Measurements of 129I in a nuclear power reactor by accelerator mass spectrometry

Abstract

The method of accelerator mass spectrometry is applied to measurements of concentrations of the long-lived volatile fission product 129I ( t 1 2 = 1.6 × 10 7 a) in the primary heat transport (PHT) system and irradiated fuel bay (IFB) of a commercial nuclear power reactor. Concentrations of (8.1 ± 1.1) × 10 12 129I atoms per gram and between 10 11 and 10 13 129I atoms/L were measured in an ion-exchange resin and in the heavy water (PHT) system, respectively. The corresponding value for the IFB system water samples was 5–6 × 10 12 129I atoms/L. These measurements, based on very small size samples (of the order of 0.5 mL) emphasize the advantage of the present method where a simple chemical process for the iodine extraction enables a direct measurement of the 129I atom content of the samples. In view of the physical and chemical properties of iodine and their important implications in the environment, the method is likely to find even wider applications for the monitoring of 129I and the study of long-range nuclear waste storage.