Scintillation gamma spectrometer for analysis of hydraulic fracturing waste products

Abstract

Flowback and produced wastewaters from unconventional hydraulic fracturing during oil and gas explorations typically brings to the surface Naturally Occurring Radioactive Materials (NORM), predominantly radioisotopes from the U238 and Th232 decay chains. Traditionally, radiological sampling are performed by sending collected small samples for laboratory tests either by radiochemical analysis or measurements by a high-resolution High-Purity Germanium (HPGe) gamma spectrometer. One of the main isotopes of concern is Ra226 which requires an extended 21-days quantification period to allow for full secular equilibrium to be established for the alpha counting of its progeny daughter Rn222. Field trials of a sodium iodide (NaI) scintillation detector offers a more economic solution for rapid screenings of radiological samples. To achieve the quantification accuracy, this gamma spectrometer must be efficiency calibrated with known standard sources prior to field deployments to analyze the radioactivity concentrations in hydraulic fracturing waste products.

Spectrum Quantification of Radium Isotopes in Hydraulic Fracturing Wastes

“…Once an energy peak is identified and associated with a known radioisotope, to quantify the radioactivity requires a further efficiency calibration of the system against standard sources of known activity concentration. This procedure is described in detail in reference [5].…”

“…The first commercially deployed mobile spectroscopic radiation inspection system with shielding for low-activity measurements of radium isotopes in hydraulic fracturing wastes was developed by Ying [4], and hereby referred to as a TENORM Analyzer. The instrument was subsequently used to test a variety of material contents including rock, soil and water samples extracted from the Marcellus shale basin [5].…”

Downblending Contaminated Radioactive Wastes

“…For identifying specific radionuclides in hydraulic fracturing TENORM wastes, it is the matching gamma energies that are used in the analysis. With appropriate energy and efficiency calibrations of the detector system, and volumetric mass measurement of the tested samples, it is possible to quantify the precise activity concentration of the sampled radioactive waste [11]. …”