The appropriate environmental sample to educate novice students in environmental radioactivity measurements using gamma ray spectroscopy

Abstract

Proper implementation of gamma ray spectroscopy for environmental radioactivity measurements can often be challenging when trying to achieve high accuracy and high precision results. Phenomena such as gamma-ray self-attenuation can potentially add to the overall uncertainty in measurements, especially for samples that are large (100–500 g) and contain high-Z materials in significant quantities. As well, most environmental measurements need extended periods of time for measurements typically between 12 and 36 h per sample, depending on sample size and radioactivity concentration levels. For more than one decade we have been involved in radioactivity measurements in the oil and gas exploration sector, primarily in analyzing scale, soil and sludges. Our experience has revealed that scale is an environmental sample that can easily be analyzed for ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in a relatively short period of time for only 20 g of material due to the unusually high concentrations of these radionuclides. All the daughter products that decay with gamma rays can also be readily measured. Because of the higher Z elements such as iron, barium and strontium in elevated concentrations, gamma ray self-attenuation is of paramount importance to elucidate, particularly for the 46.4 keV gamma ray belonging to ²¹⁰Pb. And finally, there is a clear major disequilibrium in the ²³⁸U and ²³²Th chains. All these radiological and chemical characteristics for oil scale make this an ideal candidate to quickly teach novice researchers about the challenges in natural occurring radioactive materials (NORM) in gamma ray spectroscopy measurements. In addition, the number of researchers involved in environmental radioactivity measurements is decreasing and the need for an education template such as the one presented in this work is a very good tool for novice researchers in NORM.