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Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*
Journal of Radiological Protection, 42(4), p.041503_1 - 041503_12, 2022/12
Times Cited Count：1 Percentile：29.26(Environmental Sciences)Sheltering is one of the countermeasures against radiation exposure during nuclear accidents. The effectiveness of sheltering for inhalation exposure is often expressed by the reduction factor, which is defined as the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. Meanwhile, the air exchange rate depends on surrounding environmental conditions: the wind speed, leakage area normalized by the floor area of the house, and gross building coverage ratio. In this study, the ranges of the uncertainty of the reduction factors for particles and I
were investigated under various environmental conditions, and sensitivity analyses were conducted to understand the parameter with the most influence on the uncertainty of the reduction factor. From the results of the uncertainty analyses, the calculated reduction factor was highly variable depending on the environmental condition and the airtightness of the houses. The uncertainty ranges of the reduction factor for particles and I were up to 0.9 and 0.3, respectively, and were smaller for newer houses. From the results of the sensitivity analyses, the wind speed was the most influential parameter on the reduction factor. Additionally, the wind speed was less influential for the reduction factor in newer houses.
Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*
Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09
Times Cited Count：23 Percentile：75.48(Environmental Sciences)UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.
Okoshi, Minoru; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki; Takahashi, Tomoyuki; Kimura, Hideo
Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 8 Pages, 1999/09
no abstracts in English
Endo, Akira; Takada, Hiroshi; Yamaguchi, Yasuhiro
JAERI-Data/Code 97-039, 37 Pages, 1997/10
JAERI-Data-Code-97-039.pdf:1.36MB
no abstracts in English
Takada, Kazuo
Shinkokyu Kido Moderu; Gaiyo To Kaisetsu, 0, p.11 - 15, 1995/03
no abstracts in English
Yabe, Akira
KURRI-TR-235, p.63 - 71, 1982/00
no abstracts in English
Takada, Kazuo
Hoken Butsuri, 12(1), p.19 - 24, 1977/01
no abstracts in English
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*; Watanabe, Masatoshi*; Munakata, Masahiro
no journal, ,
no abstracts in English
Manabe, Kentaro; Takahashi, Fumiaki
no journal, ,
A dose estimation system which integrates external and internal exposure is being developed to contribute to radiation protection for members of the public from radionuclides released into the environment. For internal exposure, inhalation of radioactive aerosols should be considered, and internal doses by inhalation depend on their diameters, densities, shape. However, dose coefficients published by the International Commission on Radiological Protection (ICRP) are developed with the assumption that distribution of particle diameters has a specific log-normal distribution. In addition, the existing codes can consider only a single value or a log-normal distribution for diameters of particles and do not fit the divisions of particle deposition determined by the revised Human Respiratory Tract Model (revised HRTM). Therefore, we developed a function of the dose estimation system which can calculate deposition fractions of inhaled particles having a given diameter distribution, density, and shape factor using the deposition model of ICRP. This function reproduced the deposition fractions for adult males in a light exertion level. In future, this function will be put in the dose estimation system to calculate internal dose coefficients under various conditions.
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*; Munakata, Masahiro; Kimoto, Shigeru*; Yoneda, Minoru*; Matsui, Yasuto*
no journal, ,
no abstracts in English
Kimoto, Shigeru*; Sadatani, Yoshiro*; Yoneda, Minoru*; Matsui, Yasuto*; Hirouchi, Jun
no journal, ,
no abstracts in English
