In situ gamma spectrometry using a portable HPGe detector. Radiological characterisation and environmental surveillance around an operating nuclear power plant. Possibilities and limits.

Abstract

The in situ technique for measuring radionuclides in the soil using a portable Ge detector is a highly versatile tool for both the radiological characterisation and for the monitoring of operating nuclear power plants. The main disadvantage of this technique is related to the lack of knowledge of the geometry of the source whose activity concentration is to be determined. However, its greatest advantage is the high spatial representability of the samples and the reduced time and resource consumption compared to gamma spectrometry laboratory measurements. In this study, the possibilities and limits offered by in situ gamma spectrometry with a high-resolution gamma portable detector in two common uses are shown. First, the radiological background characterisation and its relationship with the geology of an area of 2700 km2 are assessed. Second, its potential for monitoring man-made activity concentration in soils located around an operating nuclear power plant in Spain for surveillance purposes is evaluated. Finally, high-accuracy radiation maps were prepared from the measurements that were carried out. These radiation maps are essential tools to know the radioactive background of an area, especially useful to assess artificial radioactive deposits produced after a nuclear accident or incident.