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- Author or Editor: R. Delmas x
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Abstract
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.
Abstract
A simplified calculation model of the recoil and irradiation enhanced diffusion which occur in neutron activation analysis of metals is proposed. Under usual irradiation conditions, the recoil does not exceed 0.01 μm for n, γ reactions and 2 μm for other reactions; the diffusion does not exceed 1 μm. Examples, in which deep impurity diffusion leading to important analytical errors was put forward, are discussed through this calculation model. In most cases, the observed phenomena are not related to diffusion but to other causes such as unefficient etching of the sample surface.
Abstract
A set of interactive routines has been developed to use a personal computer for instrumental neutron activation analysis. The program operates a multichannel analyzer by remote control and output concentrations, standard deviation and/or detection limit for each requested element. The program is able to combine data from several spectra, so that computation is continuous and takes less than 4 minutes for 15 elements. Reliable results have been obtained for low peak/background ratios encountered in atmospheric and marine particulate matter analyses.
Abstract
Thek
o-standardization method has been extensively used in the Pierre Süe laboratory during the last few years. We had developed two different new programs which both used parts of a commercial package (Canberra or Nuclear Data), for example: isotope parameter editor, automatic peak search, nuclide identification. However, further adaptation of these packages is not easy, due to the specific data handling of the two programs. In order to overcome these constraints, we decided to write a completely new program, Ko-LABSUE, which is as independent of the manufacturer specifications as possible. All of the different steps of thek
o-quantification (automatic peak search, nuclide identification, calculation of elemental concentration etc.) are processed by modules written in TURBO-PASCAL. Only two 
unit
modules have to be re-written to process manufacturer data files of different formats: the modules used to read the spectrum data and the detector efficiency curve. This program runs on an IBM-PC and is currently on
-test in our laboratory.
Abstract
The determination of Ir and Pt in rhodium neutron monitors was investigated via192Ir and199Au after neutron activation, via191Pt and194Au–196Au after proton activation. Ir was determined by instrumental NAA. A chemical separation of gold, with a yield measurement method by a radioactive tracer, was developed for platinum determination after neutron or proton irradiation.
Abstract
Instrumental neutron activation analysis (INAA), inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were used for the determination of major and trace elements in sediment samples of the Bouregreg river (Morocco). The reliability of the results was checked, by using IAEA Soil-7 certified reference material. Results obtained by the three techniques were compared to control digestions efficiencies. A general good agreement was found between INAA and both ICP-MS and ICP-AES after alkaline fusion (ICPf). The ICP-MS technique used after acid attack (ICPa) was satisfactory for a few elements. A principal component analysis (PCA) has been used for analyzing the variability of concentrations, and defining the most influential sites with respect to the general variation trends. Three groups of elements could be distinguished. For these groups a normalization of concentrations to the central element concentration (that means Mn, Si or Al) is proposed.
Abstract
The heavy metals bio-accumulation ability of algae was studied along the North Atlantic Morrocan coast. Instrumental neutron activation analysis was used, to determine concentrations of various elements. The k 0 standardization method was used. Some interferences corrections, particularly due to high concentrations of uranium were applied. The quality of the method was checked by using the CRM 140, a Fucus provided by IAEA. Important pollutions appear for several heavy metals from the Morrocan phosphate industry, with respect to the natural background environment.
