Matsuyama Tsugufumi, Izumoto Yukie, Ishii Kota, Sakai Yasuhiro, Yoshii Hiroshi
Department of Radiation Measurement and Dose Assessment, National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan.
Department of Physics, Faculty of Science, Toho University, Chiba, Japan.
Front Chem. 2019 Mar 22;7:152. doi: 10.3389/fchem.2019.00152. eCollection 2019.
As a country's law stipulates the effluent standard uranium concentration in drainage water, the uranium concentration must be determined when drainage water is released from a uranium handling facility, such as the Fukushima Daiichi nuclear power plant. The maximum allowable limit for uranium release at each facility is defined taking into consideration the situation of the facility, such as 1/10 to 1/100 of this effluent standard value. Currently, the uranium concentration of drainage water is commonly determined by α-particle spectrometry, in which several liters of drainage water must be evaporated, requiring about half of a day followed by 2-3 h of measurements, due to the low specific radioactivity of uranium. This work proposes a new methodology for the rapid and simple measurement of several levels of uranium in drainage water by a total reflection X-ray fluorescence (TXRF) analysis. Using a portable device for TXRF measurements was found to enable measurements with 1/10 the sensitivity of the effluent standard value by 10 times condensation of the uranium-containing sample solution; a benchtop device is useful to measure uranium concentrations <1/100 of the effluent standard value. Therefore, the selective usage of methods by a portable and benchtop devices allows for screening and precise evaluation of uranium concentrations in drainage water.
由于国家法律规定了排水中铀浓度的排放标准，所以在从铀处理设施（如福岛第一核电站）排放排水时，必须测定铀浓度。每个设施的铀排放最大允许限值是根据设施情况确定的，例如该排放标准值的1/10至1/100。目前，排水中的铀浓度通常通过α粒子光谱法测定，由于铀的比活度低，必须蒸发几升排水，这需要大约半天时间，随后进行2 - 3小时的测量。这项工作提出了一种通过全反射X射线荧光（TXRF）分析快速简单地测量排水中几个水平铀的新方法。发现使用便携式TXRF测量设备，通过将含铀样品溶液浓缩10倍，能够以排放标准值1/10的灵敏度进行测量；台式设备可用于测量低于排放标准值1/100的铀浓度。因此，通过便携式和台式设备选择性地使用方法，可以对排水中的铀浓度进行筛选和精确评估。
