Radium and Uranium Determination in Samples of Utah Roses Geothermal Water
Water samples from the Utah Roses geothermal well in Salt Lake City, Utah, were received with a request for radium and uranium analysis. Geothermal waters often contain natural occurring radioactive elements at levels too high to be released to the environment. Radium cannot be determined by measuring the radon daughters with gamma counting instruments because the radon, being a gas, can diffuse through the rocks and soil and can accumulate in underground waters. In some studies the radon has been a factor of 10 times hither than the radium in underground water. A chemical separation of the radium and uranium and a direct determination of each are necessary for reliable results.
The method of direct alpha counting on separated elements was used for the analysis of geothermal water. This has the advantage of being rapid and economical for low-level activity. There are other reliable procedures having higher accuracy than direct alpha counting. However, equipment for this was not available in our laboratory.
Sill and Williams and Sill and Willis have reported a method of separating radium, thorium, protactinium, uranium and the transuranic elements on barium sulfate. In geothermal waters where the only alpha-emitting activity is due to uranium and thorium and their daughters, the barium sulfate method id the procedure of choice. Since radium and thorium are determined together, the radium content may be less than the number reported, but cannot be higher.