摘要
为制备大流量气溶胶滤膜标准γ体源,采用参数优化的专用滴源装置,将放射性标准溶液60Co定量滴注在气溶胶取样滤膜上,晾干后对角折叠,并采用专用压样装置压制成与测量样品几何形状一致、密实的圆盘形固态物,密封保存。采用差重法对制备的滤膜标准γ源进行活度定值,制备的气溶胶滤膜标准γ体源活度值为4.4×10^(4 )Bq,相对扩展不确定度U(k=2)为3.6%。采用分割压制法对气溶胶滤膜标准γ体源进行均匀性测量,相对标准偏差低于5%。制备的滤膜标准γ源可为测量大流量气溶胶样品的γ谱仪效率刻度服务。
Determining the activity deposited in aerosol sampling filters in the context of monitoring the environment and their raleases remains a major metrological challenge because of the diversity of filters and their conditions for use.The lack of truly suitable standard filters precludes satisfactorily linking the radioactivity measurement of these filters to a primary reference.The majority of laboratories involved in this type of measurement use soild sources to calibrate their instruments.These sources are not representative of aerosol sampling on a filter.Indeed,the detection efficiency of the instrument is highly influenced by numerous parameters related to aerosol deposits in the filtering medium.To establish the aerosol filter standardγsource for radioactive aerosol monitoring during environmental radiation monitoring,the automatic sampler and pressure mould have been designed and prosessed.In order to make the radioactive material evenly distributed on the filter,the drop parameters which includes radioactive solution components,the drop source spacing and the drop source height have been optimizing,then the radioactive standard solution was quantitatively infused on the aerosol sampling membrance using a dotted drip method.After the filters are dried,the filtes are folded diagonally and pressed through the sample pressing mould,pressed into a compact disc-type which consistent with the geometric shape of the measured sample,sealed.The activity of prepared filter standard source was determined by the amount of radioactive solution added.The results show that the extended uncertainty of aerosol filter standardγsource activity is 3.6%(k=2).The uniformity of the aerosol filter source was measured by spliting and re-pressing.The results show that uniformity of the aerosol filter source is better than 5%.Aerosol filtration standardγsource for calibration of high flow aerosol sampleγspectrometer.This method of aerosol filter source preparation could also be used in the production of secondary standards,whose properties are more adapted to the needs of laboratories measuring radioactivity in filters than are the solid sources that they typically use.
作者
李明
徐利军
宋鑫鹏
肖振红
陈克胜
夏文
LI Ming;XU Lijun;SONG Xinpeng;XIAO Zhenhong;CHEN Kesheng;XIA Wen(National Key Laboratory for Metrology and Calibration Techniques, China Institute of Atomic Energy,Beijing 102413,China)
出处
《同位素》
CAS
2018年第6期370-374,共5页
Journal of Isotopes
