Gamma-ray characterization of the uranium-series intermediate daughters from soil samples at the Peña Blanca natural analog, Chihuahua, Mexico
The Nopal I uranium deposit is located in the Sierra Peña Blanca, Mexico. The deposit was mined in the early 1980s, and ore was stockpiled close by. This stockpile area was cleared and is now referred to as the Prior High Grade Stockpile (PHGS). Some of the high-grade boulders from the site rolled downhill during stockpiling; for this study soil samples were collected from the alluvium surrounding and underlying one of these boulders. A bulk sample of the boulder was also collected. Because the Prior High Grade Stockpile had no ore prior to the 1980s, a maximum residence time for the boulder is about 25 years; this means that the soil was at background as well. The purpose of this study is to characterize the transport of uranium series radionuclides from ore to the soil. Transport is characterized by determining the relative activities of individual radionuclides and daughter to parent ratios. Isotopes of the uranium series decay chain detected include 210Pb, 234U, 230Th, 226Ra, 214Pb, and 214 Bi. Peak areas for each isotope are determined using gamma-ray spectroscopy with a Canberra Ge (Li) detector and GENIE 2000 software. The boulder sample is close to secular equilibrium when compared to the standard BL-5 (Beaver Lodge Uraninite from Canada). Results for the soils, however, indicate that some daughter/parent pairs are in secular disequilibrium. (Abstract shortened by UMI.)
French, Diana Caroline, "Gamma-ray characterization of the uranium-series intermediate daughters from soil samples at the Peña Blanca natural analog, Chihuahua, Mexico" (2006). ETD Collection for University of Texas, El Paso. AAI1434288.