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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Jakopič, A. Verbruggen, R. Eykens, F. Kehoe, H. Kühn, Y. Kushigeta, U. Jacobsson, J. Bauwens, S. Richter, R. Wellum, and Y. Aregbe

Abstract  

In nuclear safeguards, precise and accurate isotopic analyses are needed for two major elements from the nuclear fuel cycle: uranium and plutonium. This can be achieved by Isotope Dilution Mass Spectrometry (IDMS), which is one of the most reliable analytical techniques for the determination of plutonium amount content to a high level of accuracy. In order to achieve reliable isotope measurements isotopic reference materials with certified amount of plutonium and isotopic composition are required. At the Institute for Reference Materials and Measurements (IRMM) various plutonium spike reference materials for isotopes 239Pu, 240Pu, 242Pu and 244Pu are available. This enabled the setup of an inter-calibration campaign inter-linking selected plutonium spikes on a metrological basis applying state-of-the-art measurement procedures. The aim of this campaign is threefold: firstly to perform measurements on selected plutonium spike isotopic reference materials for quality control purposes, secondly to verify the amount content and the isotopic composition of the recently produced IRMM-1027m large sized dried (LSD) spikes and thirdly to demonstrate IRMM’s measurement capabilities for plutonium analysis via external quality tools. The obtained results using various spike isotopic reference materials will be presented and discussed in this paper. The measurement uncertainties of the IDMS results were calculated according to the guide to the expression of uncertainty in measurement (GUM).

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Abstract  

A computer program entitled SCAAP (Set-up, Calibration, Acquisition and Analysis Program) has been designed to make gamma-ray spectroscopy easily useable by staff in laboratories at the Slowpoke-2 Facility at RMC and in support of the Canadian Forces Nuclear Emergency Response Teams (NERTs). The former group utilises gamma-ray spectroscopy for neutron activation analysis (NAA), while the latter may need to have inhalation dose rates calculated. The intent of this program, written using Microsoft Visual Basic, is to provide a simplified interface between the operator and the spectroscopy equipment and to provide the calculations necessary to produce results quickly. There are five sections (Setup, Calibrate, Acquire, Analyse and NAA) of which the first four are linked. In these sections, a checklist of procedures is presented and automated for the user to set up and calibrate the equipment and then to analyse spectra to provide various dose rates. In the unlinked section, NAA, gamma-ray spectra are analysed to provide elemental concentrations in samples.

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Abstract  

The activity of -emitting radionuclides is usually measured by semiconductor detectors (surface barrier or ion implanted). Overlapping and composite bands are quite common problems depending on energy differences of the radionuclides and counting source preparation. The classical approach to activity quantification is based on peak integration and, when it is used, overlapping may be overcome by a detailed study of each case, whereas composite bands can not be completely resolved. Here, spectra of the -emitting plutonium isotopes, obtained by ion implanted semiconductor detectors, have been used to compare the classical approach with a multivariate calibration method (MVC-PLS). The study is performed at environmental activity levels (0–52 dpm). The relative errors obtained for239+240Pu activity determination, using either the classical or the MVC-PLS approach with replicates, are good enough to quantify isotopes at low level activities. The distribution of relative errors is asymmetric, with a positive component for 0–10.5 dpm subset, in the classical approach whereas it is more symmetric in the MVC-PLS method. The results show that the classical approach depends on peak overlap, whereas the MVC does not. As a whole, MVC is a more robust method than the classical approach. Composite bands were studied using the239Pu–240Pu mixture; the MVC approach did not allow individual quantification due to the lack of signal reproducibility. This instability does not affect the regular integration procedures but it is important in the deconvolution processes. The lack of reproducibility is related to the source preparation process.

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Sixty left sides of pig carcasses were scanned by spiral computed tomography (CT) to measure lean meat weight and percentage. The carcasses were fully dissected and scanned to develop a calibration protocol. Different image analyses were performed on the basis of anatomically defined scans, direct volumetric estimation, body- and grey-scale ranges and using Partial Least Squares (PLS) regression of data provided by CT. The R2values of the calibrations for lean meat weight were 0.874, 0.976, 0.983 and 0.992, respectively, depending on the method applied. The PLS proved to be the best approach with a calibration RSD of 232 g. When changing from lean meat weight to percentage, the statistical goodness drops to a very small extent (R2= 0.988, RSD = 0.56). According to the results, the CT method can be recommended as a reference for determining the lean meat content of pig carcasses.

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Abstract  

In this paper, the setup, calibration, and testing of the F-Area Analytical Labs active well neutron coincidence counter (HV-221000-NDA-X-1-DK-AWCC-1) in SRNL are described for use in the Savannah River Site (SRS) transuranium metal production facility to enable assay of mixed uranium/plutonium metal product. The instrument was required within a three-month window for availability upon receipt of LANL uranium oxide samples into the SRS facility. Calibration of the instrument in the SRNL nuclear nondestructive assay facility in the range 10–400 g HEU is described. We also report qualification and installation of the instrument for assay of the initial suite of product samples.

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Abstract  

Thermoanalytical instruments are extensively used in R&D as well as in industrial quality control. A quantitative analysis of the data of a thermoanalytical measurement requires a careful calibration of the instrument. In differential scanning calorimetry (DSC) the quantities that have to be calibrated are the temperature and the heat flow. These two quantities are usually calibrated by evaluating melting or solid-solid transitions of some reference materials with well known transition enthalpies and temperatures. In this contribution we investigate temperature and heat flow calibration in the temperature range between −100 and 160C. We included 9 different samples for the analysis and established some general rules for the calibration process. As a result we found that with a well calibrated instrument the heat flow can be measured with 90% confidence to about 3% accuracy in this temperature range. With respect to temperature calibration we find that accuracies of 0.8C (90% confidence) may be expected. These values represent general accuracy limitations of DSC’s due to varying heat transfer conditions within the samples.

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Abstract  

A new Compton suppression system (CSS) for the gamma-ray spectrometer portion of the neutron activation analysis (NAA) was set up at the RPI/ITN. The pneumatic transfer system, SIPRA, for short-lived nuclides and cyclic irradiations was improved. A full calibration procedure of the CSS and SIPRA systems was performed. Two certified reference materials, NIST-SRM-1572 (Citrus Leaves) and NIST-SRM-1633a (Coal Fly Ash) were analyzed using the calibration factors. The CSS was instrumental in lowering the detection limits of Cr, Fe, Hg, Rb, Sr, Th and Zn by reducing background and/or spectral interference considerably. The analytical results were evaluated by comparison to the NIST certified values with deviations ranging from 2% to 8% for the above mentioned elements, except Zn ranging from 10% to 15% for biological and environmental samples, respectively.

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SPECT studies are sensitive but inaccurate means through which to analyze small volumes such as, for instance, remnant tissues after thyroidectomy. We studied the relation between known volumes (0.1–10 cm3) and volumes measured with SPECT studies and using solutions of four different isotopes: 99mTc, 117mSn, 111In, 131I. The curves we determined were tested on SPECT images of two patients treated with 131I. Our work suggests the possibility to evaluate the small remnant mass using calibration curves specific to the system of image acquisition. However, it is necessary to extend the study to a larger number of patients.

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Abstract  

Simultaneous measurement of gross alpha and gross beta activities by liquid scintillation counting technique using LKB Wallac Quantulus 1220 liquid scintillation counter (LSC) equipped with Pulse Shape Analyzer (PSA) is described. Three sets of pure alpha and pure beta standards simulating the activity concentration values of real samples in terms of α/β activity ratios were used to calibrate the LSC. Calibration methodology for the Quantulus 1220 with respect to the above measurements using 241Am and 90Sr/90Y standards of respective activity concentrations of ~25 dpm and ~104 dpm is described in detail. Also highlighted the need to calibrate the LSC using another set of 241Am and 90Sr/90Y standards of low and high activity concentrations respectively. The practicability and working performance of these calibration plots was checked by the validation trials with test samples spiked with 241Am and 90Sr/90Y covering range of α/β activity ratios from 1:1 to 1:50.

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