A Comparison of Current Methods for the Determination of Ra-226 and Ra-228 in Water by a Modified Georgia Tech Gamma Method Vs. US Environmental Protection Agency Drinking Water Methodologies.

Abstract

Radium is a significant source of human radiation exposure both from natural sources (NORM, or Naturally Occurring Radioactive Material) and from technologically enhanced natural radioactive material (TENORM). Gamma analysis for 226Ra and 228Ra in water using high purity germanium (HPGe) detectors was compared with current methods from the US Environmental Protection Agency (EPA) using alpha scintillation and gas proportional counters. Extensive evaluations of a modified version of the original Georgia Tech HPGe method were performed. Known value 226Ra samples from the US Department of Energy (DOE) Mixed-Analyte Performance Evaluation Program (MAPEP) program, mixed 226Ra and 228Ra samples from the Environmental Resource Associates Quality Assurance Program (ERA), and mixed 226Ra and 228Ra samples from the Laboratory Proficiency Testing Program of the International Atomic Energy Agency (IAEA) were used for cross-check comparisons of the modified Georgia Tech method with other methodologies (EPA 903.1 and Ra-05 for 226Ra and 228Ra, respectively). Minimum counting times for our gamma instrumentation to reach a minimum detectable activity (MDA) of 0.04 Bq L-1 were also determined.