土壤中^90Sr测量的不确定度评估

为满足新实验室认证准则，准确报告测量结果的不确定度，本文对土壤中^90Sr测量的不确定度进行评估。通过分析测量结果不确定度来源，逐一对其不确定度分量进行量化，从而获得测量结果的合成相对不确定度和相对扩展不确定度。对于环境本底水平土壤样品合成相对不确定度和相对扩展不确定度分别为22％和44％（k=2）。结果表明，对测量结果不确定度的贡献大的因素依次是β放射性测量、仪器探测效率、样品钇化学回收率、样品质量、样品锶化学回收率，其相对不确定度分别是22％、4．4％、1．1％、0．83％、0．69％。

Evaluation of Uncertainty for Measurement Result of 90Sr in Environmental Soil Samples

In order to meet the requirement of roles newly issued for laboratory certification and report accurately the result of measurement, the uncertainty of measurement result of ^90Sr in environmental soil samples was evaluated. By analysis of the sources of uncertainty, important components were chosen and calculated to get combined uncertainty and relative expanded uncertainty. For the samples of soil background measurement, the relative combined standard uncertainty and the relative expanded uncertainty were 22% and 44% respectively. The results showed that the main factors affecting uncertainty were ranked as β radioactivity measurement, detector efficieney, chemical recovery of yttrium, sample mass and chemical recovery of strontium with uncertainties of 22% . 4. 4% . 1.1% . 0. 83% and 0. 69% resnectively.