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| Titel |
Distribution of radionuclides in the surface sea water developed by aerial radiological survey |
| VerfasserIn |
Yayoi Inomata, Michio Aoyama, Katsumi Hirose, Yukihisa Sanada, Tatsuo Torii, Takaki Tsubono, Daisuke Tsumune, Masatoshi Yamada |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094968
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| Publikation (Nr.) |
 EGU/EGU2014-10404.pdf |
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| Zusammenfassung |
| This study provides new data analysis method of aerial radiological survey to monitor the
distribution of anthropogenic radioactivity in surface seawaters as a first attempt.
The aerial radiological survey was performed by the U.S. Department of Energy
National Nuclear Security Administration (DOE/NNSA) within a 30 km radius of the
Fukushima Daiichi Nuclear Power Plant (FNPP1) on 18 April 2011. We found good
correlations between the observed concentrations of FNPP1 derived radionuclides
(131I, 134Cs, 137Cs) in the surface seawater and gamma-ray dose rates by aerial
radiological surveys (correlation coefficients for 131I, 0.89; 134Cs, 0.96;137Cs, 0.95).
The detection limits of 131I, 134Cs, and 137Cs in surface seawaters for the aerial
radiological survey are 25, 21, 24 Bq L-1, respectively. Based on these relations, we
find that the area with high concentrations of the FNPP1 derived radionuclides
spread south-southeast from the FNPP1. The maximum concentrations of 131I,
134Cs, and 137Cs reached 303, 456, and 528 Bq L-1, respectively. The131I/134Cs
ratios in surface waters of the high activities area are about 0.6-0.7. Considering
the radioactive decay of 131I (half-life: 8.021 d), we confirm that radionuclides
in the surface seawater of this area are due to direct release from FNPP1 to the
ocean. From these results, it is concluded that the aerial radiological survey is very
effective to investigate the accurate distribution of anthropogenic radioactivity in the
surface seawater. Furthermore, the model reproduced the distribution pattern of the
FNPP1 derived radionuclides in surface seawater obtained by the aerial radiological
survey, although simulated results by regional ocean model are underestimated. |
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