Sample treatment techniques for the determination of environmental radiocarbon in a nuclear power station area

This report describes the environmental sample treatment techniques for C-1 4 measurement with liquid scintillation counter. The groundwater sample of about 80 liters was collected from well and inorganic carbon was removed by acidification and recirculated gas stripping with the extraction efficienc y of more than 98%. The biological samples were freeze-dried and combusted to carbon dioxide in high pressure combustion unit with a combustion effici ency of nearly 99%. The (CO2)-C-14 in the stack effluents was collected by an air bubbler with a collection efficiency of more than 99% for a sampling rime of two weeks. Sampling of C-14 in reduced form also has been done by passing the gases through a tube furnace with Pt/Al and Pd/Al catalyst. Act ive and passive sampling methods for atmospheric C-14 measurements were com pared in detail, and it could be concluded that the uncertainty associated with passive sampling method was quite acceptable for environmental monitor ing. The CO2 trapped in NaOH was precipitated as BaCO3, and subsequently re converted to CO2 for environmental samples and transferred to Carbo-Sorb E( TM) for liquid scintillation counting. In case higher precision is the deci ding factor, benzene synthesis would be employed with home-made benzene syn thesizer.