Bentonite Characterization by Nuclear Techniques for Environment Applications

Three bentonites samples from the M'Zila deposit, W. Mostaganem, Algeria, were characterized by the Instrumental Neutron Activation Analysis (INAA) and the X-ray fluorescence analysis (EDXRF) techniques which are two very sensitive, multi-elementary and precise nuclear analysis techniques, in particular the INAA technique which is well suited for the characterization of bentonites with a low detection limit. The characterization of these samples consists in determining their chemical compositions in major, minor and trace elements, in particular their rare earth element compositions (REEs), which are indicators of the presence of fissile elements such as uranium and thorium in order to valorize these materials subsequently to the treatment of radioactive waste. The samples were irradiated at the nuclear reactor under a neutron flux of 2.36 × 1013 cm-2s-1 for 4 hours and measured by gamma spectrometry, using a high resolution HPGe semiconductor detector (1.8 keV for the line 1332.5 keV of 60 Co).The spectra were analyzed using the gamma vision software dedicated to the treatment of gamma spectra. For a second analysis companion, the samples were excited with an X-ray beam of a current 20 μA, generated by a generator of RX with a voltage of 30KV and equipped with a silver anode. The spectra of the bentonite samples were obtained using a SDD type detector with a thickness of 7.62 μm and an active surface area of 25 mm 2, and its resolution is 135 eV for the line 5.9 keV of 55 Fe. The determination of the concentrations of trace elements and rare earths completed with very satisfactory and accurate results, allowed us to see the effect of the chemical changes made on our raw sample that will serve us for a reliable and logical interpretation of the results from the valorization of these materials to the treatment of radioactive waste.