Assay methods for U-238, Th-232, and Pb-210 in lead and calibration of Bi-210 bremsstrahlung emission from lead

摘要

Methods for measuring U-238, Th-232, and Pb-210 in refined lead are presented. The U-238 and Th-232 concentrations are determined using isotope dilution inductively coupled plasma mass spectrometry after anion exchange column separation of dissolved lead samples. The Pb-210 concentration is inferred through alpha-spectroscopy of a daughter isotope, Po-210, after precipitation separation of dissolved lead samples. Subsequent to the Po-210 alpha-spectroscopy measurement, a method for evaluating Pb-210 concentrations was developed via measurement of bremsstrahlung radiation from beta-decay of a daughter isotope, Bi-210, using a 14-crystal array of high purity germanium detectors. Ten sources of refined lead were assayed and results are presented.