UNDERSTANDING RADIOACTIVE 40-POTASSIUM AT THE JACKPILE MINE AND SURROUNDING AREAS WITH GAMMA SPECTROSCOPY

The Jackpile Uranium Mine in western New Mexico was once the world’s largest open-pit mine and today we aim to understand radionuclides in the surrounding area. The mine's proximity to the Rio Paguate (a primary water source for plant and animal life nearby) means radioactive mobility is probable. In collaboration with researchers at the University of New Mexico, our team at the University of Notre Dame collected sediment samples upstream, downstream, and at the mine site to investigate the natural abundance of radioactive elements by conducting gamma spectroscopy analysis. Sediments were collected from the surface and analyzed in the lab for 40–Potassium (40–K) levels using the 1460.8 keV spectral line, and sample homogeneity was confirmed using X-ray fluorescence. Using the gamma spectroscopy method, we found 40–K levels of 78.9 - 490.8 Bq/kg upstream, 23.5 - 600.2 Bq/kg at the mine site, including the Rio Paguate, and below detection limits - 318 Bq/kg in the downstream wetlands area. The X-ray fluorescence data confirmed that the tested samples were homogenous, and approximated a natural or near-natural K content for the region (with levels of 40–K ranging from 2.62 - 8.13% by weight). Our methods for the quantification of 40–K with gamma spectroscopy were confirmed against International Atomic Energy Agency (IAEA) reference materials IAEA-385 and IAEA-465. Using these findings, we provide a greater understanding of radioactive elements in the region and hone the gamma spectroscopy radionuclide detection method. The method used for 40–K can be applied to other radioactive isotopes that pose an environmental concern, and lays the groundwork for further method development.