Delaminated method to determine the depth distribution of 152Eu in soil by in-situ HPGe γ spectrometry

The main limitation of in-situ γ spectrometry lies in determining the depth distribution of radionuclides. This paper describes a specific delaminated method to obtain depth distribution of 152Eu in soil. It is based on the notion that the relative γ-ray flux contribution from a certain soil layer varies with the depth distribution shape and a certain γ-ray energy. Through one measurement with standard in-situ HPGe γ spectrometry, the activity concentration of 152Eu in any layer at certain soil depth can be iteratively calculated. The unique advantage of the delaminated method for measurement of 152Eu is that neither the priori knowledge of depth distribution shape nor an unwieldy lead collimator is required. Experiments have been performed for feasibility validation at three locations in one radioactive contaminated site. After in-situ measurement at each location, 10 samples from different layers were collected for laboratorial analysis. Experimental results show that the depth distribution of 152Eu is close to Gaussian function shape, and the activity concentration results of the delaminated method are accordant well with the analysis of soil samples, with a maximum deviation of 18.1%.