Optimization of 210Pb gamma-ray spectrometry determination in NORM samples

Abstract

This study investigates the optimization of ²¹⁰Pb determination in NORM samples using gamma-ray spectrometry in routine laboratory settings. It evaluates three methods of assessment: (A) sample in a ‘volume geometry’ with composition-estimated correction factor calculation, (B) thin layer measurement with composition-estimated correction calculation, and (C), thin layer measurement with experimental correction factor determination. The latter involves a direct measurement of the material-specific attenuation coefficient via a collimated photon beam, followed by a simplified Monte Carlo calculation of the self-absorption correction factor. A total of 107 samples representing a broad spectrum of NORM materials such as coal ash, sludge, cement byproducts, and zircon sands, were analyzed. The results reveal that ‘volume geometries’ are inadequate for ²¹⁰Pb determination, primarily due to excessive photon attenuation, even when the sample composition is known. Thin layer geometry with composition-estimated correction factors markedly improved accuracy, making this approach suitable for materials covering coal combustion products (ash and slag), byproducts of cement, old building materials, rocks, soil and furnace linings. However, experimental approach was the only reliable method for samples with high densities, complex compositions, or elevated attenuation coefficients—such as zircon sands. These findings contribute to the optimal use of resources and time.

Graphical abstract