以国家标准为基础,对环境水体中90Sr和137Cs的监测方法进行了技术改进:增大采样量(50～100 L),选择高效沉淀剂和低水平探测器.采用改进后的方法测定了50～100 L水中90Sr和137Cs,结果显示:90Sr和137Cs的浓集效率分别为(91.3±2.8)％和(97.2±1.4)％;90Sr的全程回收率为81.5％±2.8％;90Sr和137Cs的探测下限分别为8.6×10-4 Bq/L和9.8×10-4 Bq/L.50 L水中90Sr的比对结果显示,4家实验室测定值与标称值的相对偏差均小于11％.以上结果表明,该方法适用于环境水中微量90Sr和137Cs的监测,可满足环境本底调查和环境监测的要求.%Based on the national standard,the monitoring method of 90Sr and 137Cs in the environmental water was improved,such as increasing the sampling(50-100 L),selecting effective precipitant and low level detector.90Sr and 137Cs in the water(50-100 L) were measured using the improved method.Results show that the concentration efficiency of 90Sr and 137Csare (91.3+2.8)％ and (97.2+1.4)％.The full recovery of 90Sr are 81.5％±2.8％.The minimum detectable limit of 90Sr and 137Cs are 8.6 × 10-4 Bq/L and 9.8 × 10-4 Bq/L respectively.The comparison results about 90Sr in the water(50 L) show that the relative deviation of measured value of four units and the nominal value is less than 11％.The results show that this method is applicable to monitoring trace of the radioactive in the environment water and can meet the requirements of environmental background survey and environmental monitoring.
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