X射线荧光法测定天然铀产品中铀含量的不确定度评定

Evaluation of measurement uncertainty of the uranium content in natural uranium products determined by X-ray fluorescence method

利用X射线荧光法测定天然铀产品中铀含量,对测定结果的不确定度进行评定。建立了数学模型,分析了不确定度来源,计算合成标准不确定度和扩展不确定度。结果表明,标准曲线拟合、测量重复性、天平称量和标准样品量值对测定结果影响较大,当样品中铀的质量分数为84.736%时,其扩展不确定度U=0.078%(k=2)。

The content of uranium in natural uranium products was determined by X-ray fluorescence method,and the uncertainty of the determination results was evaluated.The mathematical model was established,the sources of uncertainty were analyzed,and the combined standard uncertainty and expanded uncertainty were calculated.The results showed that the fitting of the standard curve,the repeatability of the measurement,the weighing of the balance and the value of the standard sample had great influence on the determination results.When uranium content in the sample was 84.736%,the expanded uncertainty was 0.078%(k=2).