Analysis of radioactive iodine

This report describes on the procedures of analysis of radioactive iodine. Among various nuclides of iodine, iodine-131 is most important from the viewpoint of exposure dose for the public. Therefore, this report is related to principally iodine-131. Measurement of activity is made by using a low background beta counting system, a NaI(Tl) scintillation counter, and a Ge(Li) detector. The detection levels by the present method are 0.5 pCi/m3 for air dust, 10 pCi/kg for vegetables, and 0.2 pCi/l to 30 pCi/l for milk. Air dust is collected on charcoal filter papers or charcoal cartridges. The measurement of activity is made by gamma-ray analysis. Chemical analysis and beta counting can be made. The iodine-131 is precipitation or sea water is measured by gamma-ray analysis. The gamma-ray analysis is also applied for the measurement of activity in vegetables. Three methods can be applied for the analysis of milk. Those are the direct gamma-ray measurement, the ion exchange and gamma counting, and the ion exchange and beta counting. The iodine-131 seaweeds is analyzed by using a NaI(Tl) scintillation counter or a Ge(Li) detector. (Kato, T.)