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A separation method was investigated to perform off-line cadmium isotopic measurements on a (109)Ag transmutation target. Ion chromatography (IC) with Q ICPMS detection (quadrupole inductively coupled plasma mass spectrometry detection) was chosen to separate cadmium from the isobarically interfering elements, silver and palladium, present in the sample. The optimization of chromatographic conditions was particularly studied. Several anion and cation columns (Dionex AG11(®), CS10(®) and CS12(®)) were compared with different mobile phases (HNO(3), HCl). The separation procedure was achieved with a carboxylate-functionalized cation exchange CS12 column using 0.5 M HNO(3) as eluent. The developed technique yielded satisfactory results in terms of separation factors (greater than 5) and provides an efficient solution to obtain rapidly purified cadmium fractions (decontamination factors higher 100,000 for silver and palladium) which can directly be analyzed by multi collection inductively coupled plasma mass spectrometry (MC ICPMS). By applying the proposed procedure, accurate and precise cadmium isotope ratios were determined for the irradiated (109)Ag transmutation target., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A new method for the direct measurement of 237Np/238U ratio in irradiated UO2 pellets by multicollection inductively coupled plasma mass spectrometry (MC-ICP-MS) is proposed. It allows the determination of ratios down to 10 × 10–6 mol·mol−1 using ion counter and Faraday cup. This approach was validated by intercomparison with the usual two-step-method (Quadrupole ICP-MS for 237Np determination and isotope dilution mass spectrometry (IDMS) for 238U). For ratios between 10 × 10–6 and 100 × 10–6 mol·mol−1, expanded uncertainties (k = 2) varied from 2.75% to 0.81%, twice lower than the uncertainties determined by the usual method. [ABSTRACT FROM AUTHOR]

Abstract: In the nuclear domain, precise and accurate isotopic composition determination of elements in spent nuclear fuels is mandatory to validate neutron calculation codes and for nuclear waste disposal. The present study presents the results obtained on Cs isotope ratio by mass spectrometric measurements. Natural cesium is monoisotopic (133Cs) whereas cesium in spent fuels has 4 isotopes (133Cs, 134Cs, 135Cs, and 137Cs). As no standard reference material is available to evaluate the accuracy of Cs isotopic measurements, a comparison of cesium isotopic composition in spent nuclear fuels has been performed between Thermal Ionization Mass Spectrometry (TIMS) and a new method involving Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) measurements. For TIMS measurements, isotopic fractionation has been evaluated by studying the behavior of cesium isotope ratios (133Cs/137Cs and 135Cs/137Cs) during the analyses. For MC-ICPMS measurements, the mass bias effects have been corrected with an external mass bias correction using elements (Eu and Sb) close to cesium masses. The results obtained by the two techniques show good agreement: relative difference on 133Cs/137Cs and 135Cs/137Cs ratios for two nuclear samples, analyzed after chemical separation, ranges from 0.2% to 0.5% depending on the choice of reference value for mass bias correction by MC-ICPMS. Finally the quantification of the 135Cs/238U ratio by the isotope dilution technique is presented in the case of a MOx (mixed oxide) spent fuel sample. Evaluation of the global uncertainties shows that this ratio could be defined at an uncertainty of 0.5% (k =2). The intercomparison between two independent mass spectrometric techniques is fundamental for the evaluation of uncertainty when no isotopic standard is available. [Copyright &y& Elsevier]

A one step Cs, lanthanides (Ln), Pu and U separation using TRU resin (Eichrom), for subsequent isotopic analyses, is presented for samples of transmutation targets containing a predominant matrix of steel elements. Cs, Ln, Pu and U are successively eluted using minor volumes (<12 mL) of 2M HNO3, 4M HCl, 0.075M oxalic acid in 1M HCl media and 0.1M ammonium hydrogen oxalate in 0.02M HNO3 media, respectively. Accurate and precise isotopic compositions obtained for these elements by thermal ionization mass spectrometry or multiple collector inductively coupled mass spectrometry show neither significant fractionation nor contamination during the complete analytical process. [ABSTRACT FROM AUTHOR]

Abstract: The Th–U cycle was studied through the evolution of a 100μg 232Th sample irradiated in a moderated neutron flux of 8.01014 n/cm2/s, intensity close to that of a thermal molten salt reactor. After 43 days of irradiation and 6 months of cooling, a precise mass spectrometric analysis, using both TIMS and MC-ICP-MS techniques, was performed, according to a rigorous methodology. The measured thorium and uranium isotopic ratios in the final irradiated sample were then compared with integral simulations based on evaluated data; an overall good agreement was seen. Four important thermal neutron-capture cross-sections were also extracted from the measurements, 232Th (7.34±0.21b), 233Pa (38.34±1.78b), 234U (106.12±3.34b), and 235U (98.15±11.24b). Our 232Th and 235U results confirmed existing values whereas the cross-sections of 233Pa and 234U (both key parameters) have been redefined. [Copyright &y& Elsevier]

Abstract: The determination of 93Zr concentration, a long-lived radionuclide present in spent nuclear fuel and in the structural components of nuclear reactors, is a major issue for nuclear waste disposal purpose and to validate neutronic calculation codes. To measure 93Zr concentration in irradiated cladding material with a high precision, an analytical method based on the use of multiple collector-inductively coupled plasma mass spectrometer (MC-ICPMS) combined to isotope dilution technique was developed. First a radiochemical separation of zirconium from a zircaloy sample (a zirconium alloy used as a cladding material for nuclear fuel elements), has allowed to obtain a very pure zirconium fraction with no potential isobaric interferences for mass spectrometric measurements. Then as the determination of all zirconium isotope ratios in the sample is necessary for the isotope dilution method, a MC-ICPMS procedure was developed to perform these precise measurements. Finally, the determination of 93Zr concentration in the same sample was performed, after preparation and calibration of a 96Zr spike solution. The uncertainties obtained on isotope ratios of zirconium by MC-ICPMS were in the order of 0.1%. The final uncertainty obtained on the 93Zr concentration in the nuclear material used and after chemical purification was lower than 0.6%. [Copyright &y& Elsevier]

Abstract: Strontium-90 is one of the most important fission products generated in nuclear industry. In the research field concerning nuclear waste disposal in deep geological environment, it is necessary to quantify accurately and precisely its concentration (or the 90Sr/ 238U atomic ratio) in irradiated fuels. To obtain accurate analysis of radioactive 90Sr, mass spectrometry associated with isotope dilution is the most appropriated method. But, in nuclear fuel samples the interference with 90Zr must be previously eliminated. An inductively coupled plasma mass spectrometer with multiple collection, equipped with an hexapole collision cell, has been used to eliminate the 90Sr/ 90Zr interference by addition of oxygen in the collision cell as a reactant gas. Zr+ ions are converted into ZrO+, whereas Sr+ ions are not reactive. A mixed solution, prepared from a solution of enriched 84Sr and a solution of enriched 235U was then used to quantify the 90Sr/ 238U ratio in spent fuel sample solutions using the double isotope dilution method. This paper shows the results, the reproducibility and the uncertainties that can be obtained with this method to quantify the 90Sr/ 238U atomic ratio in an UOX (uranium oxide) and a MOX (mixed oxide) spent fuel samples using the collision cell of an inductively coupled plasma mass spectrometer with multiple collection to perform the 90Sr/ 90Zr separation. A comparison with the results obtained by inductively coupled plasma mass spectrometer with multiple collection after a chemical separation of strontium from zirconium using a Sr spec resin (Eichrom) has been performed. Finally, to validate the analytical procedure developed, measurements of the same samples have been performed by thermal ionization mass spectrometry, used as an independent technique, after chemical separation of Sr. [Copyright &y& Elsevier]

Abstract: Precise isotopic determination of gadolinium and samarium in spent nuclear fuels is necessary to validate neutronic calculation codes. This study presents an analytical strategy to correct mass bias phenomenon inherent to MC ICPMS for precise and accurate samarium and gadolinium isotope measurements. An external standard bracketing approach to correct for mass discrimination and an exponential law fractionation correction have been applied in this work. Due to the lack of isotopic reference materials for Gd and Sm, the reproducibility of all of the isotopic ratios has been evaluated on the basis of natural spex solution commonly used for ICPMS. These solutions have been analysed for comparison and discussion about their representative isotopic values by thermal ionization mass spectrometry. On the basis of TIMS and MC ICPMS investigations, it was observed that: (1) the choice in representative isotopic values of the elements are essential to obtain accurate isotopic results and (2) the dependence of the mass bias of gadolinium and samarium masses must be taken into account for precise and accurate isotopic results. A reproducibility better than 0.1% was obtained with extensive measurements of Gd and Sm solutions by MC ICPMS. When measured isotope intensities were high enough, standard deviation of Gd and Sm isotopic ratios for purified fractions of Gd and Sm fuel samples were better than 0.2%. From the results obtained in this study, the potential of MC ICPMS techniques for determination of precise and accurate Gd and Sm isotopic compositions was clearly demonstrated for nuclear applications. [Copyright &y& Elsevier]

Abstract: This study describes a new determination of the decay scheme and half-life of 93Zr. A pure 93Zr solution was obtained after chemical separation from the dissolution of an irradiated zircaloy sample. The concentration of 93Zr in the solution was measured by mass spectrometry, with an isotopic dilution technique. The activity of the solution was measured by liquid scintillation counting, using an efficiency tracing method. The measurement of the activity concentration of 93Nbm by X-ray spectrometry, allowed the determination of the 93Zr decay scheme and the calculation of the 93Zr detection efficiency. This leads to the calculation of the decay probability of 93Zr toward 93Nbm of (0.73±0.06) and to a half-life of 93Zr of (1.64±0.06)×106 years. These values are discussed in comparison with the evaluated values available in the literature. [Copyright &y& Elsevier]

Abstract: Thermal ionization mass spectrometry (TIMS) is a well established instrumental technique for providing accurate and precise isotope ratio measurements for elements with low first ionization potential. In the nuclear domain, particularly for the study of spent nuclear fuel sample solutions, the reduction of quantities is an important issue in order to decrease the analyst exposition to the radioactive samples. This paper presents experimental results obtained for picogram quantities of samples using electron multipliers (Channeltrons) implanted on the new generation of TIMS associated with the total evaporation (TE) acquisition method. TE method presents some advantages for the measurement of low quantities of samples in relation to the whole sample consumption and the integration of the whole signal. For this study, a Thermal Ionization Mass Spectrometer from IsotopX (Isoprobe-T) equipped with a multi-collector system including Faraday cups and four movable Channeltrons is used. This work is focused on lanthanide elements, and particularly europium, in relation to the importance of their characterization in the spent fuel to validate neutronic calculation codes. In a first approach, europium isotopic ratios by total evaporation method using Faraday cups are obtained for quantities down to 250pg. The results obtained by TE (Faraday cups only) on such low quantities confirm the potentialities of the method. A reproducibility of 2.5‰ (k =2), was obtained on the 153Eu/151Eu ratio (n =11), for natural samples with an accuracy around 1‰. In a second approach the same procedure is tested on Channeltron detectors by reducing the amounts of samples (from 50pg to 1pg). In order to obtain accurate isotope results, intrinsic parameters such as applied voltages, dead time and noise were determined. A Channeltron specific intercalibration gain method was also developed, as this parameter was found to be the major source of uncertainties using this type of detectors. The reproducibility on the 153Eu/151Eu ratio was respectively found around 3% (k =2). These results show the potentialities of isotopic measurements of sub-nanograms quantities and the different sources of uncertainties using total evaporation and Channeltrons on the Isoprobe-T. [Copyright &y& Elsevier]

Abstract: In the general frameworks of the nuclear fuel cycle and environmental research field, the Cs isotopic composition must be known with high precision and accuracy. The direct determination of Cs isotopes by mass spectrometry techniques is generally hampered by the presence of Ba isobaric interferences however. Here we present a new method which takes advantage of the collision-reaction cell based Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and allows to analyse Cs isotopes in the presence of Ba without prior separation step. The addition of N2O gas in the cell leads to an antagonistic behavior of Cs+ and Ba+ as the latter reacts with the gas to form BaO+ and BaOH+ products whereas Cs+ remains unreactive. The efficiency of the method was demonstrated for an UOx sample by comparing the results obtained (1) from the measurements of pure Cs fractions and (2) from Fission Products fractions containing more than 30 ionisable elements in addition to Cs, Ba, and where U and Pu were previously removed by using ion exchange resin. An excellent agreement is achieved between each set of experiments with an external reproducibility always better than 0.5% (RSD, k =2). This study confirms the strong potential of collision–reaction cell to measure Cs isotopes in presence of interfering Ba, precluding therefore former systematic chemical separations. [Copyright &y& Elsevier]