Isotopic Compositions of 236U and Pu Isotopes in 鈥淏lack Substances鈥?Collected from Roadsides in Fukushima Prefecture: Fallout from the Fukushima Dai-ichi Nuclear Power Plant Accident

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• 作者：Aya Sakaguchi ; Peter Steier ; Yoshio Takahashi ; Masayoshi Yamamoto
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：April 1, 2014
• 年：2014
• 卷：48
• 期：7
• 页码：3691-3697
• 全文大小：312K
• 年卷期：v.48,no.7(April 1, 2014)
• ISSN：1520-5851

文摘

Black-colored road dusts were collected in high-radiation areas in Fukushima Prefecture. Measurement of ²³⁶U and Pu isotopes and ^134,137Cs in samples was performed to confirm whether refractory elements, such as U and Pu, from the fuel core were discharged and to ascertain the extent of fractionation between volatile and refractory elements. The concentrations of ^134,137Cs in all samples were exceptionally high, ranging from 0.43 to 17.7 MBq/kg, respectively. ^239+240Pu was detected at low levels, ranging from 0.15 to 1.14 Bq/kg, and with high ²³⁸Pu/^239+240Pu activity ratios of 1.64鈥?.64. ²³⁶U was successfully determined in the range of (0.28 to 6.74) 脳 10^鈥? Bq/kg. The observed activity ratios for ²³⁶U/^239+240Pu were in reasonable agreement with those calculated for the fuel core inventories, indicating that trace amounts of U from the fuel cores were released together with Pu isotopes but without large fractionation. The quantities of U and ^239+240Pu emitted to the atmosphere were estimated as 3.9 脳 10⁶ Bq (150 g) and 2.3 脳 10⁹ Bq (580 mg), respectively. With regard to U, this is the first report to give a quantitative estimation of the amount discharged. Appreciable fractionation between volatile and refractory radionuclides associated with the dispersal/deposition processes with distance from the Fukushima Dai-ichi Nuclear Power Plant was found.