Journal Article

FZJ-2026-04542

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Synthesis and characterisation of thorium-doped uranium oxide microparticles for nuclear safeguards-relevant dating

Hertwig, A. T. (Corresponding author) ; Kegler, P.FZJ* ; Sun, X. ; Saxey, D. W. ; Sadekov, A. ; Rickard, W. D. ; Schmitt, A. K. ; Neumeier, S.FZJ*

2026
ChemSoc Cambridge

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Please use a persistent id in citations: doi:10.1039/d6ja00326e

Abstract: 230Th/234U chronometry on micro-scale particles is an emerging capability in nuclear safeguards that enables verification of past and present activities at nuclear facilities for consistency with national and international declarations. The implementation of 230Th/234U chronometry by large-geometry secondary ion mass spectrometry (LG-SIMS) requires well-characterised reference materials to quantify inter-element fractionation (Th/U relative sensitivity factor, RSF) at relevant abundance levels. Here, we employ aerosol-based particle synthesis using a modified vibrating orifice aerosol generator (VOAG) setup to synthesise three products of monodisperse uranium oxide microparticles from CRM 129-A starting solution (natural uranium isotopic composition): (1) an undoped blank product, (2) a 232Th-doped product at 232Th/238U = 0.001 (atomic) for direct RSF calibration, and (3) a low-level 230Th-doped product at 230Th/238U = 0.3 × 10−6 (atomic) designed to yield an apparent model age of 2025 years (equivalent to the year 1 CE) in the CRM 129-A matrix. The targeted 230Th abundance per particle corresponds to practically relevant 230Th contents encountered during 230Th/234U dating of enriched uranium particles. Particle morphology and structure were assessed by focused ion beam scanning electron microscopy (FIB-SEM) and Raman microspectroscopy, while thorium distribution and content of individual particles were evaluated by atom probe tomography (APT) and LG-SIMS analysis. Solution inductively coupled plasma mass spectrometry (ICP-MS) provided independent 232Th quantification, confirming dopant levels. The results demonstrate homogeneous thorium incorporation at the sub-micrometre scale and across particles of the 232Th-doped product and verify the targeted 230Th concentration of the model-age control product. Overall, the results establish VOAG synthesis as a viable route for generating reference microparticles that support Th/U RSF calibration and 230Th/234U enrichment dating near the limit of detectability.

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Contributing Institute(s):

1. Nukleare Entsorgung (IFN-2)

Research Program(s):

1. 1412 - Predisposal (POF4-141) (POF4-141)

Appears in the scientific report 2026

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Database coverage:
; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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