Late Atmospheric Effects of a Nuclear Accident: Comparison Between the Fukushima Daiichi NPP and Chernobyl Accidents

Abstract

Nuclear disasters such as the Chernobyl nuclear power plant (NPP) and Fukushima Daiichi NPP (FDNPP) accidents have contaminated global atmosphere, terrestrial and marine environments by radioactive materials. The environmental impacts of the nuclear accidents continued over more than 10 years. In this chapter, we focus on long-term atmospheric effects of the nuclear accidents by comparing impacts of the FDNPP and Chernobyl for better understanding of their long-term atmospheric effects. For both accidents, the atmospheric concentrations of 137Cs, which is a major radionuclide released from damaged reactors, decreased rapidly with an apparent atmospheric half-life of 1 and 2 weeks at the initial stage, and after that decreased gradually with an apparent atmospheric half-life of about 1 year. The areas affected by the late atmospheric effects correspond to a slow decrease rate of airborne 137Cs, depending on the total release of radioactivity. The late atmospheric effects have been related to radionuclide resuspension and additional emissions from the damaged reactors. However, the current understanding of resupension is more complicated, as it depends on the wind blow of soil particles, human activity in fields as well as on roads and construction sites, forest fires, ecosystem activities of forests, and others. It is noteworthy that a significant fraction of radioactively contaminated areas for both major accidents was forested. These findings suggest that long-term atmospheric radioactivity monitoring is necessary to assess the environmental effects of the nuclear accidents.