Presentation Effects of marine pollution with radionuclides after the Fukushima Daiichi Nuclear Power Station accident

青野, 辰雄

An accident of the TEPCO’s Fukushima Daiichi Nuclear Power Station (FDNPS) has been passed about over four years since March 2011. Marine pollution had been caused by two major sources after the accidents. One is the release to the atmosphere to 23 March 2011. In the terrestrial environment, many kinds of radionuclides, such as iodine(I), caesium(Cs), tellurium, strontium, plutonium(Pu) and silver(Ag) were observed in the eastern Japan. The other is that the high-contaminated water in FDNPS had directly released to ocean in early April 2011. The pre-accident levels of 137Cs activities in seawater and sediments in the coastal areas around Japan were observed 1–2 mBq/L and 1 Bq/kg-dry, respectively. Direct release of the contaminated water to the ocean had caused the high levels of radiocaesium (134Cs+137Cs) and 131I in seawater, sediments and biota in the coastal area of Fukushima during the end of March to the early April. After the release of contaminated water had stopped, the Cs and I activities in seawater had exponentially decreased more than 10 times compared to the activities before the accident over time. However, the activities in sediment and marine biota have decreased more slowly than those in seawater and had large fluctuations. Fukushima-derived radionuclides were observed with the gamma-ray spectrometry, were 134Cs, 137Cs and 110mAg in sediments and marine biota around off Fukushima. 90Sr were not detected in the bony parts of fish and 239+240Pu activities in visceral parts were the same levels as before the accident. The dispersion of radionuclides released from the FDNPS in marine environment are summarized with the simulation models and the effects of activities and radiation for marine biota are also discussed with some assessment models.
ICRR2015 15th International Congress of Radiation Research

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