Can scintillation detectors with low spectral resolution accurately determine radionuclides content of building materials?

The current paper makes an attempt to check whether the scintillation NaI(Tl) detectors, in spite of their poor energy resolution, can determine accurately the content of NORM in building materials. The activity concentrations of natural radionuclides were measured using two types of detectors: (a) NaI(Tl) spectrometer equipped with the special software based on the matrix method of least squares, and (b) high-purity germanium spectrometer. Synthetic compositions with activity concentrations varying in a wide range, from 1/5 to 5 times median activity concentrations of the natural radionuclides available in the earth crust and the samples of popular building materials, such as concrete, pumice and gypsum, were tested, while the density of the tested samples changed in a wide range (from 860 up to 2,410 kg/m3). The results obtained in the NaI(Tl) system were similar to those obtained with the HPGe spectrometer, mostly within the uncertainty range. This comparison shows that scintillation spectrometers equipped with a special software aimed to compensate for the lower spectral resolution of NaI(Tl) detectors can be successfully used for the radiation control of mass construction products.

► NORM activity concentrations in various materials were measured by NaI(Tl) and HPGe spectrometers.
► Synthetic compositions and building materials with different NORM concentration were studied.
► Densities of the tested samples varied in a wide range (from 860 up to 2,410 kg/m3).
► The results by the NaI(Tl) system were close to those obtained with the HPGe spectrometer.
► Special software compensates for lower spectral resolution of NaI(Tl) detectors.