Study of the radioactive aerosol particle size distribution in the effluent air from NPP with the use of cascade impactor

Sorting of radioactive aerosol particles by aerodynamic diameter using a cascade impactor makes it possible to apply radionuclide specific methods to the analysis of radioactive particles collected on the collection substrate from individual stages. A method of calculating the activity median aerodynamic diameter (AMAD) is described, and the results from aerosol particle sampling in the ventilation stack of the Bohunice V-1 nuclear power plant during the years 1985-1990 are presented. Altogether 40 samples were collected during this time. Time intervals covering both normal operation of the two reactors and shut-downs for maintenance and refuelling of one reactor were used. The aerosol particle size distribution, AMAD and GSD (Geometric Standard Deviation) were calculated for 60Co and 137Cs when samples from individual periods were evaluated together. 60Co and 137Cs were chosen as representing respectively corrosion and fission products. Results from one sample are given for all 17 radionuclides found. The particle size distributions are presented in the form of histograms, AMAD and GSD are presented in tables. (author) 4 tabs., 4 figs., 2 refs