Development Technology for the Preparation of High-volume Aerosol Filter Standard Gamma Source

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 standard γ source 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 standard γ source 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 standard γ source for calibration of high flow aerosol sample γ spectrometer. 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.