Overall approaches and experiences of first-time participants in the Nuclear Forensics International Technical Working Group's Fourth Collaborative Material Exercise (CMX-4)

Ho, D. M. L.*; Nelwamondo, A. N.*; Okubo, Ayako; Ramebck, H.*; Song, K.*; Han, S.-H.*; Hancke, J. J.*; Holmgren, S.*; Jonsson, S.*; Kataoka, Osamu; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.353 - 363, 2018/02

https://doi.org/10.1007/s10967-017-5677-0

The Fourth Collaborative Material Exercise (CMX-4) of the Nuclear Forensics International Technical Working Group (ITWG) registered the largest participation for this exercise in nuclear forensics, with seven of the 17 laboratories participating for the first time. In this paper, participants from five of the first-time laboratories shared their individual experience in this exercise, from preparation to analysis of samples. The exercise proved to be highly useful for testing procedures, repurposing established methods, exercising skills, and improving the understanding of nuclear forensic signatures and their interpretation trough the post-exercise review meeting.

Uranium age-dating using in-situ isotope ratios by thermal ionization mass spectrometry for nuclear forensics

Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki

Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.231 - 234, 2017/10

https://doi.org/10.1007/s10967-017-5379-7

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.

Technical/institutional prerequisite for nuclear forensics response framework

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.

Current status and achievements on nuclear forensics technology developments for nuclear security

Kimura, Yoshiki; Shinohara, Nobuo; Okubo, Ayako

Nihon Genshiryoku Gakkai-Shi ATOMO, 57(12), p.782 - 786, 2015/12

no abstracts in English

Rapid collection of iron hydroxide for determination of Th isotopes in seawater

Okubo, Ayako; Obata, Hajime*; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi*

Analytica Chimica Acta, 804, p.120 - 125, 2013/12

https://doi.org/10.1016/j.aca.2013.10.004

This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were coprecipitated with iron hydroxide, and this precipitate was sent to chelating resin column. The chelating column quantitatively collected Th with iron hydroxide in seawater at flow rates of 20-25 mL/min. Based on this flow rate, a 5 L sample was processed within 3-4 h.

Th and Th distributions in mid-latitudes of the North Pacific Ocean; Effect of bottom scavenging

Okubo, Ayako; Obata, Hajime*; Gamo, Toshitaka*; Yamada, Masatoshi*

Earth and Planetary Science Letters, 339-340, p.139 - 150, 2012/07

https://doi.org/10.1016/j.epsl.2012.05.012

Vertical distributions of total Th and dissolved Th were determined in the mid-latitudes of the North Pacific Ocean. Th in the Pacific Ocean have been described well using the reversible-scavenging model. However, we observed the depletion of total Th. The enhanced vertical eddy diffusion derived from the complex topography of the western Pacific Ocean might promote bottom scavenging and transport of the low Th in deep water to the upper layers.

Readiness for nuclear terrorism; Nuclear forensics framework in advanced nations

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.

Joint sample analysis on selected uranium ore concentrates and nuclear forensics library exercise

Kips, R.*; Lindvall, R.*; Marks, N.*; Gluschenko, V.*; Okubo, Ayako; Szeles, E.*

no journal, , 

Current status and future prospects on nuclear forensics technology development in ISCN-JAEA

Kimura, Yoshiki; Okubo, Ayako; Tomikawa, Hirofumi; Matsumoto, Tetsuya*; Umino, Yuji*; Hosoi, Masaharu*

no journal, , 

Present status of R&D on nuclear forensics at JAEA

Sakurai, Satoshi; Kimura, Yoshiki; Sato, Kaneaki; Toda, Nobufumi; Shinoda, Yoshiharu; Okubo, Ayako; Magara, Masaaki; Watahiki, Masaru; Kuno, Yusuke

no journal, , 

The national statement made by the Japan Government at 2010 Nuclear Security Summit (Washington D.C., U.S.A.) was to develop its nuclear forensics detection and analysis technologies in a three-year period and to share them with the international community to contribute to strengthening the nuclear security regime. The Japan Atomic Energy Agency, the organization that possesses analytical capabilities with the potential to fulfill this nuclear forensics mission, started R&D on nuclear forensics technology from JFY 2011. The main areas of development are isotopic ratio analysis, impurity analysis, uranium age determination, etc. The cooperation with US-DOE and EC-JRC were also started to effectively promote the technical development. In the presentation reported will be progress in R&D to establish nuclear forensics analytical capabilities and international cooperation.