Analysis of naturally occurring radioactive material using neutron activation analysis and passive Compton suppression gamma-ray spectrometry

摘要

Naturally occurring radioactive material (NORM) still remains a problem in oil and gas exploration. Radioactive wastes from oil and gas drilling take the form of produced water, drilling mud, sludge, slimes, or evaporation ponds and pits. In many parts of the USA the soil contains radioactivity that is then concentrated in mineral scales on the pipes, storage tanks and other extraction equipment. The radionuclides ~(226)Ra and its one of daughter products ~(210)Pb and ~(228)Ra from ~(232)Th are the primary radionuclides of concern in the waste. We have investigated the concentrations of heavy metals in NORM using neutron activation analysis (NAA) as well as using passive radioactivity counting using Compton suppressed gamma-ray spectrometry. With a low-energy germanium counter and the Compton suppression system low detection limits were achieved to measure ~(226)Ra, ~(228)Ra and ~(210)Pb. Results have shown very elevated amounts for these radionuclides as well as the heavy metals of barium and strontium.