Isotopic, structural, and elemental characterization of uranium nuclear forensic samples within the 7th Collaborative Material Exercise

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F23%3A00366996" target="_blank" >RIV/68407700:21340/23:00366996 - isvavai.cz</a>

Result on the web

<a href="https://static.akcongress.com/downloads/ranc/ranc2023-boa.pdf" target="_blank" >https://static.akcongress.com/downloads/ranc/ranc2023-boa.pdf</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Isotopic, structural, and elemental characterization of uranium nuclear forensic samples within the 7th Collaborative Material Exercise

Original language description

This paper aims to describe the nuclear-forensic characterization of materials provided by the Nuclear forensic international technical working group (ITWG) within the 7th Collaborative Material Exercise (CMX-7). The characterized materials were two powdered uranium-compound samples labelled ES-1 and ES-3 and two uranium metal samples labelled ES-2 and ES-4. A combination of several analytical and radiometric techniques was used by a group of Czech laboratories to the identification of chemical compounds, the determination of the uranium isotopic composition and the elemental composition of all four samples. Those results allowed for an unambiguous conclusion that the ES-1 is depleted uranium trioxide, ES-2 is depleted uranium-vanadium alloy, ES-3 is depleted uranium nitrate, and ES-4 is depleted uranium metal. A further conclusion was that ES-2 cannot originate from the same source as the other three samples and that ES-1, ES-3, and ES-4 had a common source material. After excluding the ES-2 sample from the association with the other ones, the next task was the search for any other characteristics, besides the isotopics, linking the remaining three samples ES-1, ES-3, and ES-4 with each other through a chemical technological process. Though chemical reactions leading to the transformation of one sample into the other one (ES-4 uranium metal into ES-3 uranium nitrate powder and this powder into ES-1 uranium trioxide powder) could have been quickly proposed, the experimental proof at a high level of confidence turned out to be difficult to obtain. Available elemental screening methods of Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy (SEM-EDX) or Energy Dispersive X-Ray Fluorescence (EDXRF) did not provide conclusive results. Therefore, additional elemental survey method - Neutron Activation Analysis with pre-separation (PS-NAA) to remove uranium by extraction chromatography resin UTEVATM was used to obtain information about a possible linkage among ES-1, ES-3, and ES-4 samples. The use of the PS-NAA for trace-element screening provided concentrations of more than 10 elements at ppm levels for all four samples. The cluster analysis of the PS-NAA data revealed short linkage distance between the ES-4 metal and the ES-3 powder, which supported the conclusion that the uranium nitrate powder ES-3 was created from the uranium metal ES-4. The other powdered sample ES-1 had long linkage distance to both ES-3 and ES-4, therefore the proposed reaction path between the uranium nitrate powder and the uranium trioxide powder remained neither confirmed nor excluded. Though the potential of PS-NAA for survey analysis has not been fully explored in this work, it can be already concluded that PS-NAA could be a useful tool for trace level elemental screening of samples with high content of uranium and its application potential in nuclear forensics deserves further exploration.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

10402 - Inorganic and nuclear chemistry

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů