Study of particular problems appearing in NORM samples and recommendations for best practice gamma-ray spectrometry

In this paper spectral interference effects for selected gamma-emitting radionuclides of the natural decay series and 40K in selected NORM samples are studied. Recommendations for the choice of γ-lines and the consideration of possible spectral interferences are provided. Special attention is given to the radon tightness of the sample containers. A simple and sensitive method for the estimation of the 222Rn leakage of sample containers is introduced. The applied polystyrene sample containers show 222Rn leakages lower than 1%.