Development and deployment of an underway radioactive cesium monitor off the Japanese coast near Fukushima Dai-ichi

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• 作者：J.A. Caffrey ; ^{caffreyj@onid.orst.edu} ; K.A. Higley ; A.T. Farsoni ; S. Smith ; S. Menn
• 关键词：Fukushima ; Dai-ichi ; Radiocesium ; Seawater ; Monitor ; Flow-through
• 刊名：Journal of Environmental Radioactivity
• 出版年：2012
• 期刊代码：45_0265931x
• 类别：env
• 出版时间：September, 2012
• 卷：111
• 期：Complete
• 页码：120-125
• 文件大小：982 K

摘要

A custom radiation monitoring system was developed by Oregon State University at the request of the Woods Hole Oceanographic Institute to measure radioactive cesium contaminants in the ocean waters near Fukushima Dai-ichi Nuclear Power Plant. The system was to be used on board the R/V Ka鈥檌mikai-O-Kanaloa during a 15聽d research cruise to provide real-time approximations of radionuclide concentration and alert researchers to the possible occurrence of highly elevated radionuclide concentrations. A NaI(Tl) scintillation detector was coupled to a custom-built compact digital spectroscopy system and suspended within a sealed tank of continuously flowing seawater. A series of counts were acquired within an energy region corresponding to the main photopeak of ¹³⁷Cs. The system was calibrated using known quantities of radioactive ¹³⁴Cs and ¹³⁷Cs in a ratio equating to that present at the reactors鈥?ocean outlet. The response between net count rate and concentration of ¹³⁷Cs was then used to generate temporal and geographic plots of ¹³⁷Cs concentration throughout the research cruise in Japanese coastal waters. The concentration of ¹³⁷Cs was low but detectable, reaching a peak of 3.8聽卤聽0.2聽Bq/L.