; Kimura, Yoshiki; Okubo, Ayako
no journal, ,
Nuclear forensics is the analysis of intercepted illicit nuclear or radioactive material and any associated material to provide evidence for nuclear attribution by determining origin, history, transit routes and purpose involving such material. Because the nuclear forensics methodologies provide hints of the origin of the nuclear materials used in illegal dealings or nuclear terrorism, it contributes to identify and indict offenders, hence to enhance deterrent effect against such terrorism. In the 59th Symposium on Radiochemistry, the results of research and development of fundamental nuclear forensics technologies (analysis of isotopic composition, impurity analysis, age dating of nuclear material, particle shape analysis by electron microscope, and nuclear forensics library) performed in Japan Atomic Energy Agency are reported. Japan's capability and the role of radiochemistry on nuclear forensics are also discussed in the Symposium.
Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki
no journal, ,
The uranium age-dating is a nuclear forensics analysis techniques, by measuring the Th / U isotope ratio in uranium sample, to estimate the elapsed time from being separated and purified. We have determined Th and U using isotope dilution mass spectrometry method, it has conducted for uranium age-dating. Act to perform the isotope analysis after the addition a known quantity of the isotope (spike) to the sample, after spiking, analytical sample is assumed to be in the state of isotopic equilibrium. However, the samples which have complex speciation of uranium and thorium are analyzed, may not sufficiently reach to the state of isotopic equilibrium has been suggested from the experimental results. In this study, without the addition of a spike, from the measurement results of the uranium isotope ratios and thorium isotope ratio in the sample, it was investigated a method for calculating the Th / U isotope ratio. The state of radioactive equilibrium between U and Th in the sample was utilized in the Th / Th method. The Th / U ratio was calculated using measured Th / Th isotope ratio, U / U isotope ratio and Th / U ratio in the radioactive equilibrium.
Tamai, Hiroshi; Kimura, Yoshiki; Okubo, Ayako; Shinohara, Nobuo; Tomikawa, Hirofumi
no journal, ,
Nuclear forensics is effective measure for strengthening nuclear security through the analysis of origin and characteristics of nuclear materials or radio-isotopes collected at the crime scene inspections. In the development of nuclear forensics laboratory/library, "Chain of Custody" should be kept in mind on the view point of juridical process. Each nation should develop own national response plan to stipulate the framework for integrated nuclear forensics activities. Good practices for stipulating national frameworks for nuclear forensics are investigated in advancing nations such as US, EU and Canada. Issues and measures are proposed aiming at improving its framework.
Okubo, Ayako; Shinohara, Nobuo; Umino, Yuji; Hara, Mikiya
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Kimura, Yoshiki; Shinohara, Nobuo; Matsumoto, Tetsuya*
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no abstracts in English
Okubo, Ayako; Mayer, K.*
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Under the collaboration between EC-JRC and JAEA, the in-situ age dating method was subject to joint validation, and six different uranium materialswere used for this purpose. The age dating result by in-situ isotope method was consistent with known production dates of the respective samples. The uncertainty evaluation according to GUM for the in-situ isotope method indicates that the measured Th/Th ratio provides the highest contribution. The accuracy of in-situ isotope method can be improved by higher precision in Th/Th measurement.
Tomikawa, Hirofumi; Kimura, Yoshiki; Okubo, Ayako
no journal, ,
Kips, R.*; Lindvall, R.*; Marks, N.*; Gluschenko, V.*; Okubo, Ayako; Szeles, E.*
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Kimura, Yoshiki; Tsuchiya, Kenichi*; Okubo, Ayako*; Tanabe, Kosuke*; Kakuda, Hidetoshi*; Akiba, Norimitsu*; Tomikawa, Hirofumi
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