Environmental radioactivity research on radio-iodine contamination by the Fukushima Daiichi Nuclear Power Plant accident

Abstract

The accident at the Fukushima Daiichi Nuclear Power Plant resulted in a substantial release of radionuclides including Iodine-131, Cesium-134, and Cesium-137 to the atmosphere, and caused significant contamination of the environment. Most parts of the eastern Japan were subjected to the radioactive contamination, especially in Fukushima Prefecture. An effective dose estimation of released ¹³¹I is important but difficult due to lack of data on the deposition of ¹³¹I. The long-lived radioiodine isotope ¹²⁹I (half-life: 1.57×10⁷ y) is one of the important radionuclides released from nuclear fuel reprocessing plants and nuclear accidents into the environment. This radionuclide has provided useful information on the behavior of radioiodines, whose half-lives are very short, in the environment. In particular, ¹²⁹I has been used as a tool to reconstruct the initial distribution of ¹³¹I (half-life: 8 days) at nuclear accidents. Therefore the determination of ¹²⁹I in soils in Fukushima is needed to reconstruct the distribution of ¹³¹I in the environment. In this article, I review recent studies on radioactive iodine in Fukushima.