Development of ¹²⁹I AMS at the NSL: Environmental Sampling in the Great Lakes Region

¹²⁹I in the environment primarily comes from releases by European nuclear fuel reprocessing centers.  Iodine moves easily through the environment as it is highly soluble, volatile, and easily incorporated into biological organisms, which causes releases of ¹²⁹I in Europe to affect concentrations globally.  This high mobility makes ¹²⁹I an excellent environmental tracer in fields such as geology and nuclear safeguards.  However, because of its long half-life of 15.7 Myr, detection of ¹²⁹I through decay counting methods is often unrealistic because of the sample size required.  Accelerator mass spectrometry (AMS), on the other hand, is well suited for the detection of ¹²⁹I as it can identify individual ions through isotopic and isobaric discrimination which, for ¹²⁹I, relies on the time-of-flight method.  Environmental sampling throughout the United States has been mostly limited to areas surrounding nuclear facilities, which inspired the AMS group of the Nuclear Science Laboratory at the University of Notre Dame to measure ¹²⁹I concentrations in the Great Lakes region to establish a baseline for measuring the change of these concentrations in the future.  Preliminary results of ¹²⁹I measurements and future plans will be discussed.