Multielement analysis of concrete from nuclear reactors by INAA,ICP-MS and ICP-AES

There is a need to know, before dismantling nuclear plants, how the induced radioactivity is distributed in concrete. Computer codes are used to predict such a distribution, by applying input data like, among others, the chemical composition of the material. Biological shield concretes with particularly high boron or barium concentrations had to be analyzed. Instrumental neutron activation analysis is not able to determine all elements, thus, additional techniques are required, like ICP-MS and ICP-AES. The respective performances of these techniques are discussed. For INAA, the thermal neutron self-shielding was empirically corrected by using comparisons between thermal neutron activation (TNAA), epithermal and fast neutron activation (ENAA), ICP-AES and ICP-MS measurements.     

Neutron activation analysis of the rare earth elements in rocks from the earth's upper mantle and deep crust

Three techniques for analyzing rare earth elements (REE) in geological materials are described, i.e. instrumental neutron activation analysis (INAA), neutron activation analysis with pre-irradiation chemical REE separation (PCS-NAA) and radiochemical neutron activation analysis (RNAA). The knowledge of REE concentrations in eclogites, peridotites and minerals from the earth's lower crust and upper mantle is very useful in constraining their petrogenetic history.     

Platinum determination by NAA in two road dust matrices

In this work, a method for platinum determination was studied. The method is based on neutron activation analysis coupled with a preirradiation concentration/separation procedure employing a Dowex ion exchange chromatographic column to overcome serious interferences from other elements.Two environmental matrices, Road Dust CW7 and Road Dust CW8, collected and prepared by the Bureau Communautaire de Reference as candidate reference materials, were analysed. Finally, only CW8 was certified as BCR 723. The results were compared with data obtained by other laboratories with various techniques.     

Determination of thallium in biological samples by thermal neutron activation analysis and low-level beta-counting

A procedure is described for the determination of thallium in complex biological matrices by thermal neutron activation analysis employing substoichiometric extraction of thallium(I) with 2-mercaptobenzothiazole (2-HMBT) at a pH of 7.5 into chloroform, and low-level beta-counting.     

Performance of NAA Methods in an International Interlaboratory Reference Material Characterization Campaign

An extensive database of analytical results from a recent biological matrix Reference Material Characterization Campaign permitted an intercomparison of the performances of various methods among each other and with "true" best estimate concentration values established for these materials. Six different variants of neutron activation analysis (NAA) methods were employed including: instrumental neutron activation analysis, instrumental neutron activation analysis with acid digestion, neutron activation analysis with radiochemical separation, neutron capture prompt gamma activation analysis, epithermal instrumental neutron activation analysis, and neutron activation analysis with preconcentration. The precision and accuracy performance of NAA-based analytical methods are compared with three other major techniques, atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) and mass spectrometry (MS) for 28 elements in 10 natural matrix materials.     

Determination of tungsten in ores by X-ray fluorescence technique and X-rays in neutron activation analysis

Two distinct analytical methods have been described for analysis of W in tungsten ores. For the proposed study, thick and thin samples were analyzed by using X-ray fluorescence technique with great accuracy. Standard comparison method is based on the measurement of K line for tungsten. Also, W has been determined in similar ore samples by neutron activation analysis followed by X-ray spectrometry employing a²³⁸Pu-Be neutron source. The measured Re K-X rays are emitted in internal conversion of¹³⁷W produced during thermal neutron activation.     

Practical applications of neutron activation and radioisotope techniques in optical waveguide research and development

Gamma-ray spectrometric survey analyses were used to screen raw materials available during the infancy of the optical waveguide research program. Examinations of γ-ray spectra and semiquantitative survey analyses showed most samples to be insufficiently pure for waveguide applications. Highly pure samples have been prepared successfully under carefully controlled conditions when the purification process is adequately monitored by analyses. Radioisotope techniques and neutron activation analyses were vital in the development of successful procedures for purifying various reagents from which glass could be subsequently fabricated by melting techniques. Contamination sources during fiber production have also been detected by neutron activation analyses.     

Separation and quantitative determination of Tl and Ba from environmental samples by thermal neutron activation analysis

Quantitative determination of thallium and barium in aquatic environmental samples employing radiochemical neutron activation analysis technique was carried out. Cerium(IV) molybdate was used as an inorganic ion-exchanger. The accuracy, precision and sensitivity of the method was determined. The determination factor of various elements was also evaluated.     

Non-destructive neutron activation analysis of the Naragh meteorite

The concentration of 18 elements in the Naragh meteorite that fell in Iran on August 18, 1974, has been measured by neutron activation analysis employing a high resolution Ge(Li) detector.     

Nutritional and Environmental Properties of Algal Products Used in Healthy Diet by INAA and ICP-AES

Spirulina platensis alga sampled in the Caribbean Sea and seven other commercial algal products available on the Italian market of different origin and aspect, have been analyzed by instrumental neutron activation analysis (INAA) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). By neutron irradiation and -ray spectrometry (INAA), as many as 20 elements could be measured instrumentally without any chemical treatment. Cu, Mg, Mn and Pb were determined after dissolution of the sample by ICP-AES. The cross-checking of the data, specifically by comparing those of Ca, Cr, Fe and Zn, obtained by the two techniques was found to be in good agreement. Special attention from analytical and nutritional point of view has been devoted to the toxic metals. The measurements have been carried out employing the reference algal material prepared by International Atomic Energy Agency (IAEA).     

Determination of molybdenum and cobalt in hydrodesulfurization catalysts using a computerized radioisotope x-ray fluorescence system

A rapid, non-destructive method is presented for the determination molybdenum and cobalt in hydrodesulfurization catalysts employing a PDP-11/05 computer-base radioisotope x-ray fluorescence technique. Precision for molybdenum and cobalt better than 2.5% and 4.0%, respectively, are achieved in 100 sec of fluorescent time. The values obtained by this method are in agreement with values from atomic absorption and neutron activation methods. Besides being nondestructive, only about 50 mg of sample is needed, and no time-consuming acid dissolution is required as in atomic absorption and colorimetric methods. The results for six different commercial catalysts are compared with determinations by atomic absorption, neutron activation analysis methods as well as an x-ray fluorescence system with manual calculations of the percentage of molybdenum and cobalt.     

Determination of total oxygen in standard rocks by cyclic activation analysis using a 14 MeV neutron generator

Total oxygen, in fourteen rock standards and three ores, was determined with an experimental set up employing cyclic activation analysis using a 14 MeV neutron generator gamma-spectroscopy and NaI(T1) detectors.     

Determination of cobalt by substoichiometric thermal neutron activation analysis

A selective method has been developed for the determination of traces of cobalt in different matrices by the sensitive technique of thermal neutron activation analysis employing radiochemical separation and substoichiometric extraction of Co/II/ with iso-nitrosobenzoylacetone into chloroform.     

Investigation of elemental distributions within a billlgical sample using neutron activation tomography

A preliminary result employing neutron activation tomography in the study of the diffusion of a preservative in a sample of Scots pine is presented. The ability to determine the spatial distribution of elements within the wood without recourse to destructive sectioning makes this a better technique than others currently available.     

Trace element analysis of biological materials by thermal and epithermal neutron activation analysis

A scheme for instrumental neutron activation analysis of biological materials is proposed. The scheme is based on a combination of thermal and epithermal activation. The accuracy is evaluated by analyzing 4 standard reference materials. Results from the analysis of human blood serum and plasma are given.     

Optimized automated activation analysis

A combination of special techniques has been developed for optimization of experimental conditions in order to improve the analytical capability, to facilitate automation and to broaden the applicability of instrumental neutron activation analysis. The techniques used are: (1) compensation for the rapid radioactive decay of short-lived nuclides with the increase of the counting efficiency by automatic source movement to the detector during the counting period, to minimize count rate variations and to prolong the counting period, (2) repeated cyclic and cumulative activation to improve the counting statistics, (3) instrumental correction of counting losses at high and varying count rates by a loss-free counting system and (4) differentiation of the reactor neutron spectrum to enhance the counts from the nuclides of interest by reducing matrix interferences. By optimized combination and automation of these techniques significant improvement of the capability of instrumental neutron activation analysis can be achieved.