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Shimada, Taro; Nemoto, Hiromi*; Takeda, Seiji
Hoken Butsuri (Internet), 57(1), p.5 - 29, 2022/03
Of the asbestos-containing wastes arising from the dismantling activities of nuclear facilities, those with radioactive concentrations that do not need to be treated as radioactive substances will be cleared from the nuclear regulatory control. Those will be disposed of or recycled as specially controlled industrial waste based on the Waste Management and Public Cleansing Act. The authors constructed evaluation scenarios according to the treatment manual for asbestos-containing waste and evaluated public exposure doses per year for 33 radionuclides. Based on the evaluated doses, the radioactive concentration corresponding to the dose criteria of 10 
Sv/y for clearance was calculated for each radionuclide and scenario. As a result, the evaluated concentration was equal to or higher than the current clearance level. It was confirmed that the application of the current clearance level for asbestos-containing wastes did not affect safety.
Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji
Mechanical Engineering Journal (Internet), 7(3), p.19-00569_1 - 19-00569_17, 2020/06
After treatments such as sieve classification and washing of decontamination soil taken in Fukushima prefecture, recycling of the treated soil in which radioactivity concentration level is relatively low to public engineering works is invented to reduce the amount of the decontamination soil that must be disposed of. In the present study, dose estimation for workers and the public was conducted from the viewpoint of application of recycling material of decontamination soil for land reclamation by considering exposure pathways from the construction to the servicing of the land as a greenery-covered area. In the case of revegetation with trees, uptake of Cs into trees was considered and the exposure from trees, trimmed or thinned trees, and organic deposit made from litter fall were evaluated. From the results, the concentration levels of radiocesium, 
Cs and 
Cs, for which the annual effective exposure dose does not exceed 1 mSv/y was calculated. In addition, the thickness of the cover soil required to maintain the exposure dose lower than 10 Sv/y for the public during servicing was ascertained. Furthermore, disasters were considered; for instance, by considering that tsunamis, fires, and concentrated heavy rain can increase exposure doses based on changes in the conditions of the reclamation land, we confirmed that the additional exposure dose during disaster and rehabilitation is lower than 1 mSv/y. Based on these evaluation results, we determined the concentration levels amenable to recycling.
Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05
no abstracts in English
Takeyasu, Masanori; Nakano, Masanao; Sumiya, Shuichi; Nemoto, Hiromi*; Kanno, Mitsuhiro*; Kurosawa, Naohiro*
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 4 Pages, 2010/05
The dose to the public at hypothetical accident of nuclear facility is estimated on the basis of the method described in the Japanese meteorological guideline. However, the radioactive decay during atmospheric dispersion of released radionuclide is not considered in the calculation formula in the guideline. Therefore, when the radionuclide of the half life such as a few min is released, the dose may be excessively over-estimated. In this study, the calculation code was developed which could consider the radioactive decay of the released radionuclide and the generation of the product. The dose calculated on the basis of the developed code was compared with that on the basis of the guideline.
Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji
no journal, ,
no abstracts in English
