Distribution of 129I in terrestrial environment released from the Fukushima No. 1 nuclear power plant accident and reconstruction of 131I precipitation by 129I

Abstract

Radioactive iodines are the most important radionuclides released from the Fukushima No. 1 nuclear power plant accident. However, it is difficult to measure ¹³¹I in terrestrial environment at present, because ¹³¹I has a short half life time of about 8 days. We have measured ¹²⁹I concentrations in the surface soil at the eastern area of the Fukushima Prefecture. ¹²⁹I/¹²⁷I ratios were measured by accelerator mass spectrometry (AMS) at the MALT, The University of Tokyo. After the accident, average isotopic ratio of ¹²⁹I/¹³¹I is estimated to 25.6 ± 5.8 on the 11th of March 2011. It is expected to estimate ¹³¹I precipitation from ¹²⁹I in the surface soil. In this presentation, we will report the distribution of ¹²⁹I in terrestrial environment and trial reconstruction of ¹³¹I precipitation by ¹²⁹I.