دانلود رایگان مقاله ایزولاسیون ذرات رادیو اکتیو از زمین نزدیک نیروگاه هسته ای فوکوشیما

Abstract

The Fukushima Daiichi Nuclear Power Plant (F1NPP) accident in 2011 released radionuclides into the atmosphere in both aerosol and gaseous form. Subsequent studies of contamination in the environment have focused on the bulk radioactivity in samples. Comparatively little is known about the relative contribution and patterns of soluble versus particulate deposition of the radionuclides. We investigated a sample of heavily contaminated surface soil from a site 20 km northwest of the F1NPP and isolated four radioactive particles from the surrounding soil. These particles had a maximum particle area equivalent diameter of 6.4mm and a maximum 137Cs radioactivity of 67.5
0.1 Bq per particle. They were larger than the particles identified in aerosol samples shortly after the accident at a location 170 km southwest of the F1NPP. Two of the particles were spherical and two were fragmental. Silicates were a major component of the Fukushima radioactive particles. These characteristics clearly differ from the so-called hot particles observed at the Chernobyl accident in 1986. Clarifying the physical and chemical properties of the radionuclides released from the F1NPP accident is important for assessing the potential long-term impacts to humans.

5. Conclusions

The radioactive particles we collected from the polluted soil were larger and more active than Cs-bearing particles analysed by Adachi et al. (2013), Abe et al. (2014) and Yamaguchi et al. (2016), but their constituents were similar to, those of the reported aerosol particles. In addition, the present study demonstrated that silicates are one of the major components in the radioactive particle, and that the particle characteristics were different from those of so-called hot particles observed at the Chernobyl accident in 1986. We suggest that the present radioactive particles in the soil were discharged to the atmosphere during the same F1NPP emission event on 14 and 15 March 2011 with the source of previously reported Cs-bearing solid particles. Our results provide information on the temperature of materials ejected during the accident, some of which appear to have been molten. Our findings are useful to understand environmental dynamics studies of radioactive materials from the Fukushima accident. In addition, our findings have implications for the removal of the radioactive materials from the living areas and understanding of process of the accident. We suggest that additional investigations be conducted to analyse more particles from various distances from the F1NPP to elucidate the particle size–distance relationship, to determine the processes of synthesis of the particles in the reactor cores and peripherals, and to evaluate the effect of weathering on the particles in the environment.