Results 1 - 10 of 501
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[en] Samples of materials involved in the conversion of uranium into nuclear-grade products are collected to support the verification of States' declarations and to look for indications of possible undeclared materials and activities. Samples are analysed by several laboratories to determine concentrations of about sixty impurities; the data consistency is addressed through the unified reporting requirements, the use of common reference materials, and via inter-laboratory comparisons. The impurity analysis results, along with other essential parameters, are interpreted to judge sample conformity to the relevant specifications, to evaluate the facility design information, to assess material provenance and intended use. (author)
[en] New techniques that could assist law enforcement officers in the evaluation of radioactive materials of unknown provenance are required. This paper provides preliminary results on a new method for iridium metal dissolution using pressure digestion vessels and hydrogen peroxide, which has been developed for use in forensic applications. The results were generated using iridium powder as a surrogate, but it is anticipated that the method will be directly transferable to iridium source materials. (author)
[en] Different approaches to interpretation of the same analytical results as well as of the same information are demonstrated. Examples of TTX “Glowing Tulip” as well as of one real investigation are considered. Possible reasons of different results of analysis of the same data are mentioned and discussed. (author)
[en] During the last years a coherent program started in IFIN-HH with the aim of establishing the first dedicated nuclear forensics laboratory in Romania. The steps taken in the implementation of this program are presented, with some results obtained our R&D activity. (author)
[en] The paper will discuss an array of TTX-based nuclear forensics training tools that are being used and developed, with a more thorough explanation of the Tabletop Cooperative Simulation Exercises (TCSE). Discussion will suggest guidelines and resources for preparing an exercise appropriate to training goals within a systematic approach. This work is intended to bolster international efforts to deliver nuclear forensics training offerings that are well characterized within best practices. (author)
[en] Forensic science seeks to predict source characteristics using measured observables. Statistically, this objective can be thought of as an inverse problem where interest is in the unknown source characteristics or factors (X) of some underlying causal model producing the observables or responses (Y = g (X) + error). Here, this paper reviews several statistical methods for use in inverse problems and demonstrates that comparing results from multiple methods can be used to assess predictive capability. Motivation for assessing inverse predictions comes from the desired application to historical and future experiments involving nuclear material production for forensics research in which inverse predictions, along with an assessment of predictive capability, are desired.
[en] The first nuclear bomb detonation on Earth involved a plutonium implosion-type device exploded at the Trinity test site (33°40'38.28N, 106°28'31.44W), White Sands Proving Grounds, near Alamogordo, New Mexico. Melting and subsequent quenching of the local arkosic sand produced glassy material, designated “Trinitite”. In cross section, Trinitite comprises a thin (1–2 mm), primarily glassy surface above a lower zone (1–2 cm) of mixed melt and mineral fragments from the precursor sand. Multiple hypotheses have been put forward to explain these well-documented but heterogeneous textures. In this study, we report the first quantitative textural analysis of vesicles in Trinitite to constrain their physical and thermal history. Vesicle morphology and size distributions confirm the upper, glassy surface records a distinct processing history from the lower region, that is useful in determining the original sample surface orientation. Specifically, the glassy layer has lower vesicle density, with larger sizes and more rounded population in cross-section. This vertical stratigraphy is attributed to a two-stage evolution of Trinitite glass from quench cooling of the upper layer followed by prolonged heating of the subsurface. Finally, defining the physical regime of post-melting processes constrains the potential for surface mixing and vesicle formation in a post-detonation environment.
[en] The paper will discuss the advancement of the science and state of practice of nuclear forensic analysis over the 20- year history of Nuclear Forensics International Technical Working Group (ITWG) Collaborative Materials Exercises (CMX). (author)