[en] The first nuclear bomb detonation on Earth involved a plutonium implosion-type device exploded at the Trinity test site (33°40'38.28^N, 106°28'31.44^W), 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.

No abstract available

[en] The need for joint investigations of seized radioactive samples by both NRM specialists and forensic experts, who study these samples using traditional forensic techniques is no longer in doubt. However, the most significant steps in identifying the problems arising from the interaction of specialists from different scientific schools and different departments, in finding ways to solve these problems, can be made in the process and during recognizing the results of the exercises. This understanding has been reflected in exercises organized by the International Technical Working Group on Nuclear Forensics [1], as well as in the recent IAEA regional nuclear forensics exercises for the CIS and Eastern Europe countries. It should also be noted that the need for coordinated actions by these specialists, as well as investigators, arises before the start of samples analyses in laboratories. It arises at the crime scene. Therefore the main goal of the exercise in 2021 was to develop the interaction of investigators, forensic experts and NRM specialists at different stages of a crime investigation.

[en] International nuclear forensics documents can play a significant role in helping countries in developing as well as in maintaining stable national nuclear forensics capabilities. These documents can accumulate whole experience, gained by different countries in solving problems that arise in both: in setting analytical tasks and in analyzing NRM samples or samples contaminated with trace amounts of NRM. International recommendations for the development and maintenance of stable nuclear forensic capabilities may have two directions: • Proposals for the organization and improvement of the national system for identification of NRM, detected outside regulatory control; • Recommendations for performing analyses of samples in the framework of forensic examination of physical evidence. Proposals for the organization and improvement of the national system should be developed by a team of specialists in different fields and from different countries. The team of authors should include representatives of law enforcement agencies: experts in the field of legislation, as well as practitioners conducting criminal investigations, and both kinds of analysts: experts in the field of nuclear forensic examinations as well as experts in traditional forensic techniques. Moreover, if the document under development concerns practical recommendations on interaction with courts, than countries with different judicial systems and with different rules and traditions of law enforcement agencies should be represented in the team. If the recommendations contain proposals for structural changes in existing national services and organizations, these recommendations should be discussed with representatives of such services and organizations from different countries. These proposals should have clear purposes and contain only carefully verified definitions, basic concepts and approaches. These definitions, concepts and approaches must comply with the definitions, basic concepts and approaches developed and adopted in other areas of forensic science, and should not contradict the culture of the forensic community.

[en] Participatory simulation exercises build on the foundation of advanced practitioners’ nuclear detection knowledge and experience. They aim to promote the harmonization and exchange of good practices amongst experts. The exercises simulate work situations and environment at the table top level, and can be designed to focus on interaction between organizations with different but linked nuclear security functions within one state, or from different states. In this way, simulation exercises can be designed to focus on both internal (i.e., Front Line Officers and Technical Support) and external (i.e., bilateral/regional/international) communications. This exercise methodology thus involves teaming individuals who in their day-to-day job responsibilities perform similar tasks and challenges them with realistic practical scenarios. The success of the simulation exercise is grounded during the development cycle, where a master team including subject matter experts from the disciplines and countries participating in the exercise cooperatively develop scenario and inject elements. The resulting element of realism and regional appropriateness creates an environment conducive to engagement of the participants with the exercise, and, concomitantly, the exchange of ideas and established practices in different fields involved in the practice of nuclear security. Past iterations include SimEX (2015) and IASE (2016), which emphasized export control; COSINUS I (2016, Southeast Asia) and II (2018, Central Asia) which focused on nuclear security; and NUFORSE 2017 for nuclear forensics.

[en] The Nuclear Forensics International Technical Working Group (ITWG) recently completed its sixth Collaborative Materials Exercise (CMX-6) – Operation Celestial Skónis. This latest CMX also represented the largest exercise on record in the 25-year history of the ITWG and included participation by 22 laboratories and 15 law enforcement (LE) agencies from 21 countries and one multinational organization. Celestial Skónis was a paired-comparison exercise, in which more than one sample is distributed to participating laboratories for comparison purposes. As is customary with past CMXs, laboratories participating in Celestial Skónis were asked to analyze nuclear and radiological materials as part of a mock nuclear forensic investigation. However, participants of Celestial Skónis were also asked to examine contaminated and radioactive items for conventional forensic evidence (e.g., fingerprints, toolmarks, etc) – an activity that had only been incorporated once before during CMX-2 (2001). A primary outcome of CMXs, participants identify and share best practices in nuclear forensic science during the Data Review Meeting following the exercise.

[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 presentation focuses on pre- and post-detonation nuclear forensics and the various roles it plays.

[en] 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. Each of the laboratories had their strategic role to play in its respective country, analyzing real-world samples using their in-house resources. The scenario was fictitious but was thoughtfully crafted to engage participants in nuclear forensic investigations. In this paper, participants from five of the first-time laboratories shared their individual experience in this exercise, from preparation to analysis of samples. (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)