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A kind of amino-functionalized clay was prepared by grafting APTES from clay in the Alxa area (Inner Mongolia, China), and its application for the U(VI) removal from Alxa groundwater was studied in this work. The results indicate that the sorption strongly depended on the pH and ions. The presence of amino functional groups significantly enhances the adsorption of uranium on clay in groundwater. The sorption isotherms fitted well with the Langmuir model, whereas the sorption kinetics could be fitted by a pseudo-second-order model. These findings indicate that amino-functionalized clay can effectively adsorb U(VI) in complex groundwater samples.

NaI(Tl) detectors are frequently operated under unstable temperature conditions when used in an open environment. Temperature changes would result in a peak shift and spectral distortion during measurement. Two easy-to-implement methodologies are proposed to stabilize the measured spectrum without the necessity of adjusting the gain, which are a correction algorithm for temperature-caused peak-shift based on multiple characteristic peak area weighting factors and an interpolation correction algorithm based on multicharacteristic peak sequence. Both of them can be used when the relative channel displacement of characteristic peaks in the spectrum due to temperature changes is not constant. Experimental data obtained under controlled temperature conditions in the laboratory were adopted to correct a spectrum, with joint consideration of some known characteristic peaks, such as 40K, U (214Bi), or Th (208Tl) peaks. Through constructing a reversible temperature coefficient matrix, one can easily obtain the coefficients of the n-th polynomial describing the influence of temperature on peak position, which presents their nonlinear mathematical relationship. Then, corrections of these two effects can also be easily calculated. Comparing the experimental results, peak positions before and after correction, it is proved that the interpolation correction algorithm based on multicharacteristic peak sequence has better correction accuracy, but the temperature-caused peak shift correction algorithm based on the multicharacteristic peak area weighting factor has a shorter calibration time.

In radiometric measurements, the radiation characteristics of radon and its daughters will increase the detection background value and affect the detection results. Research institutes in various regions of the world have studied the effects of radon and its daughters, and have done a lot of work according to the special climate, geological conditions and characteristics of radioactive events in their regions. In the view of the influence of radon background in airborne gamma-ray spectrometry measurement, this paper summarizes the research results of radon background correction in gamma-ray spectrometry measurement from three aspects in the world scope: environmental radiation monitoring, radiation monitoring instruments and nuclear emergency monitoring. In the aspect of environmental radiation monitoring, the research unit mainly considers the climatic factors such as rainfall, temperature and humidity, atmospheric and hydrological changes and seasonal changes, geological factors such as altitude, mineral types, and measurement means such as alpha measurement and inverse derivation gamma measurement. In terms of radiation monitoring instruments, radon and its daughters are mainly considered to reduce the impact and improve the measurement accuracy. In the aspect of nuclear emergency monitoring, the main consideration is how to improve the accuracy of measurement and avoid false alarm. On this basis, the research trend and development direction of radon background correction in airborne gamma-ray spectrometry are put forward.

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