The Application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Ramebck, H.*; Nelwamondo, A. N.*; Kotze, D.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.425 - 434, 2018/02

https://doi.org/10.1007/s10967-017-5680-5

In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the U-Pa and U-Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions.

Prospective features for integration of nuclear forensics capability in national framework

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.

Round-robin Th-U age dating of bulk uranium for nuclear forensics

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

https://doi.org/10.1007/s10967-015-4334-8

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.

On-site training using JMTR and related facilities in FY2014

Eguchi, Shohei; Takemoto, Noriyuki; Tanimoto, Masataka; Kubo, Ayako; Ishitsuka, Etsuo; Nakamura, Jinichi; Ito, Haruhiko

JAEA-Review 2015-005, 38 Pages, 2015/06

JAEA-Review-2015-005.pdf:15.06MB

Since fiscal 2011, a practical training course using the JMTR and other research infrastructures has been provided by Neutron Irradiation Testing Reactor Center for foreign young researchers and engineers in Asian and other countries which are planning to introduce power reactors. The aim of this course is to contribute to the human resource development in nuclear research field and to increase the future use the JMTR. On the other hand, a training course for Japanese young researchers and engineers has been conducted since fiscal 2010. In fiscal 2014, these two separate courses were integrated into one and it was conducted for 3 weeks for young researchers and engineers at home as well as abroad. Nineteen persons from seven countries participated and they studied about the general outline of nuclear research, current status and R&D of nuclear energy, irradiation test facilities and technologies, nuclear characteristics of the reactor and safety and operation management of nuclear reactors. At the end of the course, we had an active discussion about the current status and future of energy mix. The content of this training course in fiscal 2014 are reported in this paper.

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.

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.

Rapid collection of iron hydroxiedes for determination of Th isotopes in seawater using polyamin type chelating resin

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

no journal, , 

This work introduces a novel method of recovery of iron hydroxide with thorium 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 co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. The chelating column quantitatively collect Th with iron hydroxide in seawater at flow rate of 20-25 mL/min. Based on this flow rate, 5 L sample was processed within 3-4 h. The aging of iron hydroxide tends to reduce the recovery of Th. The rapid collection method was successfully applied to the determination of Th and Th in open-ocean seawater samples.

Age-dating of single particle of uranium standard material for nuclear forensics and safeguards

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.

Nuclear forensics and radiochemistry

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.