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| Titel |
Activity ratios in soil contaminated by the source of different reactor condition in the FDNPP accident |
| VerfasserIn |
Yukihiko Satou, Keisuke Sueki, Kimikazu Sasa, Tetsuya Matsunaka, Nao Shibayama, Tsutomu Takahashi, Norikazu Kinoshita |
| 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 |
250094691
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| Publikation (Nr.) |
 EGU/EGU2014-10119.pdf |
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| Zusammenfassung |
| The Fukushima Dai-ichi Nuclear power plant (FDNPP) accident caused radioactive
contamination on the surface soil at Fukushima and its adjacent prefectures. Substantial
contamination has been found in the northwestern area from the FDNPP, according to the
airborne monitoring and ground base survey by the Japanese government. Activity ratios
would have characteristic information on emission sources because each relevant
reactor had different amount of radionuclide and different activity ratio. The ratios
can be used to clarify more detailed source and process in the contamination. We
have addressed to consider them in Namie town, northwestern region from the
FDNPP.
This study focused on the gamma-ray emitting radionuclides of 134Cs, 137Cs, and 110mAg.
The activities were decay-corrected as of 11th March, 2011 when all nuclear reactors
scrammed. Data of activity ratios by our results and the Japanese official report classified the
investigated northwestern region into 3 groups. Ratios of 0.02 for 110mAg/137Cs and 0.90 for
134Cs/137Cs were observed in the northern region of 15 km inside from the FDNPP. On the
other hand, two kinds of 110mAg/137Cs ratios of 0.005 and 0.002 were distributed
broadly in the region 60 km away from the plant. The 134Cs/137Cs ratio was 0.98
there.
The activity ratios of 110mAg/137Cs and 134Cs/137Cs in the northern region from the FDNPP
correspond to those of nuclear fuel in Unit 1 according to estimation using the ORIGEN
code. The 134Cs/137Cs in the northwestern area from FDNPP agrees with that of Unit 2 and
3. The 110mAg/137Cs ratios of 0.005 and0.002 are 1/5 - 1/10 of the Unit 2 and 3. Official
report has announced that discharges of the radionuclides from Unit 2 and 3 occurred on 14th
March, 2011. It is known that contamination in the northwestern region from the FDNPP
took place on 15th March, 2011. Plausible species for silver in reactor core, metal, and
halide etc. have higher boiling point than those species for cesium. The core would
be cooled down to lower temperature of the boiling point of silver at the timing
contamination occurred. Thus, silver with higher boiling point was not much released than
cesium with lower boiling point. The 110mAg/137Cs ratio has served to identify
the specific sources of contamination in the northwestern area from the FDNPP. |
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