X-RAY FLUORESCENCE TECHNIQUE TO MEASURE TH AND U CONCENTRATIONS

The identification and detection of rare earth elements with low concentrations, such as Th and U, are important in Earth sciences, e.g., chronology, paleoclimatology, archeology, hydrology, geochemistry and oceanography due to their application as a chronometer and tracers. In nuclear research, specifically in dosimetry area, the radionuclides in the uranium and thorium decay chains are major contributors to gamma-emitting natural radiation from primordial radionuclides [1]. Therefore, the development of non-destructive analytical techniques to be used in the identification and the concentration determination of these elements is extremely important. Generally, to determine low quantity of these elements: thorium and uranium, is necessary to use techniques that require sophisticated sample preparation (ICPMS - Inductively Coupled Plasma Mass Spectrometry), large quantities of samples (Gamma-ray Spectrometry), or even the use of a nuclear reactor (NAA - Neutron Activation Analysis). Recently, it has increased the demand for simple analysis methods, which identify and quantify these elements quickly in small amounts of sample, without prior preparation. This work shows the use of a portable X-ray fluorescence, a fairly simple equipment, to characterize samples containing Th and U in low concentrations. This study presents the results obtained in the analysis of waste material samples generated by the industries of phosphate fertilizers, which require a control of its natural radioactivity [1]. From the results obtained it is concluded that this non-destructive technique is able to determine the contents of these elements at concentrations of tens of ppm order, with rapid measures of about 300 seconds. The XRF spectrometry presented in Figure 1 shows
X-ray uranium characteristic peaks.