Remote detection of alpha emitters is achieved by measuring the secondary radioluminescence light (air fluorescence) that is induced by alpha particles when absorbed in air. A telescope was used to ...collect the radioluminescence photons to a photomultiplier tube, which is operated in the photon counting mode. Careful matching of photocathode response and filter pass-band allows the sensing of a faint radioluminescence emission in a brightly illuminated environment, which is essential for operative use. A minimum detectable alpha activity of 4 kBq was reached at 1 m distance in 10 s time, when ultraviolet-free lighting is present, and 800 kBq under bright fluorescent lighting. These sensitivities are realized using an ultra-bialkali and cesium-telluride photocathodes in the aforementioned environments respectively. The presented approach is a robust and affordable solution to remotely detect and localize moderate alpha activities in a field environment, providing a means for automated alpha contamination mapping. Moreover, it is shown that a signal increase of more than two orders of magnitude (150-420) can be achieved in deep ultraviolet (close to 260 nm), if nitrogen or argon purge are used to enhance the detection.
A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma ...sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU™ resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg
g
−1 range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology.
The aim of the present work was to develop a direct method for age dating (production date measurement) of uranium samples by laser ablation multi-collector inductively coupled plasma mass ...spectrometry (LA-MC-ICP-MS) by the measurement of the
230
Th/
234
U ratio. The major instrumental conditions and sample characteristics affecting the accuracy and precision were investigated in this systematic study. By comparing the obtained LA-MC-ICP-MS results with those obtained after chemical separation measurements, it shows that the LA-MC-ICP-MS method is capable to produce accurate results for pure highly enriched uranium. Natural and low-enriched uranium, however, needs a higher mass resolution to remove the identified interferences, which can lead to erroneous results.
Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was used to study the heterogeneity of solid uranium materials. Using spatially resolved isotope ratio ...measurement, the degree of isotopic homogeneity at micron-level could be assessed in nuclear samples for nuclear safeguards and forensics purposes. LA-MC-ICP-MS was applied for two UO2 pellets which had been distributed in the 5th Collaborative Materials Exercise (CMX-5) organized by the Nuclear Forensics International Technical Working Group (ITWG). The two materials in question have very similar 235U isotope abundance (around 1%), but very different 235U isotopic heterogeneity. Although both UO2 pellets were prepared from identical source materials (mixture of depleted 0.3% and low-enriched 4.3% 235U), their different production routes resulted in observable differences at micron-scale. By the spatially resolved measurement the number of constituting components (feed materials) with different uranium enrichment and their n(234U)/n(238U) and n(235U)/n(238U) isotope ratios could be determined. Imaging can help assess the lateral dimensions of the individual components (grains) and may indicate a certain production route. This information on the inhomogeneity, the possible inference on the production process and isotopic composition of the constituents are highly valuable in nuclear forensics investigations for determining the origin of an unknown nuclear material.
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•Spatial inhomogeneity in U materials for nuclear forensics was studied by LA-MC-ICP-MS.•It can distinguish heterogeneous samples with same bulk 235U enrichment at micron-level.•The number of the starting materials and respective U enrichment can be determined.•2D-imaging of nuclear forensic materials was developed.
The present work describes a method for the preparation and validation of plutonium age dating reference materials. The test samples prepared in this context could be used to validate experimental ...protocols for determining the production date of plutonium via the 234U/238Pu, 235U/239Pu, 236U/240Pu, and 241Am/241Pu chronometers. The starting material was prepared using reactor-grade plutonium, which was purified using a dedicated method to guarantee high Pu recovery, while maximizing U and Am separation efficiencies. The U and Am separation factors were determined by the addition of high-amounts of 233U and 243Am spikes and their remeasurement in the final product. The prepared material is intended for quality control and assessment of method performance in nuclear forensics and safeguards.
Employing laser ablation multi-collector ICP-MS (LA-MC-ICP-MS), its potential for evaluating the homogeneity of solid uranium (U) bearing materials was investigated. To this end, the n(235U)/n(238U) ...ratio of two low-enriched U certified reference materials (CRMs), i.e. powdered standard reference material U-010 (~1wt% 235U) and a UO2 pellet of CRM 125-A (~4wt% 235U) was determined using line scan analysis. Four spots of 5μm diameter each were ablated per second with the LA system moved at a speed of 20μms−1 for several minutes. Experimental and certified U isotope ratios matched perfectly, unequivocally validating the accuracy of the applied analytical methodology. In addition, the narrow and symmetric frequency distribution of the n(235U)/n(238U) ratio of both CRMs confirmed their homogeneity with respect to the U isotopic composition. Utilizing LA-MC-ICP-MS line scan analysis of two similar UO2 pellets (~1wt% 235U) from the 5th Collaborative Materials Exercise (CMX-5) revealed diverse inhomogeneity regarding their n(235U)/n(238U) ratio. Although both UO2 pellets used for the CMX-5 exercise were prepared from identical source materials, their different production routes yielded largely contrasting frequency distributions of the n(235U)/n(238U) ratio. While 235U isotope abundance ranged from 0.75%–1.6% for the first pellet, this value fluctuated between 0.45% and 3.0% for the second pellet. This specific information sheds additional light on the production process of these materials and is helpful in nuclear forensics investigations when determining the origin of unknown nuclear material. The depleted nature (~0.4wt% 235U) of two seized U metal samples was established through LA-MC-ICP-MS analysis of the n(235U)/n(238U) ratio. As black and yellow regions within both U bearing samples had identical U isotopic composition, the observed colour differences might arise from different degrees of U oxidation and are not associated with U isotopic inhomogeneity within the material. The significantly different 235U abundance of the two samples (0.3670±0.0015 wt.% and 0.4146±0.0013 wt.%), however, clearly indicates they were prepared from different source materials and/or from diverse amounts of them.
•Accurate and precise n(235U)/n(238U) ratios are obtained for U bearing materials employing LA-MC-ICP-MS.•Excellent agreement of U isotope ratios between laser-based and solution-based MC-ICP-MS analysis as well as certified values.•Using line scan analysis, the U isotopic (micro-)homogeneity of solid UO2 pellets can be assessed quickly.•Two UO2 pellets prepared from identical source materials had diverse distribution of their U isotopic composition.•Differently coloured regions within samples revealed identical U isotopic composition reflecting diverse oxidation states of U.
Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was applied to the detailed investigation of the uranium (U) isotopic composition (
234
U,
235
U,
236
U, and
...238
U) of five contaminated scrap metal samples found within the European Union. Pressed pellets of the two certified U isotopic reference materials CRM U-020 and CRM U-030 were included in the measurement protocol for mass bias correction, calculation of the ion counter gains and for quality assurance. Since the investigated samples had low U content (0.15-14.3 wt%) compared to typically analysed pure U compounds (>60 wt%), the applied experimental parameters had to be adjusted. Spatially-resolved U isotopic information was obtained by line scan analysis of each sample. While other analytical techniques used typically in nuclear forensic investigations, such as γ-spectrometry and thermal ionisation mass spectrometry (TIMS) yielded average U isotopic compositions of the entire sample, LA-MC-ICP-MS provided substantial added value, highlighting the inhomogeneous distribution of U isotopes within various scrap metal samples. Analysis of individual particles
via
secondary ion mass spectrometry (SIMS) confirmed the large range of
235
U enrichment levels in heterogeneous scrap metal samples. Four out of five scrap metal samples contained
236
U (∼0.05-∼0.11 wt%), indicating the presence of reprocessed U. Taken together, LA-MC-ICP-MS analysis provided fast and accurate spatially-resolved U isotopic information without consuming or altering the scrap metal samples, a key feature for nuclear forensics investigations.
LA-MC-ICP-MS is a fast and quasi non-destructive technique to reveal possible U isotopic inhomogeneity in scrap metal samples, filling the gap between bulk isotopic analysis and particle analysis.
A reliable and accurate laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) method was developed for analysis of inhomogeneous samples containing uranium ...particles or aggregates of various enrichments. For the method development, a mixed solid standard was prepared using 1% and 3%
235
U enriched certified reference materials. After screening and localization of the particles of interest, the U isotopic composition was analysed for a 5-µm sample spot determining accurately and precisely the various constituents. Besides the LA-MC-ICP-MS, the standard was also measured by large-geometry secondary ion mass spectrometry (LG-SIMS) for additional verification.
In this work, the resin capacity factors of Ac, Am and Th on the DGA extraction chromatographic resin have been investigated between 0.5 and 2.0 M nitric acid without and with addition of elevated ...concentrations of the selective tetravalent complexant, 343HOPO. The resin capacity factors decreased with increasing 343HOPO concentration but remained high enough to support a selective removal of a tetravalent element. The Ac and Am capacity factors were also investigated under Th loading which yields generally reduced uptake on the resin. It was shown that loading effects could be fully scavenged by the addition of 343HOPO complexant. These results indicate that separation steps for Ac involving significant amounts of Th can be handled by selective tetravalent complexation with the DGA system.
In the framework of the European Commission Support Programme to the International Atomic Energy Agency (EC SP task A1753) 20 samples were obtained from the Dolní Rožínka (DIAMO, Czech Republic) ...uranium milling facility. The sampling procedure followed stepwise the uranium production and purification from the U ore to uranium ore concentrate (yellow cake) end-product. Elemental concentrations, rare-earth elemental pattern, anion concentrations, morphology and isotope abundance ratios of S, Sr, Pb and U were measured at each sampling stage. The purpose of the measurements was to investigate the applicability of various material characteristics for authentication, propagation and variation of these parameters, and to identify the relevant signatures for nuclear forensics and safeguards during the uranium production.
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