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Abstract  

Delayed neutron activation analysis (DNAA) presents a fast, accurate, and reliable method for quantification of fissile material. The method has relatively few sources of error and may be accomplished nondestructively. The need for a fast, accurate screening of materials stems from the necessity to protect cleanroom facilities from widely varying fissile quantities in samples and from desired gains in efficiency of mass spectrometric analysis by assisting in spike level selection and by removing from the sample set those materials that are not of interest. During the last several years, many different materials have been screened or analyzed in support of international safeguards, internal process control for actinide separations, and in uranium contamination assessments. Swipes from a variety of sources have been analyzed, either before or after dissolution, and comparison of the DNAA results to mass spectrometry results is generally favorable. A facility characterization of the High Flux Isotope Reactor was performed using filter paper swipes to demonstrate the utility of the DNAA technique.

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Abstract  

Recent attention to international safeguards has stimulated interest in nondestructive analysis techniques. These NDA techniques include high- and low-resolution gamma-ray spectrometry, active and passive neutron counting, and physical measurements. Often, the NDA measurements are made abroad under field conditions, and in these cases, portability is important. In other cases, the measurements are made under laboratory conditions but no calibration materials are available. This paper describes several NDA applications in support of international safeguards projects, all involving international cooperation.

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Abstract  

We are developing superconducting ultrahigh resolution gamma-detectors for non-destructive analysis (NDA) of nuclear materials, and specifically for spent fuel characterization in nuclear safeguards. The detectors offer an energy resolution below 100 eV FWHM at 100 keV, and can therefore significantly increase the precision of NDA at low energies where line overlap affects the errors of the measurement when using germanium detectors. They also increase the peak-to-background ratio and thus improve the detection limits for weak gamma emissions from the fissile Pu and U isotopes at low energy in the presence of an intense Compton background from the fission products in spent fuel. Here we demonstrate high energy resolution and high peak-to-background ratio of our superconducting Gamma detectors, and discuss their relevance for measuring actinides in spent nuclear fuel.

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Abstract  

An improved method of fission track (FT) sample preparation was developed, in which the detector of fission track and the layer containing particles are separated, in order to apply the FT-thermal ionization mass spectrometry (TIMS) for particle analysis of safeguards environmental samples. The developed FT sample enabled us to detect the particle of interest simply by observing the fission tracks. The process of particle identification was difficult due to the discrepancy between the position of the particles and fission tracks, which were observed in the conventional FT sample. The proposed method has significantly resolved this problem.

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Summary  

The use of environmental monitoring as a technique to identify activities related to the nuclear fuel cycle has been proposed by international safeguards organizations. The elements specific for each kind of nuclear activity, or “nuclear signatures”, inserted in the ecosystem can be intercepted by different live organisms. This work demonstrates the technical viability of using pine needles as bioindicators of nuclear signatures associated with uranium enrichment activities. Additionally, it proposes the use of HR-ICP-MS to identify the signature corresponding to that kind of activities in the ecosystem. Nitric acid solutions, used to wash pine needles sampled near nuclear facilities and containing only 0.1 mg . kg-1 of uranium, exhibit a n(235U)/n(238U) isotopic abundance ratio of 0.0092±0.0002, while solutions originated from samples collected at places located more than 200 km far from activities related to the nuclear fuel cycle exhibit a value of 0.0074±0.0002. Similar results were obtained for sample solutions prepared using the acid leaching process. The different values of n(235U)/n(238U) isotopic abundance ratio obtained permit to confirm the presence of anthropogenic uranium and demonstrate the viability of using the methodology proposed in this work.

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Abstract  

Environmental sampling (ES) is one of the measures applied in international nuclear safeguards. The detection capability of safeguards ES relies on a combination of highly sensitive analytical techniques and resourceful data evaluation. The evaluation process is dynamic, employing a variety of tools, information and analytical results. While the presence of uranium or plutonium may be a significant finding in itself, high quality isotopic measurements are essential to associate the material with a specific nuclear activity. This is illustrated in cases where the uranium detected appears to be “natural” or “near-natural”, but in fact can be identified with various nuclear processes.

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Transmission in the AMDA Group . [video online] Available at: http://youtu.be/NjtTn1OfA2o [Accessed: 30 Dec 2013]. A wuah , E. B. 2013b : A Study of Amateur Groups’ Re-Interpretation of Traditional Dances in Ghana: Role on Continuity and Safeguarding

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Abstract  

The purpose of this study was twofold: the identification of some uranium compounds and a measurement of mixed U/Pu particles with different ratios of these elements. We used a Philips XL-30 scanning electron microscope equipped with an EDAX energy dispersive spectrometer with a Si(Li) detector and a super ultra-thin polymer window and with a Microspec wavelength dispersive spectrometer. A number of WDXRF and EDXRF spectra of U and Pu containing particles were accumulated and evaluated. The software package provided by the manufacturer was used for EDXRF spectra evaluation and calculation of the weight and atomic composition. Eight different U compounds were identified with a different degree of confidence. Several different types of U and Pu particles were measured using the WDXRF spectrometer and the results of the measurements are discussed. The measurement of mixed U-Pu particles showing large differences in the concentration of both elements can best be carried out with the use of WDXRF because the deconvolution of the M lines of U and Pu in the energy dispersive spectra is only possible over a relatively small concentration range. The results of particle analysis are very useful for verifying the absence of undeclared nuclear activities.

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Abstract  

A method for the separation and determination of total and isotopic uranium and plutonium by ICP/MS was developed for IAEA samples on cellulose-based media. Preparation of the IAEA samples involved a series of redox chemistries and separations using TRU® resin (Eichrom). The sample introduction system, an APEX nebulizer (Elemental Scientific, Inc.), provided enhanced nebulization for a several-fold increase in sensitivity and reduction in background. Application of mass bias (ALPHA) correction factors greatly improved the precision of the data. By combining the enhancements of chemical separation, instrumentation and data processing, detection levels for uranium and plutonium approached high attogram levels.

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