Analysis of ¹²⁹I in Radioactive Wastes by Accelerator Mass Spectrometry

Abstract

Accelerator mass spectrometry (AMS) was applied to measurement of ¹²⁹I/ ¹²⁷I ratio to determine ¹²⁹I concentration in radioactive waste. Solid phase extraction disks (Anion-SR) for chemical separation of iodine from radioactive waste samples were used to prepare AMS targets.This method made it possible to swiftly separate iodide ions from sample solutions, compared with a conventional liquid-liquid extraction method. Since the ¹²⁹I concentration is calculated from an ¹²⁹I/¹²⁷I ratio, the amount of an ¹²⁷I carrier added to a sample for chemical separation determines the measurable range of the ¹²⁹I concentration. Especially in a radiation controlled area, it is important to keep the background value of the ¹²⁹I/¹²⁷I ratio as low as possible. The present method was successfully applied to laboratory standards and liquid waste samples arising from nuclear facilities in Japan Atomic Energy Agency.