Browsing by Author "Keegan, EA"
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- ItemANSTO Nuclear Foresnics Research Facility: method development and applications(Australian Nuclear Science and Technology Organisation, 2012-10-16) Wotherspoon, ATL; Hill, DM; Keegan, EA; Evans, T; Blagojevic, N; Loi, E; Toole, K; Griffiths, GJ; Smith, KL; Reinhard, MIThe IAEA defines nuclear forensic science, commonly shortened to “nuclear forensics” as ‘the scientific analysis of nuclear or other radioactive material, or of other evidence that is contaminated with radioactive material, in the context of legal proceedings, including administrative, civil, criminal or international law’1. In broad terms, the job of the nuclear forensic scientist is to support investigations that involve a nuclear security event. Nuclear forensic examinations will provide information to key questions posed by the investigative authority: What is it? How much is there? Is there any more out there? Is it ours? As an investigation proceeds other questions that may arise are; How old is it? What contaminants are present? Does it pose a threat? Who is responsible for the loss? Where did the material come from? Many of the techniques required to answer these questions are based on environmental radiochemistry. The Nuclear Forensic Research Facility (NFRF) at ANSTO is developing expertise in analysing nuclear and other radioactive material material based upon the precepts of the ‘model action plan’ of the International Technical Working Group for Nuclear Forensics (ITWG) and other best practices. We are also investigating the validity of traditional forensic techniques (like fingerprints and DNA) on evidence contaminated with radioactive material alongside more novel parameters, e.g. the isotopic composition at the ‘bulk’ material and the micro scale using advanced micro-analytical techniques. We are moving towards the integration of a range of radio analytical techniques such as mass spectrometry, electron microscopy and the simulation/modelling of material production signatures, to provide a range of different information streams to assist attribution. With each advance in our technical competencies we enhance our means to ensure the security of nuclear or other radioactive material.
- ItemApplication of lead and strontium isotope ratio measurements for the origin assessment of uranium ore concentrates(American Chemical Society, 2009-10-15) Varga, Z; Wallenius, M; Mayer, K; Keegan, EA; Millett, SLead and strontium isotope ratios were used for the origin assessment of uranium ore concentrates (yellow cakes) for nuclear forensic purposes. A simple and low-background sample preparation method was developed for the simultaneous separation of the analytes followed by the measurement of the isotope ratios by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The lead isotopic composition of the ore concentrates suggests applicability for the verification of the source of the nuclear material and by the use of the radiogenic 207Pb/206Pb ratio the age of the raw ore material can be calculated. However, during data interpretation, the relatively high variation of the lead isotopic composition within the mine site and the generally high contribution of natural lead as technological contamination have to be carefully taken into account. The 87Sr/86Sr isotope ratio is less prone to the variation within one mine site and less affected by the production process, thus it was found to be a more purposeful indicator for the origin assessment and source verification than the lead. The lead and strontium isotope ratios measured and the methodology developed provide information on the initial raw uranium ore used, and thus they can be used for source attribution of the uranium ore concentrates. © 2009, American Chemical Society
- ItemThe application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)(Springer Nature, 2018-02-06) Kristo, MJ; Williams, R; Gaffney, AM; Kayzar-Boggs, TM; Schorzman, KC; Lagerkvist, P; Vesterlund, A; Ramebäck, H; Nelwamondo, AN; Kotze, D; Song, K; Lim, SH; Han, SH; Lee, CG; Okubo, A; Maloubier, D; Cardona, D; Samuleev, P; Dimayuga, I; Varga, Z; Wallenius, M; Mayer, K; Loi, E; Keegan, EA; Harrison, JJ; Thiruvoth, S; Stanley, FE; Spencer, KJ; Tandon, LIn 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 235U–231Pa and 234U–230Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions. © 2018 U.S. Government
- ItemNuclear forensic analysis of an unknown uranium ore concentrate sample seized in a criminal investigation in Australia(Elsevier, 2014-07) Keegan, EA; Kristo, MJ; Colella, M; Robel, M; Williams, R; Lindvall, R; Eppich, G; Roberts, SK; Borg, L; Gaffney, AM; Plaue, J; Wong, HKY; Davis, J; Loi, E; Reinhard, MI; Hutcheon, IEarly in 2009, a state policing agency raided a clandestine drug laboratory in a suburb of a major city in Australia. During the search of the laboratory, a small glass jar labelled “Gamma Source” and containing a green powder was discovered. The powder was radioactive. This paper documents the detailed nuclear forensic analysis undertaken to characterise and identify the material and determine its provenance. Isotopic and impurity content, phase composition, microstructure and other characteristics were measured on the seized sample, and the results were compared with similar material obtained from the suspected source (ore and ore concentrate material). While an extensive range of parameters were measured, the key ‘nuclear forensic signatures’ used to identify the material were the U isotopic composition, Pb and Sr isotope ratios, and the rare earth element pattern. These measurements, in combination with statistical analysis of the elemental and isotopic content of the material against a database of uranium ore concentrates sourced from mines located worldwide, led to the conclusion that the seized material (a uranium ore concentrate of natural isotopic abundance) most likely originated from Mary Kathleen, a former Australian uranium mine. © 2014 Elsevier Ireland Ltd.
- ItemNuclear forensics: scientific analysis supporting law enforcement and nuclear security investigations(American Chemical Society, 2015-12-24) Keegan, EA; Kristo, MJ; Toole, K; Kips, R; Young, ELNuclear forensic science, or "nuclear forensic", aims to answer questions about nuclear material found outside of regulatory control. In this Feature, we provide a general overview of nuclear forensics, selecting examples of key "nuclear forensic signatures" which have allowed investigators to determine the identity of unknown nuclear material in real investigations. © 2015 American Chemical Society
- ItemPhase analysis of Australian uranium ore concentrates determined by variable temperature synchrotron powder x-ray diffraction(American Chemical Society, 2021-07-22) Pandelus, SB; Kennedy, BJ; Murphy, GL; Brand, HEA; Keegan, EA; Pring, A; Popelka-Filcoff, RSThe chemical speciation of uranium oxides is sensitive to the provenance of the samples and their storage conditions. Here, we use diffraction methods to characterize the phases found in three aged (>10 years) uranium ore concentrates of different origins as well as in situ analysis of the thermally induced structural transitions of these materials. The structures of the crystalline phases found in the three samples have been refined, using high-resolution synchrotron X-ray diffraction data. Rietveld analysis of the samples from the Olympic Dam and Ranger uranium mines has revealed the presence of crystalline α-UO2(OH)2, together with metaschoepite (UO2)4O(OH)6·5H2O, in the aged U3O8 samples, and it is speculated that this forms as a consequence of the corrosion of U3O8 in the presence of metaschoepite. The third sample, from the Beverley uranium mine, contains the peroxide [UO2(η2-O2)(H2O)2] (metastudtite) together with α-UO2(OH)2 and metaschoepite. A core–shell model is proposed to account for the broadening of the diffraction peaks of the U3O8 evident in the samples. © 2021 American Chemical Society
- ItemThe provenance of Australian uranium ore concentrates by elemental and isotopic analysis(Elsevier, 2008-04) Keegan, EA; Richter, S; Kelly, I; Wong, HKY; Gadd, PS; Kuehn, H; Alonso-Munoz, AElemental and isotopic ratio analyses of U ore concentrate samples, from the 3 operating U mining facilities in Australia, were carried out to determine if significant variations exist between their products, thereby allowing the U ore concentrate's origin to be identified. Elemental analyses were conducted using inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF). Lead isotope ratios were measured using ICP-MS and U isotope analyses were conducted using thermal ionisation mass spectrometry (TIMS). Minute quantities of sample, such as that obtained from a swipe, were also examined for elemental concentrations using secondary ion mass spectrometry (SIMS). The results of multivariate statistical analysis show clear patterns in the trace elemental composition of the processed U ores, indicating that it is possible to use this feature as a unique identifier of an Australian U ore concentrate's source. Secondary ion mass spectrometry analyses also allow individual particles to be differentiated using this 'fingerprinting' technique. Isotope ratios determined using TIMS reveal that there is a significant difference in the n(U-234)/n(U-238) isotope ratio between the U ore concentrate from each mine. © 2007, Elsevier Ltd.
- ItemUOC characterisation and 231Pa based isotope chronometer development for application in nuclear forensics(Australian Nuclear Science and Technology Organisation, 2012-10-17) Keegan, EAWhile environmental sampling is a well established nuclear safeguards tool, the information contained in measurements performed on radioactive environmental samples may also be of use for nuclear forensic purposes. Nuclear forensics (NF) is the scientific analysis of nuclear or radioactive material, or of evidence that is contaminated with radioactive material, in the context of legal proceedings [1]. Piecing together collected evidence, for instance in the case of a detonated radiological dispersal device (RDD), may provide clues as to the provenance of the material involved in such nuclear security events. Research in this area involves profile analysis on radioactive or nuclear materials and debris identifying parameters, such as isotopic composition, which constitute a unique ‘signature’ of the material, potentially leading to attribution. This paper will outline the research activities of ANSTO’s recently established Nuclear Forensic Research Facility (NFRF) and its endeavors in performing measurements on environmental samples within the context of nuclear forensics. For instance, uranium mining and milling are a potential source of contamination of the environment with radioactive material. Work carried out by the NFRF has demonstrated that even particle sized samples of uranium ore concentrate (UOC) can be tracked back to the mine from which it originated. New analytical capabilities within NFRF will be presented and discussed. For example, the 231Pa/235U isotope chronometer while being developed for NF purposes can also be readily applied to environmental monitoring.