采用钙镁共沉淀和二氧化锰沉淀浓集进行大体积水中Pu的分析

采用沉淀浓集-离子交换方法对大体积水中Pu分析方法进行了实验研究。浓集过程采用了MnO₂沉淀、Ca-Mg共沉淀两种方案,水样体积为25 L时,两种沉淀法对钚分析的全程放化回收率均可达到70%左右,MnO₂沉淀法对于50 L以上水样回收率下降。Ca-Mg共沉淀法对100 L水样的全程放化回收率为63.5%~80.2%,平均值为(74.6±5.9)%(n=7),对^239+240Pu的最小可探测限为3.1 μBq/L(体积V=100 L,回收率Y=74.6%,测量时间t=72 h)。某实际淡水样品中^239+240Pu含量为9.32~15.6 μBq/L,取样体积为100 L时没有出现低于探测限的结果。

Analysis of Pu in large volume water by Ca-Mg co-precipitation and MnO2 precipitation

The method for Pu analysis in large volume water was studied by using a precipitation concentration-ion exchange method. MnO₂ precipitation and Ca-Mg co-precipitation were used in the concentration process. When the volume of water sample was 25 L, the total radiochemical recovery rate of the two precipitation methods can reach about 70%. When the volume of water sample was greater than 50 L, the recovery rate of MnO₂ precipitation decreased significantly. The total radiochemical recovery rate of 100 L water sample by Ca-Mg co-precipitation is 63.5% to 80.2%, the average value is 74.6%±5.9% (n=7), and the minimum detectable limit of ^239+240Pu is 3.1 μBq/L (volume V=100 L, recovery rate Y=74.6%, measurement time t=72 h). The content of ^239+240Pu in an actual fresh water sample was 9.32-15.6 μBq/L, and there was no result which is below detection limit when the sample volume was 100 L.