Performance of Multiple HEPA Filters Against Plutonium Aerosols

Field sampling has provided C. Elder, and Manuel Gonzales general criteria defining plutonium aerosol size characteristics and activity concentrations from typical plutonium operations. Two fabrication facilities have aerosols with activity median aerodynamic diameter’s (amad) ranging from 2 to 5 pm; the two research and development facilities indicate amad’s ranging from 1 to 4 ~; and a recovery facility consistently shows a sub-micron aerosol with a typical amad of 0.3 pm. This recovery facility also produces aerosols as small as 0.1 pm amad, has the highest activity concentration, and constitutes the most difficult air cleaning problem. Using laboratory produced plutonium test aerosols with size characteristics similar to those defined by the field sampling program, multiple HEPA filter systems were evaluated to provide quantitative data defining performance of successive stages of HEPA filters, and filter performance as a function of particle size. Test data show that the first and second HEPA filter each provide overall efficiencies in excess of 99.99%, while the third HEPA filter provides an average efficiency in excess of 99.8%. These performance levels exceed AEC requirements. Data defining performance of the first and second HEPA filters as a function of plutonium aerosol size show that HEPA filter efficiencies are in excess of 99.99% for sub-micron plutonium aerosols. Theoretical calculations estimating alpha radiation dose to the filter fibers from particle! collected on the fibers indicate a dose on the order of 10 rads per minute. SUMMARY shows a sub-micron aerosol with a typical Field sampling and analysis of data amad of 0.3 pm. This recovery facility LASL, Rocky Flats, and Mound Laboratoalso produces aerosols as small as 0.1 w has been completed to provide general amad, has the highest activity concentration, criteria defining plutonium aerosol size characteristics and activity concentrations from typical plutonium operations. The two fabrication facilities have aerosols with activity median aerodynamic diameter’s (amad) ranging from 2 to 5 W; the two research and development facilities indicate amad’s ranging from 1 to 4 ~; and the single recovery facility consistently and constitutes the most difficult air cleaning problem. Various data handling techniques were developed to indicate the variations in aerosol size characteristics at each facility. These included definition of the weighted average aerosol size parameters, evaluation of daily variations in aerosol size characteristics, and estimation of