Use of Cuprous Iodide as a Precipitation Matrix in the Radiochemical Determination of lodine-131 in Milk

Abstract

As a result of the implementation of the as low as reasonably achievable (ALARA) philosophy to the nuclear power industry, recent U.S. Nuclear Regulatory Commission (NRC) requirements have prompted high-sensitivity radiochemical analysis for the measurement of iodine-131 (I-131) in milk. The most recognized and commonly employed technique incorporates costly palladium iodide as the final precipitate in the radiochemical purification of the iodine chemical species. The procedure presented in this paper outlines the many advantages of using cuprous iodide (CuI) as the final precipitate. These include lower cost per analysis, consistent recoveries, better precipitate matrix, and good self-absorption characteristics. Typical lower-limit-of-detection values and operating characteristics obtained for high-sensitivity beta-gamma (β-γ) analyis are presented as well as gas proportional counting and a comparison of radiochemical and germanium (lithium) spectrometric results for environmental samples collected during the recent Chinese weapons fallout incident.