Mass Spectrometric Determination of Zirconium from a Resin Bead

Abstract

A sensitive, isotope dilution technique has been developed for the analysis of sub-microgram amounts of zirconium. The analysis is based on the increased thermal ion emission for Zr adsorbed on a single anion resin bead. Zr is isolated from a solution containing the sample and a highly enriched ⁹⁴Zr (96%) spike. The determination is made possible by using a high-sensitivity pulse-counting 2-stage 30-cm radius mass spectrometer. The detection limit depends upon the amount of the isotope spike added and the desired precision. Fifty nanograms of zirconium (sample plus spike) produce sufficient ion signals for reliable isotopic analysis so that fission Zr can be measured with blank correction to a precision of 3%. By this method for fission Zr in spent reactor fuel particles, contamination from normal Zr and Mo can be corrected out by making isotopic measurements before and after spiking and scanning masses 90 and 95 during analysis. Since neither masses 90 nor 95 are stable fission products, their presence is due to sample contamination and can be used for correction based on their normal isotopic distributions. Zone-refined tantalum ribbon, essentially free of normal Zr and Mo was selected as the ionizing filament. This method can be adapted to a wide variety of samples.     

A Bulk Resin Bead Procedure To Obtain Uranium And Plutonium From Radioactive Solutions For Mass Spectrometric Analysis

Abstract

A method is described for extracting representative uranium and plutonium samples from highly radioactive solutions for isotopic mass spectrometric analysis. Anion resin beads in the nitrate form are used to effect separation from fission products and other actinides. Conditions required to achieve separation are proper adjustment of the uranium and nitric acid concentrations. Once uranium and plutonium are adsorbed, each bead serves as a sample for mass spectrometric analysis, with plutonium and uranium being run sequentially from the same bead. Quantitative determination of the two elements is effected through the technique of isotopic dilution.     

The determination of plutonium by mass spectrometry using a [242]-plutonium tracer

An isotopic dilution method is described for the determination ot plutonium in samples of irradiated uranium using a ²⁴²Pu tracer. An aliquot of tracer is added to the sample and the mixture treated to ensure isotopic exchange; plutonium is then separated by an ion exchange procedure and an isotopic analysis made using an M.S.5. mass spectrometer. The precision (3 σ) for an aliquot containing 0.1 μg plutonium is 0.6%. A possible application of the method would be its use for control analyses of the feed solution in a chemical plant processing natural uranium fuel elements as, for example, the Windscale primary separation plant.     

In search of higher sensitivity: Pu isotopic analysis

Summary Thermal ionization mass spectrometry (TIMS) is an effective method for isotopic and ultra-sensitivity determination of plutonium. This project aims at improving the National Institute of Standards and Technology (NIST) TIMS system sensitivity for the analysis of plutonium from environmental samples. The TIMS detection limits for direct, electrodeposition, and resin bead source loading techniques were determined by systematically varying the amount of plutonium loaded on the rhenium filament. It has been shown in our preliminary work that the resin bead could produce a stable TIMS ion beam for as long as 6 h period with ?10⁸ Pu atoms loaded onto a single resin bead.     

Determination of isotopic composition and concentration of uranium,plutonium and neodymium by mass-spectrometric isotope dilution in the irradiated fuel of the Czechoslovak atomic power station A-1

Determination of the isotopic composition and concentration of uranium, plutonium and neodymium by mass-spectrometric isotope dilution is described. Isotopes²³³U,²⁴²Pu and¹⁵⁰Nd were used as spikes. Isotopic composition was measured with a Varian-TH 5 mass spectrometer. Optimum amounts loaded onto the filament were 2–5 μg U, ∼0.1 μg Pu and <0.1 μg Nd. The accuracy and reproducibility of the isotopic ratio and concentration measurements were evaluated.     

Combined application of alpha-track and fission-track techniques for detection of plutonium particles in environmental samples prior to isotopic measurement using thermo-ionization mass spectrometry

The fission track technique is a sensitive detection method for particles which contain radio-nuclides like ²³⁵U or ²³⁹Pu. However, when the sample is a mixture of plutonium and uranium, discrimination between uranium particles and plutonium particles is difficult using this technique. In this study, we developed a method for detecting plutonium particles in a sample mixture of plutonium and uranium particles using alpha track and fission track techniques. The specific radioactivity (Bq/g) for alpha decay of plutonium is several orders of magnitude higher than that of uranium, indicating that the formation of the alpha track due to alpha decay of uranium can be disregarded under suitable conditions. While alpha tracks in addition to fission tracks were detected in a plutonium particle, only fission tracks were detected in a uranium particle, thereby making the alpha tracks an indicator for detecting particles containing plutonium. In addition, it was confirmed that there is a linear relationship between the numbers of alpha tracks produced by plutonium particles made of plutonium certified standard material and the ion intensities of the various plutonium isotopes measured by thermo-ionization mass spectrometry. Using this correlation, the accuracy in isotope ratios, signal intensity and measurement errors is presumable from the number of alpha tracks prior to the isotope ratio measurements by thermal ionization mass spectrometry. It is expected that this method will become an effective tool for plutonium particle analysis. The particles used in this study had sizes between 0.3 and 2.0 μm.     

Low-level determination of plutonium by gamma and L X-ray spectroscopy

We have developed an analytical method for detection of²³⁹Pu in aqueous samples at concentrations as low as 10^–10M. This nuclear counting technique utilizes the uranium L X-rays, which follow the alpha-decay of plutonium. Because L X-rays are specific for the element and not for the individual isotope, the isotopic composition of the plutonium sample must be known. The counting efficiency in the 11–23 keV range is determined from a plutonium standard, and the concentration of the sample is then calculated from the L X-ray count and the isotopic composition. The total L X-ray count is corrected for possible contributions from other radionuclides present as impurities by measuring the low-energy gamma-spectrum for each contaminant to establish specific photon/X-ray ratios. The ratios are important when²⁴¹Pu and²⁴²Pu are measured, because the respective decay chain members produce non-U L X-rays. This new method can replace the use of labor-intensive radiochemical separation techniques and elaborate activation methods for analysis of²³⁹Pu in aqueous samples. It is also applicable for assaying plutonium in liquid wastes that pose possible hazards to the environment.     

Precise isotope ratio measurements for uranium, thorium and plutonium by quadrupole-based inductively coupled plasma mass spectrometry

Precise long-term measurements of uranium and thorium isotope ratios was carried out in 1 μg/L solutions using a quadrupole inductively coupled plasma mass spectrometer (ICP-QMS). The isotopic ratios of uranium (²³⁵U/ ²³⁸U = 1, 0.02 and 0.00725) were determined using a cross-flow nebulizer (CFN, at solution uptake rate of 1 mL/min) and a low-flow microconcentric nebulizer (MCN, at solution uptake rate of 0.2 mL/min) over 20 h. For 1 μg/L uranium solution (²³⁵U/²³⁸U = 1) relative external standard deviations (RESDs) of 0.05% and 0.044% using CFN and MCN, respectively, can be achieved. Additional short term isotope ratio measurements using a direct injection high-efficiency nebulizer (DIHEN) of 1 μg/L uranium solution (²³⁵U/²³⁸U = 1) at a solution uptake rate of 0.1 mL/min yielded an RSD of 0.06–0.08%. The sensitivity of solution introduction by DIHEN for uranium, thorium and plutonium (145 MHz/ppm, 150 MHz/ppm and 177 MHz/ppm, respectively) increased significantly compared to CFN and MCN and the solution uptake rate can be reduced to 1 μL/ min in DIHEN-ICP-MS. Isotope ratio measurements at an ultralow concentration level (e.g. determination of ²⁴⁰Pu/ ²³⁹Pu isotope ratio in a 10 ng/L Pu waste solution) were carried out for the characterization of radioactive waste and environmental samples.     

Spectrophotometric determination of trace uranium in geological samples by flow injection analysis with on-line levextrel resin separation and preconcentration

A flow-injection system with on-line separation and preconcentration is described for the spectrophotometric determination of trace uranium in geological samples. Uranium is selctively adsorbed from 0.7 mol l^?1 nitric acid on a microcolumn (40 mm long, 4.4 mm i.d.) containing levextrel CL-5209 resin (120–200 mesh) and separated from the sample matrix and most of the co-existing ions; 10-fold concentration is obtained. Eluted uranium is determined spectrophotometrically with arsenazo-III. The detection limit is μg l^?1 uranium and calibration is linear up to 0.3 mg l^?1 uranium With dual columns operated alternately for adsorption and elution, 30 samples can be analyzed per hour. Masking agents are added to eliminate interferences from thorium and iron. The method is sensitive and highly selective, easy to operate and suitable for routine analysis of geological samples for uranium.     

Simultaneous analysis of uranium and plutonium using thermal ionization mass spectrometry

Simultaneous isotopic analysis of uranium and plutonium using thermal ionization mass spectrometer coupled to a multi-collector detection assembly with 9 Faraday cups has been reported earlier. Subsequently investigations have been carried out (1) to understand the applicability of correction methodologies available to account for the contribution of²³⁸Pu at²³⁸U and (2) to evaluate the effectiveness of these methodologies on the accuracy of²³⁵U/²³⁸U atom ratio being determined, particularly when samples containing different U/Pu atom ratios. Isotopic fractionation for both U and Pu in the simultaneous isotopic analysis has been compared with the results of the individual analysis of these elements. The different isotopic fractionation factors observed for U were attributed to different conditions of analysis. There was no significant difference in the isotopic fractionation patterns for Pu. The consideration to extend this method to actual samples from our observations on synthetic samples with diferent U/Pu atom ratios containing U and Pu isotopic reference standards is described.     

Precise isotope ratio measurements for uranium, thorium and plutonium by quadrupole-based inductively coupled plasma mass spectrometry

Precise long-term measurements of uranium and thorium isotope ratios was carried out in 1 μg/L solutions using a quadrupole inductively coupled plasma mass spectrometer (ICP-QMS). The isotopic ratios of uranium (²³⁵U/ ²³⁸U = 1, 0.02 and 0.00725) were determined using a cross-flow nebulizer (CFN, at solution uptake rate of 1 mL/min) and a low-flow microconcentric nebulizer (MCN, at solution uptake rate of 0.2 mL/min) over 20 h. For 1 μg/L uranium solution (²³⁵U/²³⁸U = 1) relative external standard deviations (RESDs) of 0.05% and 0.044% using CFN and MCN, respectively, can be achieved. Additional short term isotope ratio measurements using a direct injection high-efficiency nebulizer (DIHEN) of 1 μg/L uranium solution (²³⁵U/²³⁸U = 1) at a solution uptake rate of 0.1 mL/min yielded an RSD of 0.06–0.08%. The sensitivity of solution introduction by DIHEN for uranium, thorium and plutonium (145 MHz/ppm, 150 MHz/ppm and 177 MHz/ppm, respectively) increased significantly compared to CFN and MCN and the solution uptake rate can be reduced to 1 μL/ min in DIHEN-ICP-MS. Isotope ratio measurements at an ultralow concentration level (e.g. determination of ²⁴⁰Pu/ ²³⁹Pu isotope ratio in a 10 ng/L Pu waste solution) were carried out for the characterization of radioactive waste and environmental samples. Received: 1 December 1998 / Revised: 25 January 1999 / Accepted: 31 January 1999     

A method for dating small amounts of uranium

In this study we describe a method for uranium dating (i.e. determination of the date of the last chemical purification undergone by the material) by measurement of the ²³⁰Th/²³⁴U ratio, applicable to sub-microgram quantities. The chosen protocol (AG1x8 resin in hydrochloric acid medium) has been tested on separation microcolumns (100 μl). This ‘microchemistry’ technique considerably limits the risks of contamination by reagents or the environment. Thorium extraction efficiencies were greater than 90 % and reproducible. The quantities of ²³⁰Th introduced by the chemical purification procedure were negligible. Using an ultra-sensitive inductively coupled plasma mass spectrometry measurement technique, detection limits of the order of femtograms (10^?15 g) of ²³⁰Th were obtained. The complete procedure, chemical separation and isotope measurement, was successfully tested and validated on a few micrograms of uranium.     

Determination of Uranium in Natural Waters by Solid Phase Spectrometry

Abstract

A microdetermination method (at the μg1^?1 level) for uranium has been developed, based on Solid-Phase Spectrophotometry (SPS). The uranium reacts with pyridylazo-resorcinol in the presence of fluoride to form a 1:1:1 red ternary complex, which is fixed on an anion-exchange resin. The resin absorbance is measured directly, and allows the determination of uranium in the range of 1–10μg1^?1, with an RSD of 4%. The method has been applied to the determination of U(VI) in natural waters from wells located near the deposits of industrial wastes from a uranium mineral plant in Andujar (Spain).     

Nuclear analytical application of thermionic mass spectrometry

Summary The relative uncertainty on the isotope abundance ratio measurements of uranium and plutonium samples by means of thermionic mass spectrometry at the Central Bureau for Nuclear Measurements (CBNM) in Geel, Belgium, has decreased to a level of about 2 · 10^–4.The improvement was mainly achieved through the preparation of synthetic isotope mixtures of uranium and plutonium, to a relative uncertainty of 0.01% (computed on a 2s basis) on the ratios of isotopes with major abundances. This allowed to determine some error sources more precisely, such as: — isotope fractionation, — non-linearity of the ion beam current measuring system.As a consequence CBNM is able to prepare certified uranium isotopic reference materials (U IRM's) for distribution, with a relative uncertainty of 0.07% (computed on a 2s basis) on the²³⁵U isotope abundance and to provide reference values on samples for the (European) Interlaboratory Measurement Evaluation Programmes (REIMEP).

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Nuklearanalytische Anwendung der Thermionen-Massenspektrometrie

     

Accurate measurement of uranium isotope ratios in soil samples using thermal ionization mass spectrometry equipped with a warp energy filter

A chemical and mass-spectrometric procedure for uranium isotopic analysis using a thermal ionisation mass spectrometer equipped with a Wide Aperture Retardation Potential energy filter has been developed and applied to uranium isotopic measurements for various soil samples. Soil samples were digested using a microwave digestor. Uranium was isolated from soil samples by the chemical separation procedure based on the use of anion-exchange resin and UTEVA extraction chromatography column. The isotope ratios were measured for two certified reference materials by using a VG Sector 54-30 thermal ionisation mass spectrometer in dynamic mode with Faraday cup and Daly ion counting system. Replicates of standard reference materials showed excellent analytical agreement with established values supporting the reliability and accuracy of the method. Precision of the ²³⁵U/²³⁸U ratio was achieved by a correction factor of 0.22% amu as a function of ion-beam intensity with sample loads of around 250?ng of U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations (SD). Uranium isotopic compositions have been determined in several reference soil samples such as Buffalo river sediment, NIST 2704, river sediment SRM 4350b and ocean sediment NIST-4357 and a Chernobyl soil sample. There was a significant deviation from the natural uranium in comparison with Chernobyl soil samples.     

An optical-fibre laser photometer for on-line measurements

An optical-fibre laser photometer is described for measuring on-line the concentration of the different oxidation states of uranium and plutonium. It is based on a dye laser with five exchangeable curvettes containing five different dyes. The dye laser is pumped by a nitrogen laser. To compensate for the influence of the concentration of nitrate on the absorbance of the different species, the conductivity of the solution is measured to give a correction factor. Fibre optics are used to connect the dye laser, the optical flow-through cell and the photometer. The deviation for the plutonium concentration for single-sample analysis is <1 g l^?1 for concentrations up to 50 g l^?1, and in the on-line mode is <0.14 g l^?1 for the same concentration range. For uranium, the deviation is <3.07 g l^?1 for a concentration range up to 77 g l^?1 in the on-line mode.     

Separation of plutonium from uranium using reactive chemistry in a bandpass reaction cell of an inductively coupled plasma mass spectrometer

Oxygen and ammonia were evaluated as reaction gases for the chemical separation between uranium and plutonium in the bandpass reaction cell or dynamic reaction cell (DRC) of the ELAN DRC II mass spectrometer. Both uranium and plutonium demonstrated similar reactivity with oxygen giving rise to corresponding oxides. At the same time, remarkable selectivity in the reaction with ammonia was observed. While uranium was rapidly converted into UNH ₂⁺ and UN₂H ₄⁺ , plutonium remained unreactive in the DRC pressurized with ammonia. This difference in the reactivity allowed the determination of plutonium isotopes in urine and water samples containing excess uranium without preceding separation procedure. Detection limits of 0.245, 0.092, 0.270 and 0.237 ng L^–1 were obtained for ²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu and ²⁴²Pu, respectively, in urine spiked with 10 g L^–1 of U.     

Assay of actinides in human urine by rapid method

A method using DGA resin (N,N,N′,N′-tetra-n-octyldiglycolamide on an inert support) was developed for the rapid analysis of actinides in urine samples. Samples acidified with HCl to 4 M were loaded directly (without digestion) onto a DGA column. Actinides were stripped simultaneously, α-sources were prepared by co-precipitation with NdF₃. Americium, plutonium and uranium were separated with acceptable high recoveries (40–80%). The americium, plutonium and uranium content of 100–200 ml urine samples was determined within 24 h with detection limits as low as 0.01 Bq l^?1. Based on model experiments using ¹⁴C-spiked urea, it was proven that high urea content can affect americium separation deleteriously due to irreversible fixing of americium on DGA resin.     

An inter-calibration campaign using various selected Pu spike isotopic reference materials

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).     

Detection of uranium in industrial and mines samples by microwave plasma torch mass spectrometry

Microwave plasma torch (MPT), traditionally used as the light source for atomic emission spectrophotometry, has been employed as the ambient ionization source for sensitive detection of uranium in various ground water samples with widely available ion trap mass spectrometer. In the full‐scan mass spectra obtained in the negative ion detection mode, uranium signal was featured by the uranyl nitrate complexes (e.g. [UO₂(NO₃)₃]^?), which yielded characteristic fragments in the tandem mass spectrometry experiments, allowing confident detection of trace uranium in water samples without sample pretreatment. Under the optimal experimental conditions, the calibration curves were linearly responded within the concentration levels ranged in 10–1000 µg·l^?1, with the limit of detection (LOD) of 31.03 ng·l^?1. The relative standard deviations (RSD) values were 2.1–5.8% for the given samples at 100 µg·l^?1. The newly established method has been applied to direct detection of uranium in practical mine water samples, providing reasonable recoveries 90.94–112.36% for all the samples tested. The analysis of a single sample was completed within 30 s, showing a promising potential of the method for sensitive detection of trace uranium with improved throughput. Copyright © 2016 John Wiley & Sons, Ltd.