Presentation Determination of Pu isotopic composition using SF-ICP-MS for radiation impact assessment of Fukushima nuclear accident released Pu in the marine environment

Zheng, Jian  ,  Aono, Tatsuo  ,  Tagami, Keiko  ,  Uchida, Shigeo  ,  Yamada, Masatoshi

As a result of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, massive radionuclides were released into the environment. Compared with the plentiful studies on the volatile radionuclides, 134Cs, 137Cs and 90Sr, studies on actinides are much less. As one of the most important actinides, Pu isotopes attracted great public attention because they present a high risk for internal radiation exposure via ingestion of contaminated agricultural crops and seafood. Besides the possible atmospheric deposition of Fukushima-derived Pu into the sea, after the accident, contaminated water was leaked or directly discharged into the offshore of the FDNPP site, which is another possible pathway for Pu to enter the marine environment. Currently, the total amount of these high radioactive liquid wastes still remains unknown, whether the entrance of Pu derived from the FDNPP accident has a remarkable influence on the background Pu distribution in the western North Pacific needs to be studied.To better understand the Pu contamination in the marine environment after the accident, we developed highly sensitive analytical methods for accurate determination of Pu isotopic composition (239Pu, 240Pu and 241Pu) in marine samples (sediment and seawater) using SF-ICP-MS. For the first time, we determined Pu isotopes in seawater and sediments collected in the near coastal area (mostly within the 30 km zone) off the FDNPP site for radiation impact assessment. The results suggested that there is no significant Pu contamination in seawater in the near coastal area off the FDNPP site from the accident two years after the accident.

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