Analysis of radioactive cesium-enriched particles and measurement of their distribution in marine sediment near Fukushima Daiichi nuclear power plant
| Autor: | Tamaki Ura, Seiki Ohnishi, Naoteru Odano, So Kamada, Blair Thornton, Toshikazu Koike, Kazunori Nagano, Mitsufumi Asami |
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| Rok vydání: | 2021 |
| Předmět: |
Nuclear and High Energy Physics
010308 nuclear & particles physics 0211 other engineering and technologies Sediment chemistry.chemical_element 02 engineering and technology 01 natural sciences law.invention Oceanography Fukushima daiichi Nuclear Energy and Engineering chemistry law Caesium 0103 physical sciences Nuclear power plant Environmental science Submarine pipeline 021108 energy |
| Zdroj: | Journal of Nuclear Science and Technology. 58:482-492 |
| ISSN: | 1881-1248 0022-3131 |
| Popis: | Cesium-enriched particles released from the Fukushima Daiich Nuclear Power Plant (NPP1) exist in the Fukushima coastal waters and offshore, and they possibly affect the wide-area distribution of the radioactive cesium measured by the towed spectrometer. Therefore, the distribution of them in marine sediment was measured near NPP1 in November, 2016. We scanned the seafloor using a remotely operated vehicle (ROV) equipped with a NaI(Tl) scintillation detector. The sediment samples were obtained on the survey line by the ROV’s suction-type sampler. Five cesium particles, with diameters of approximately 400 μm, were isolated from the samples. The radioactivity of 137Cs was less than 360 Bq, and no nuclides other than 134Cs, 137Cs, and natural radioactive ones were found from gamma-ray spectroscopy. In the particles, titanium and calcium were commonly detected by energy-dispersive X-ray spectrometry. We also estimated the particles’ presence from the change in the total counting rate of the scintillation detector. The average particle density is found to be 3.45×10−2 m −1 at most. The average increase in the counting rate directly above the cesium-enriched particles in the sediment was less than double. Therefore, the effect of such particles on the distribution of radioactive cesium is limited. |
| Databáze: | OpenAIRE |
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